Off grid – K7JLX's blog

Estimating power consumption for your equipment

Hello everyone! Today I wanted to post about a topic that is pretty important if you have an interest in off grid, grid down, or emergency communications: estimating power consumption for your equipment. This post is in part inspired by a topic I chose for the Portland Neighborhood Emergency Team chat net. Shortly after I chose this topic I got an e-mail from Kevin, N6KVN asking for some advice for setting up a portable field station, and so I figured I’d write a more detailed post about my methodology and way of thinking about operating a ham radio station when grid power isn’t available from a preparation or pre-planning standpoint.

My basic test setup consists of three components. I have a power source of some kind. This could be a battery or a wall-connected power supply. The next component is a power meter connected between the load(s) and the battery. This component actually does the work of measuring power consumption. The final component of the test setup are the loads you wish to test. It’s important to make sure all the components in the setup are rated for the amount of current you expect to draw during testing. You can usually find that in the specifications of each individual component. You add those up and make sure your meter is rated for that much current and that your power supply can supply all of the required current. All the wiring in between should also be properly rated for that amount of current.

Example lighting current draw test

In this example I demonstrate testing a lighting device that runs on 12V and explain my methodology for hooking everything up and how I use back-of-the-napkin math to estimate power usage and requirements. In the above photo we have all three of our components for this specific test – a power source which is a battery in this case, the Powerwerx inline DC power meter, and load which is an LED lamp whose power usage I want to characterize. The Powerwerx inline meter supports a lot of measurements but in this post I’m going to mostly focus on current drawn and Ah, or amps per hour.

I started by connecting the power source to the “source” side of the power meter and then connected the load I wanted to test to the “load” side of the power meter. The images above show the light on but I will usually measure power with all the loads turned off to see if they draw current in the “off” position. It’s pretty common for devices to take a small amount of power even while off. This is called a parasitic load. The specific LED lamps I wanted to test have three settings: off, low, and high. I tested off and my power meter registered no current consumption. That’s probably because these lights have a hard off switch.

Power consumption with the switch in the “low” position

As you can see here this light draws 0.09A in the “low” position. If we were to run this device for 1 hour it would take 0.09Ah (amps per hour). You might have also noticed that there’s a measurement reading 0.001Ah. For this specific meter that means we’ve used 0.001Ah since the meter was connected to a load. There will be more on this measurement later.

The LED lamp with the switch in the “high” position

With the LED lamp in the “high” position it’s drawing 0.35A of power. With the information gathered so far I can estimate how much power I’ll need if I want to run this light for a certain amount of time, and I can figure out how much power I can expect it to take while it’s running. If we use the Ah reading I mentioned earlier we can also understand how much battery capacity we’ve used since the last time the meter was restarted. Let’s start with that since I mentioned it.

To determine how much battery we’ve used as a percentage I’d use the following formulas:

battery capacity used as percentage = battery capacity / battery consumed

battery remaining as percentage = 100% – battery capacity used percentage

For a theoretical battery with 20AH of a capacity and 2Ah consumed the formula looks like:

20AH / 2Ah = 10% capacity used

100% – 10%= 90% capacity remaining

Now let’s add time to the mix. I’m going to use a Yaesu FTM-100D radio as an example of thinking about how much power it will use based on the specifications from the manual. According to its specifications when it’s receiving only it’ll draw 0.5A. The max power it will draw when transmitting 50W on 2m is 11A. Using this information let’s figure out how much battery we’d need to operate this radio some percentage of the time for 8 hours. For the purposes of this post we’ll call the amount of time we’re transmitting our duty cycle. We’ll assume we’ll be transmitting at 50W for 10% of the time that the radio is powered on. The formula will look like this:

Ah used = current * hours * duty cycle

While the radio is receiving only during an 8 hour operating period we’ll use 3.6Ah of battery capacity:

0.5A * 8h * .90 (90% receiving time) = 3.6 Ah capacity used

Now we should compute power usage when transmitting at 50W:

11A * 8h * .10 (10% transmitting time) = 8.8 Ah capacity used

Total power consumption over 8 hours for the radio:

3.6Ah (RX only) + 8.8Ah (TX at 50W) = 12.4Ah

When we add them up we need at least 12.4 AH of battery capacity to run that radio for 8 hours while transmitting 10% of the time. If you want to run the radio for 16 hours transmitting 10% of the time you’d either need to be able to re-charge that battery to replace the discharged power before the battery gets too low or have a battery large enough to run the radio for 16 hours, meaning you had at least 24.8 AH of battery capacity. There’s also a way to cheat on battery capacity. If you can reliably charge your battery as you run your radio from a source like a solar panel you can replace current that’s drawn down by your loads. In that case you’d just subtract the current you’re able to supply from your charging source from the load. If you end up with 0 or a negative amount of current draw you’re able to power your radio without discharging the battery.

Figuring out how much power you use as you go

This section can apply to both bench testing and operating in “the wild”. This details how you’d use any power meter that’s capable of measuring cumulative power use while you’re running loads. The Powerwerx meter I mentioned earlier and the BuddiPole PowerMini have this capability. If you connect one of these power meters inline with your setup as you operate and run loads it will add the cumulative power drawn. This can be useful when you want to understand how much power you’ve drawn down on a battery. As I write this before the 4/3/2022 Portland Neighborhood Emergency Team chat net and NET net I plan to operate on battery with lighting during the net and record my power usage here later, but the thing I do is the following for both bench testing and off grid measurements:

Connect my power meter between the power source and load as described above
Perform whatever activities I would normally perform
When done I check the consumed Ah on the meter to get my battery capacity used
Calculate battery percentage used

Formula for calculating battery capacity used:

battery capacity used / battery capacity = percentage capacity used

For an example with a 20AH battery and 15Ah of capacity used during some activity I would have 25% capacity remaining on the battery. I can use this formula in the lab to estimate how much power I’ll need in the field later, or understand how close I am to drawing my battery down in the field:

15Ah / 20AH = 75% used battery capacity

100% – 75% = 25% remaining battery capacity

Adding it all up

When you perform this kind of analysis on devices you expect to run off of battery in the field you can begin adding up all your field components and understanding what your power requirements will be. If you know your lighting will take 2Ah to run for a few hours at night and 12 hours of radio operation might cost 13.2Ah you can say your station will take 15.2Ah to operate for 12 hours. As you add more devices such as phone chargers, laptops, etc. your power requirements will change. You can also use this methodology to reduce power consumption. For example if running your radio at 5W is sufficient to achieve your communication goals you could save a lot of power, requiring a smaller battery, or less recharging capacity. You could also achieve similar results by having fewer devices or keeping your radio transmissions more brief (decreasing your duty cycle). Comparing the sums of power consumption between different setups can also help you inform either your expectations of how to operate or what is possible with the setup you have. It can also help you right-size a battery or recharging system for your specific uses.

A real-world example

I wanted to add an update with another example of operating the radio in reasonable conditions doing a specific task that isn’t entirely theoretical, or just on-the-bench testing. Tonight I was net control for the Portland Neighborhood Emergency Team chat net, and I also participated in the Portland NET net as well. For most of the nets I was running two LED lights and I topped the last 25% of my tablet’s power off. I ran my Kenwood TM-V71A at 5w which drew about 3A when transmitting and 0.55A receiving. Both of the LED lights were set on low and consumed 0.1A apiece. The charger’s power usage varied depending on the part of the charging cycle the tablet was in, but at the end of 3 hours of running the radio, and about 2 hours of running both lights I used a total of 3.42AH of battery capacity. The battery I was using has a rated capacity of 40AH, so I used about 8.6% of its capacity (3.42AH used / 40AH of battery capacity = 0.086) doing both nets and listening on the first net’s frequency for an hour before it began. The first net that I was transmitting more on used the majority of the capacity, about 2.3AH. During the second net I only used about 1.1AH because I spent the vast majority of it listening as we ran lights and the tablet charger.

Tying it all together

By the end of this blog post I hope you came away with a good understanding of how I approach understanding and estimating my power usage and right-sizing my equipment for specific uses. This approach also helps inform how I operate when I don’t expect to have reliable power or when my situation changes and I’m not able to recharge batteries, etc. It can also show you how big of a difference it can make when you transmit less or when you add or drop devices from your setup.

This pattern can potentially be applied to other equipment like medical devices that can be run on battery. I’ve used the same method to profile my partner’s CPAP machine’s power consumption with various settings. I’ve been able to determine what sort of battery and charging system that will be required to keep it running when grid power fails or is unavailable (hint: turning off the humidifier and tube heater really saves a lot of power).

Notes after the fact

On the advice of Kevin, N6KVN I’m going to add a note about batteries. While this bit of the post is a bit out of scope it’s important to touch of the strengths and limitations of various battery technologies. Some batteries can be damaged by discharging them to 50% and others can be discharged to 20% or possibly lower before damage occurs. It’s important to understand the characteristics of the equipment you’re running. If you’ve read other posts of mine you’ll notice that I field a lot of LiFePO4 batteries. One of the reasons (apart from weight and other safety factors) that I tend to use them is because they can be discharged to a depth of 20% of remaining capacity before they’re permanently damaged. Most common lead-acid battery tech (think car batteries) can only be discharged to 50% before permanent damage to the cells occurs, but they are much cheaper than lithium batteries. Comparisons of various battery types is an entire post of its own, but these things are worth mentioning as you size your system and plan for the amount of energy you expect to discharge or plan to use. As an example my 100AH battery really has a usable capacity of 80AH because if I were to discharge the battery to 20%, or 20AH it would cause permanent damage to the battery (100AH capacity * 20% limit = 20AH, 100AH capacity – 20AH limit = 80AH of discharge before damage). This information should be listed by the battery manufacturer. If it’s not included I’d recommend reaching out to their support team.

Attempting HF QRP operation in NE VT

Operating, Travel

Howdy! This post is one that’s been in the drafts list for a hot minute, but I took a trip to NE VT to visit a partner and on valentine’s day we went out in the woods behind her place to radio for a couple hours. After a hike that seemed much longer up hill than down we arrived a higher spot with a clearing that would allow me to set the Superantenna up. I wanted to test my new Yaesu VX-6R with a Mobilinkd TNC3+ for APRS operation. I was hoping to make some contacts with Canadian stations since I was less than 1.5 miles from the border on the hike, but alas I don’t have something set up right.

To add a bit of fun the shoulder strap on the Superantenna bag failed as seen in the photo below as we hiked up. Unfortunately that meant we had to hand carry the unit up and back down.

Radio equipment and a glove sitting on top of a snow bank in woods with deciduous trees and brush in the background. — QRP station set up in the woods of Northern VT

A Lab599 TX-500 radio sitting on top of an ammo can with a Kestrel portable weather station reading 26.3F. The radio is connected to a duplexer which is laying on the snow. — HF radio set up for 20m in 15-20F weather depending on the cloud cover.

After getting the setup ready to rock I tried some phone operations on 20m SSB, but was ultimately not able to make any contacts despite being able to hear a number of other stations. There was a contest going on so it was hard to reach other stations. I haven’t been having a lot of luck with the Superantenna lately apart from using for SWL. I kept the 4.5AH Bioenno battery wrapped in a warm shirt within my black Chrome bag to keep it as warm as possible rather than leaving it in the ammo can. I just ran the power cable out of the top of my bag and left it rolled up when we found the spot to set up. The only ill effect the cold seemed to have on the TX-500 was that the LCD screen was a touch slow to respond to changes, but I was able to tune to stations without issues. I was surprised not to see a bunch of frequency drift despite the weather.

A Yaesu VX-6R and Mobilinkd TNC3+ sitting on top of a bag on a snow bank with some RF fittings and cables visible in the background. — Yaesu VX6R and Mobilinkd TNC3 on duplexer for APRS.

I used the VX-6R with the Mobinlind TNC3+ in conjuction with a duplexer going to the Superantenna with a 2m load coil set up.

A Superantenna is set up with a 2m coil installed on a tripod. Trees and brush are visible in the background.

Superantenna and Chameleon Mil Whip 2 set up for 20m and 2m operation

In conclusion I made no contacts whatsoever and it was cold as hell, but it was a fun hike/bushwack and my winter gear held up very well against the cold. I’d like to try this again someday, but with the trail friendly 10/20/40m endfed. I also have more experimentation left to go to get my Mobilinkd TNC3+ working properly to do APRS. As a note it wasn’t nearly as difficult to deal with the Superantenna ground plane wires as I thought it might be. The main problem I had was that I’d wound them in a way that allowed them to get tangled up and deploying them was difficult. Rolling them back up wasn’t too difficult even when the sun was behind cloud cover.

Camping in the Tillamook State Forest (1/21-23/2022)

Camping, Operating, Stories

It’s been a while and this will be a big post! My partner and I were able to go camping over the weekend, and if you’ve read any of my blog posts you won’t be surprised that I took the opportunity to practice some comms and off grid operating. I wanted to work HF, do some shortwave listening, and see if I could do any UHF/VHF communications. Additionally I wanted to run off of the 100AH battery box for a couple days to see how well it held up under constant use. This is also the first camping trip I brought the speaker stand antenna mast setup on.

On the way out I ran APRS with the Kenwood TM-D710G and the COMET-NCG CA-2X4SR antenna that mounts on the hood of the 4Runner. I noticed that on the way out that I had APRS coverage nearly the whole way out.

The first night we arrived late so I did a bit of SWL. I mostly got Radio Havana Cuba, Radio Nikkei, a distant station broadcasting in Mandarin, and Radio New Zealand International.

The next day I set the antenna up following a fun walk in the woods below the camp site. Most of my work on HF was done using the usual Endfedz Trail friendly 10/20/40m antenna. I strung it between the 4Runner and my portable antenna mast. I also added a 6m end fed dipole to the setup to see if I could reach Kevin, K7AJK from my camp site on the Lab599 TX-500. We had no luck. I wasn’t actually able to make any voice contacts on 20m with this setup even running at 10W, but there was a contest on the band so it was both congested and I suspect folks were running at fairly high power levels to make contacts. As you’ll be able to see from photographs I did a little hack with a stick I found to push the antenna higher off the ground on the truck side. It was especially helpful in preventing the hatch back from striking the antenna.

View of an antenna mast guyed to the ground and a line with an antenna running to a SUV in the background — Guyed antenna mast with two antennas added

View of an SUV with a piece of wood lashed to the roof rack holding some paracord off of the top of the vehicle. — Found piece of wood used to push the antenna higher off of the roof of the 4Runner

An antenna tied to paracord running from the upper-right corner of the photo to a mast several feet away on the edge of a hill. The transformer for the antenna is visible with feed line hanging down. Forest in the background. — The Trail Friendly Endfedz is strung along some paracord to prevent damage to the antenna if the mast blew over.

After a few hours of having no success running phone I decided to switch to packet. Moving the radio into the vehicle reduced the SWR and allowed me to run the entire setup from the 100AH battery since I had used the 4.5AH battery quite a bit for SWL already. I had also been simultaneously been running my 2m rig and APRSDroid on the tablet connected via Bluetooth to the mobile radio with a Mobilinkd TNC3+. I was able to send a number of text messages back and forth between friends using SMSGTE, which was nice given the complete lack of cell service. At this point I was still using the antenna on the truck.

A Raspberry Pi connected with a Lab599 TX-500 radio via two cables sitting in the back of a 4Runner. — Lab599 TX-500 connected to the off grid Raspberry Pi

A tablet sitting on a metal camping table running the JS8Call application. — Tablet running JS8Call

A toolbox with power connections running from it sitting in the front seat of a vehicle. — 100AH battery box connected to the Kenwood TM-D710GA in the vehicle, the Lab599 TX-500, and some lighting.

After quite some time operating on digital I decided to test some configuration changes I made to js8cli to increase the accuracy of maidenhead coordinates I was submitting to APRS-IS via Internet-connected stations running JS8Call. I had some pretty good luck as my position was accurately reported.

A photograph of the screen of a tablet showing the JS8Call application running. A callsign, timestamp, and 10-digit maidenhead coordinate are displayed prominently in the photo along with a screen showing contacts with other stations. — JS8Call screen shot showing a 5-level maidenhead position set via js8cli running an daemon mode

A screenshot of the website aprs.fi showing a Google satellite map with a rectangular marker for K7JLX placed in a clearing. — My position as displayed on aprs.fi

Apart from all the fun I had on HF, and walking around the forest with my HT (where I was reliably digipeated at 5w) I also figured I’d try to see if I could hit some of the repeaters in the Portland area, so I swapped the vertical antenna on the vehicle for my collapsable J-pole and speaker stand antenna mast. Much to my surprise I was actually able to get into the repeaters in the Portland area at 5w, but it was a bit sketchy as sometimes they wouldn’t key up. Apart form that I could get a bunch of APRS stations and digipeaters as well as some folks on the 2m calling frequency. I actually ended up having much better luck on 2m than on HF this time around.

The head unit of a Kenwood TM-D710GA radio placed on the dash of a vehicle. — Kenwood TM-D710GA on the dash of the 4Runner

A 4Runner with an antenna mast tied to the front bumper and connected to the vehicle with feedline. There's a camping table and chairs to one side and in the background are trees, a valley and a mountain on the other side of the valley. — The 4Runner antenna hood antenna swapped for an elevated J-Pole on the speaker stand mast.

Close-up of paracord tying the the antenna mast to steel tubing on an offroading bumper. — Using paracord to lash the antenna to the bumper of the truck

As you might have noticed from the pictures above I ended up moving the antenna because winds were getting higher and I was afraid the antenna might move side-to-side on the bumper’s tubing. I ended up shifting it toward the driver’s side where I could secure it to both the tube running horizontally and to the spot where the tube split, meaning the mast wouldn’t shift from side to size because it was secured with the paracord on both axes. since the antenna mount on the vehicle uses the same connector as most of my coax and the J-pole I was able to just connect the J-pole directly to the existing cabling in the 4Runner. Easy!

For the entire trip apart from doing some SWL with the TX-599 on its 4.5AH battery away from the truck and by the fire ring I ran all the lighting and radios from the 100AH battery box. We charged the tablet, my partner’s phone, and my phone from the battery box as well. We only drew down to 96% in two days. One day had a lot of heavy radio usage as well so that’s all a good sign.

Yellow witch's butter growing from the top of a tree stump with diamond cut patterns.

Some witch’s butter we found on a stump near our camp site

Bench testing 100Ah battery box improvements

Bench test, Not actually radio related

Battery box sitting on a concret slab with wires running from it. — Battery box with solar power and a 90W USB charger connected via a PWRNode

Zoomed out view of the battery box with a wire running to it from the right that's taped down, a laptop on a bench near the battery box with wires running into it from the battery box. — A wider view of the work area with the solar cable taped to the ground and the laptop on a workbench

With a potential COVID-19 exposure I decided to work outside in order keep my housemates’ exposure as low as possible. This afforded me the perfect opportunity to test running a high performance laptop from my batery bank and on solar power. I wanted to bench test integrating a West Mountain Radio Epic PWRGate into the existing battery box that had been intentionally designed without and integrated charger. The first and second days of the test with good and poor sunlight respectively went well. The solar panels were holding the battery up and by the time I was done working the battery was fully charged. It is worth noting that earlier in the morning the laptop was running on the battery, but as the sun came up the battery began recharging in both cases. Of course the battery charged more slowly and sometimes went into a discharging state on the cloudy day but ultiately all the power drawn from the battery was replentished.

Two powerpole ports populated with power cables on the power box's side. — The added solar (left) and UPS (right) powerpole connectors

View of closed powerpole ports, two populated powerpole ports, and a red disconnect switch as seen from the corner of the battery box. — The existing 30A charging port (top), added disconnect swtich for the charger (middle), and added DC in port (bottom)

I added three new Powerpole ports to support the installation of a West Mountain Radio Epic PWRGate for use as a multisource battery charger and to allow one port on the battery box to function as a UPS, one as a DC charging input from a vehicle or other 12v power supply, and a solar panel input that can work with lower voltage (<30V) solar panels. I also added a charger disconnect switch that prevents the charger from acting as a parasitic load when it’s not in use. The specific disconnect switch I added allows the red rotary part of the swtich to be removed n the event you want to make sure the charger isn’t connected to the battery by mistake.

Open battery box revealing connections between internal components including the Epic PWRGate. — Opened battery box with the Epic PWRGate connected for testing

The Epic PWRGate connects to the ports with 10GA stranded copper wire to support 30 amp loads. The “battery” port on the PWRGate is connected to the battery via the DC disconnect switch and the DC subpanel. The leg of the circuit that connects the battery to the charger is also fused with a 30A fuse to allow it to operate a full power radio via the UPS port. The Epic PWRGate will charge a battery with a max current of 10A. I also added an optional temperature probe connected to the positive battery lug that will cut the charger off when the battery gets too cold or warm to prevent harm to the battery. The temperature parameters are configurable using the USB port. The appropriate USB cable, USB C, and USB A OTG cable adapters are included to connect a device with a serial terminal emulator installed.

This updated simplified build diagram for the 100Ah battery box includes the modifications that were being bench tested and will likely remain as a permanent addition to the system for charging from a vehicle or charging from a lower voltage (<30v) portable solar panel.

As a side note an added advantage of including a charger like the Epic PWRGate to this setup is that it can be re-configured to charge another battery, even of a different chemistry from the 100Ah LiFePO4 battery. You can charge a smaller battery or even charge a lead acid battery from it as well. This will require changing jumpers if you’re not programming the unit with a USB port, but I prefer programming it with a USB port as I get a better degree of control over the settings such as charge current than the onboard jumpers provide. It will also require swapping the battery and DC ports. The battery should be connected to the DC port and the DC port should be connected to the battery being charged. In the event the charger is re-configured I also include the custom LiFePO4 battery settings for my Relion RB100 that the kit is designed around so they can be restored on the charger without requiring memorization.

Solar panel suspended from paracord in the sun. — Suspended foldable solar panel

I also ended up having shading issues in the space that was available to set up the solar panels so I used the built-in eyelets and some paracord to suspend the panel in the sun to avoid shading on the ground. I was also able to slide the panel laterally on one piece of cord running left to right (east to west) near the water tank pictured. The other piece of paracord goes through both of the eyelets and forms a tiangle whose point is a knot and the single line of paracord runs back to a single anchor point from the triangle, and is pointed south. You can slide the panel side to side on the paracord running right to left (east to west) as the sun’s position in the sky changes. Getting the panel off the ground was extremely helpful because it got the system out of shadows cast accross the ground most of the day, and also required less maintenance as shadows tracked across the ground and threatened to partially or fully shade the solar panels. Instead the shadows were cast under the suspended panel.

The 100W folding panel was able to charge both a 19″ Macbook Pro connected to a 90W USB C car charger and a phone the an entire work day. This worked well on a bright day and on a cloudy day using this new configuration. I leverage MC4 connectors for the 100W panel to harden the connections against rain and dust. They’re adapted to Anderson Powerpole connectors for connection to the battery box using a pigtail I store in a zippered pouch on the back of the folding panel along with rolled lengths of wire with MC4 connectors attached.

This is an update to this post about building the battery box.

Using the portable LiFePO4 battery banks in the Gifford Pinchot National Forest

Operating, Stories

This won’t really be a post about doing a lot of operating. It’s mostly about powering and recharging stuff. The long story short of operating from the specific site we were at is that I didn’t make any contacts apart from another station on JS8Call that heard one of my heartbeats. I wasn’t in a good position to be heard, but I could hear a lot of other stations on 40m throughout the afternoon and evening. I was also able to hear Radio Havana and what I suspect might have been Zambia NBC Radio 1 for a few minutes.

I was able to recharge the Bioenno 4.5Ah battery in an hour or so as we broke camp and packed the vehicle. I’d been using that radio the previous day and listening to shortwave stations the whole night. A solid hour of charging at 1.1A using the BuddiPole PowerMini on a single GoalZero Nomad 20 solar panel was enough to replentish the battery.

The 100Ah battery was easily charged in about 45 minutes. We’d only drawn about 3.5Ah from the battery running lights, charging a phone, and a portable projector. The panel in use here is a Bioenno 100W folding panel and from the VictronConnect application screenshot it’s charging at about 4.5A. The back view shows how the solar panel is connected to the charging unit and the battery. This is the first time I’ve used the West Mountain Radio Epic PWRGate to charge the 100Ah battery. I’m hoping to use it for charging from a vehicle alternator, an existing DC power supply, or solar panel. I’m also hoping to add a charger like this to the box along with a temperature probe to ensure the battery isn’t charged when it’s too hot or cold. The Relion RB100 has a minimum charging temperature of -4F.

This a detailed view of the West Mountain Radio Epic PWRGate. The green LED indicates it has good solar charging voltage, and the blue LED that was slowly pulsing which indicated that the battery was being bulk charged by the solar panel. The PWRGate is programmed with the specific battery chemistry settings for LiFePO4 batteries and is current limited at 6A for some of the other batteries I charge with this setup.

Exploring the Tillamook State Forest and doing nets

Camping, Operating

This post has been a long time coming, and was delayed by the post about the battery box as well as some sudden health issues my partner and I’s furry companion was dealing with. Unfortunately this would be one of his last trips he took with us but it was extremely enjoyable and we had a wonderful time exploring / sniffing everything depending on who you were. Loki was an incredible companion who visibly cared about not just the humans he lived with but all humans, especially folks that were sad or distressed. He is deeply missed by many around him. Rest in peace Old Man.

As we have been exploring with our vehicle I’ve also been testing various scenarios operating the radio. I wanted to see if I could hit the K7LJ repeater on Mt. Tabor in Portland from this camp site so I set up my portable antenna mast, connected my radio to the newly-constructed 100Ah battery box. I messed up connecting the radio at first, but later saw my current draw while the radio was idling was higher than expected and fixed the issue. More on that later.

The net went fine and I had a decent signal report, but my audio was a bit low due to the headset I was using. Increasing the sensitivity resolved that issue after the net had concluded. I’ve noticed that specific Heil headset tends to require more preamplification to produce quality audio for recieving stations on most of my radios. This specific site was somewhere around CN85ho17.

I was able to reach the repeater with little issue and a decent signal report. Being this far out and in the mountains that was a pleasesent surprise.

View of the battery connected to the radio

View on the table with the radio’s head unit and headphones extended from the vehicle

At this point it’s worth pointing out a mistake I made when connecting the radio to the battery. I saw about 1.5A of current draw when I was expecting to see about 0.6A. It’s important to make sure you connect the battery to the radio and to make sure you’re not energizing your vehicle’s electrical system with the battery. You can easily damage things and burn fuses out if you do that. I noticed the current draw was higher than it should be if I were just powering the Kenwood TM-D710G and investigated the electrical setup. I had disconnected the wrong end of a “Y” cable that splits between the Kenwood radio and the CB radio I use for offroading/trails. I had accidently energized the vehicle’s electrical system when it had some accessories powered on. Lesson learned.

Extender connected to the Kenwood radio base unit and to the headphone adapter / radio display

100Ah battery box build

Howto, Theory

Ok, so this is a big one. I wanted to build a battery box that could keep me going a few days without being able to charge while camping and/or operating. I also wanted accurate power accounting and the ability to understand my power consumption and have alarms when usage exceeds specified thresholds, providing the opportunity to either adjust usage or in an emergency not be surprised when I drop out. I also wanted to design the system for maximum flexibility when it comes to charging and connecting loads. Most commercially-available systems that met capacity and power needs were designed around inverters and larger 30+ volt solar panels that were designed to mount on structures or large vehicles like RVs or vans rather than the smaller and more portable 18v open circuit foldable panels that are used more commonly for my purposes. Having a wider range of panels that I can use is better because it would be good to charge from either so not building in charging was ideal. I also found the options for high-amperage DC connectors lacking in many pre-built options. Some units would have one or two 25A outputs, but those are at the max current range some of my radios will draw at full power. I wanted some breathing room current-wise. In the event I wanted to operate one of my bigger radios at full power I’d rather not risk burning a fuse out or damaging my power source – especially in the field while I’m relying on it. It’s also nice to have many connectors available on the source which eliminates the need for a bunch of splitters. None of the commercially-available options I evaluated provided more than two high amperage connectors. Finally, I wanted a couple USB fast chargers for my and my partner’s devices which many commercial options provided, but they’d typically provide a single fast charging port.

I took some inspiration from a Powerwerx box that a fellow ham and NET team member Laura, KI7ZZQ purchased. That battery box was designed to accommodate a 50-70Ah battery which wouldn’t physically fit any of the 100Ah batteries I had been considering during the design phase, but it provided me a rough template I could build from in terms of layout. As with that box just including power distribution and monitoring in the box was a way I could reuse existing systems I have that perform well without having to buy more of those components. Buying a bunch of new parts is pretty expensive so not including more core devices in the box is definitely a plus.

This was not a cheap project, but I think it’ll be worth it.

Theory and design

By selecting a 100Ah battery I get 80Ah of usable power from the system without significantly decreasing the battery’s lifecycle. Using LiFePO4 batteries instead of lead-acid means I get an additional 30% depth of discharge without the destructive effects of discharging to 50%… The LiFePO4 battery I selected also weighs 26lbs. A similar capacity lead acid battery would weigh a lot more and probably require a much sturdier and expensive enclosure. Another advantage of LiFePO4 batteries is the lack of battery memory – that is to say the useful lifetime of a battery isn’t diminished by leaving it in a partially-charged state. Some battery technologies suffer from that problem which is a problem if you’re in a situation where you might not be able to completely recharge the battery completely during use. As far as parts go I wanted to attempt to source the parts I didn’t already have from a variety of vendors… I had a preference for smaller and more local vendors, but that didn’t work out 100% of the time. The enclosure (tool box) and a 1 1/8″ hole saw are two examples of where that didn’t work. The bill of materials will list the source of each component.

So let’s start with the system design itself. There are a few core components that I knew I’d probably want from designing a bigger high amperage system when my partner were considering purchasing and building out a van for camping/touring. The core parts that everything else would be designed around are:

100Ah LiFePO4 battery
Reliable battery state and power usage monitoring capability
Battery disconnect for safety and preventing parasitic loads from draining the battery
Circuit breaker for the battery to prevent damage to components or fires
DC subpanel to split out and protect branch circuits
Two switched USB rapid chargers.
Flexible charging – AC-to-DC chargers (wall socket, generator), solar panels of various types, and DC-to-DC (vehicle, independent DC power supply, DC generator outputs)

Those components are roughly connected and arranged as follows. Chargers can be connected to any of the powerpole connectors listed below, and so can loads. The only loads that wouldn’t be connected to powerpole connectors are devices directly connected to the built-in USB A/C rapid chargers. You’ll notice there’s a power line running from the battery to the 500A shunt resistor and power supply that feeds the Victron BMV-712 through a 100mA fuse, bypassing the circuit breaker which also doubles as a battery disconnect. That’s intentional as the BMV-712 requires constant power to track battery state and if powered off it will lose its zero-point configuration. This is the only parasitic load that isn’t switched in this system apart from the BMS built into the battery, but it’s required to get accurate battery status so I compromised.

Block diagram showing electrical connections between a battery, shunt resistor, circuit breaker, DC subpanel, USB chargers, and power connectors.

Materials / parts

High amperage and distribution components

Description	Qty	Make and model	Vendor	Link	Notes	Tool?
100Ah LiFePO4 battery	1	Relion RB100	LightHarvest Solar	Here		N
Red #2/0 welding cable, 10′	1	?	—	Here		N
Black #2/0 welding cable, 10′	1	?	—	—		N
100 amp circuit breaker *****	1	Eaton 285100F	—	Here		N
6-position 100A DC subpanel	1	BlueSea 5025	—	Here		N
Hammer-type crimping tool	1	TE(?)	—	Here		Y
Battery monitor	1	Victron Energy BMV-712	—	Here		N
#2/0 Lug Ring Terminal (5/16″) *	3	?	—	Here		N
#2/0 Lug Ring Terminal (3/8″) *	3	?	—	—		N
#2/0 Lug Ring Terminal (1/4″) *	5	?	—	—		N
10A LiFePO4 14.6v battery charger	1	Bioenno Power BPC-1510A	Bioenno Power	Here	Dedicated AC-to-DC charger	N
Tool box	1	Dewalt DWST24082 One Touch Tool Box, Black	Home Depot	Here	Used as enclosure	N
#10-24 3/4″ cap screws and nuts (x8?)	1	?	—	Here		N
#10-24 1″ cap screws and nuts (x6?)	1	?	—	Here		N
#10-24 Bonded neoprene washer (x4)	3	?	—	Here		N
1 1/8″ hole saw	1	?	—	Here	Used for Powerwerx panel mount devices	Y
Panel mount powerpole socket (x2)	2	Powerwerx PanelPole2	Powerwerx	Here		N
Panel mount powerpole socket (x1)	1	Powerwerx PanelPole1	—	Here		N
USB A QC + USB C PD charger, panel mount	2	Powerwerx PanelQCUSBC	—	Here		N
Bonded 10GA stranded copper wire, 25′	1	Powerwerx Wire-RB-10-25	—	Here	Used for 30A branch circuits	N
Bonded 14GA stranded copper wire, 25′	1	Powerwerx Wire-RB-14-25	—	—	Used for 15A branch circuit	N
Powerpole to “cigarette lighter” adapter	1	Powerwerx SOC-PP	—	Here	Stored in the enclosure as an adapter	N
4-Way powerpole splitter	2	West Mountain Radio PWRNode	Ham Radio Outlet	Here	Used as splitters for the 2x panel mount powerpole sockets	N
Panel mount rocker switch w/red LED, 15A max	1	Powerwerx PanelSW-Red	—	Here		N
15/30/45A red powerpole housings	6	Powerwerx PowerpoleCase	—	Here		N
15/30/45A black powerpole housings	6	—	—	—		N
Powerpole retention clips	6	—	—	—		N
45A powerpole contacts	22	—	—	—		N
Powerpole crimper	1	Powerwerx TRICrimp	—	Here		Y
F2 blade connectors, 12-10GA	3	?	?	?		N
F2 blade connectors, 16-14GA	4	?	?	?		N
Lug ring terminal, 12-10GA	6	?	?	?		N
Lug ring terminal, 16-14GA	2	?	?	?		N
7.5A ATC blade fuse *	3	?	?	?		N
30A ATC blade fuse *	5	?	?	?		N
Assorted ATC blade fuses	6	?	?	?	Included in enclosure	N
Packing foam **	?	?	?	?		N
Electrical tape ***	1	?	?	?		N
1 1/4″ bolt and flange nut ****	1	?	?	?		N
Zip ties	5	?	?	?		N
3/16″ (?) drill bit	1	?	?	?	Used to drill holes in plastic fins in toolbox for zip ties	N
Electric drill	1	?	?	?	Used w/hole saws and drill bits	Y
2″ hole saw	1	?	?	?	Used to drill a hole for the Victron BMV-712 panel	Y
Phillips screw driver	1	?	?	?		Y
Metal shears	1	?	?	?	Used to cut #2/0 welding cable	Y
Diagonal cutters	1	?	?	?		Y
Socket wrench	1	?	?	?		Y
?mm socket	1	?	?	?	Used for shunt bolts	Y
?mm socket	1	?	?	?	Used for battery terminal bolts	Y
?mm socket	1	?	?	?	Used for #10 nuts	Y
?mm socket	1	?	?	?	Used for DC subpanel 100A contacts
Needle nose pliers	1	?	?	?	Used to help pull wires, tighten panel mount nuts	Y
Claw hammer	1	?	?	?	Used w/ the TE hammer-type crimping tool	Y
Pocket knife ******	1	?	?	?		Y

Legend
? Can’t remember/unknown
— Same as above
* Includes spare(s) or extra(s)
** This is small-cell plastic foam used as packing to keep the battery from moving around a lot
*** Used mostly to bind wires and as extra insulation on the #2/0 ring terminals. Also used to physically shore connections up due to gaps in wire jacketing or potential stress points from bends.
**** Used as insurance to hold the toolbox closed in case the latch is opened unintentionally
***** Doubles as a battery disconnect switch
****** Used to clean plastic burrs left from the hole saws and to cut the jacketing on the #2/0 cable in preparation for crimping

Assembly

This was done in a a couple phases – in part because I was waiting for things to come in the mail, and in part because I sort of “winged it” building this out in terms of mounting components to the enclosure. The first thing I did was pick locations for each of the high amperage components: the battery, BMV-712’s 500A shunt, 100A circuit breaker, and the DC subpanel. I made sure to allow for enough space to run cables to and from each component before drilling holes for them. The battery was pushed to the left side of the tool box. This makes it a bit awkward to carry but creates enough space in the right side to mount everything.

Once I found a good placement for the components that required mounting I just drilled holes in the enclosure using the components as a template. For each component I drilled an initial hole and inserted one of the #10-24 cap screws in the hole to hold it. I then drilled out a second mount and placed another bolt in it. After I’d placed all the components and got the holes drilled for them I added the #10 bonded washers with the neoprene side on the outside of the enclosure. To minimize jagged edges from threads on the outside of the enclosure I put the phillips end of the cap screws on the outside as well. The nuts and lock washers were placed on the inside.

The next step was to route, measure, and cut the high amperage #2/0 welding cable between each component. I did a dry run of the cable from component to component and cut each piece to length. I ran a piece of from the negative battery post bolt to the BMV-712 shunt battery terminal, cut it, ran another piece from the shunt to the negative terminal of the DC subpanel to the BMV-712 shunt load terminal, and cut it. I then took the red #2/0 welding cable and ran it from the positive terminal on the DC subpanel to the 100A circuit breaker, cut it, and then ran another piece from the circuit breaker to the positive battery terminal, and then cut it.

For each piece of #2/0 welding cable I cut I stripped enough jacketing off of the end to fix the appropriate #2/0 lug ring terminal to the wire. Make sure the hole on each lug ring terminal matches the post you’re planning to connect it to. It’s worth double-checking before you crimp since each section of wire is cut to length. After verifying that I was using the right ring terminal for each connection I crimped them to the #2/0 welding cable. I then wrapped the bare metal parts of the lugs that might be prone to shorting with electrical tape since I didn’t have any heat shrink tubing. I also used the tape to shore the joint between the jacketing of the welding cable and crimp-on connector.

The next step is to hook the high amperage wire up to each component. This will help us figure out where to run the legs from the DC subpanel and to help us properly place the panel mount components without interfering with the high amperage wire runs and components mounted inside the enclosure. Before making the connections between components verify the polarity of the connections and break the circuit by pressing the reset button on the circuit breaker. The connections should be made according the the simplified wiring diagram above.

Completed mounting of all components in the lower portion of the enclosure

The next step is to place and mark each panel mount component. I chose to mount the BMV-712’s meter on the front of the tool box to the right of the latch since I mounted the DC subpanel on the flat part of right end of the toolbox. I mounted the 1x powerpole panel mount component on one of the angled surfaces on the right end of the enclosure so I could connect a charger easily when it’s stored on a shelf. I picked spots for the panel mount components on the lid because I think that’s going to be the easiest spot to make connections in the field. All the panel mount components were placed in such a way that the panel mount nuts cleared the plastic “fins” on the inside of the enclosure. Special care should be taken when placing components in the lid. There are a lot of plastic fins on the inside of the lid. Use the 2″ hole saw to cut the hole for the Victron BMV-712’s meter, and for all the other Powerwerx panel mount components use the 1 1/8″ hole saw. You might need to shave the decorative raised lines on the lid down with a pocket knife to ensure that the panel mount components mate to the outside of the lid properly.

Photo showing placement of all panel mount components

At this point it’s time to start making the connections from the subpanel to the panel mount powerpole connectors. Since I used 10GA wire capable of handling 30A it’s hard to daisy chain between ports so I opted to use some PWRNode splitters to make the connections to the 2x panel mount powerpole sockets. I made some shorter 2″ stubs of 10GA wire and crimped 45A powerpole conductors on both ends of each stub. Connecting all 4 ports requires 8 2″ stubs. Once I crimped the 45A conductors on I added the powerpole housings to one side of each stub. The other side of the stub was inserted into the panel mount connector. Each panel mount socket is connected to a single run of cable from the DC subpanel with powerpole connectors on the end of it. The idea is that each socket can support up to 30A of total current draw. Once that was complete the side with the housings were connected to the PWRNodes and powerpole retention clips were installed to keep all the powerpole connectors in place. The 1x powerpole connector was run directly to the DC subpanel. Each leg was then fused in the DC subpanel with a 30A fuse. I used some electrical tape to support the “joints” between the powerpole connectors that lead to the DC subpanel and the powerpole connectors themselves.

The next step in wiring the system is to connect the panel mount chargers in parallel and switch them with the rocker switch using the 14GA wire. This is accomplished using the connections as detailed in the simplified electrical diagram. The brass connector on the switch connects to the ground, the middle connector connects to the DC subpanel, and the silver connection on the end connects to the USB chargers wired in parallel. The photo below details how the connections to the panel mounted devices and sockets. I drilled a hole in one of the fins on the lid of the toolbox and wire tied the wires coming from the DC subpanel to the lid to keep the wires from migrating a lot during transport. I also used wire ties to hold some of the wires together coming out of the individual parts.

Now that all those connections are complete we can re-connect the battery, and while we’re at that we’ll hook the BMV-712 up. The BMV-712’s box has a handy connection diagram. In this step we’ll connect the battery and the BMV-712. First connect the BMV-712’s red (positive) wire connected to the temperature sensor lug to the battery using the ring terminal along with the terminal on the #2/0 welding cable. Both should connect directly to the positive battery terminal. Take care not to short the pin end of the BMV-712’s red power cable while connecting it. Once that’s connected to the positive battery terminal connect it to the B1 pin on the BMV-712’s shunt, and connect the black temperature monitor cable to B2 on the BMV-712’s shunt. The BMV-712’s manual will detail how that connection should be made. Now connect the gray 6-pin modular data cable from the shunt to the BMV-712’s panel mount meter. Once that’s been hooked up you can connect the negative battery terminal to the black wire leading to the battery side of the BMV-712 shunt. When properly connected the panel should light up blue and the display should become active. [Note: this was updated to include directions to connect a BMV-712 temperature sensor.]

Once all these connections are made and the battery is re-installed make sure you install a 7.5A fuse in the subpanel on the leg that connects to the USB chargers. If the 7.5A fuse blows during testing one or both of the USB chargers are wired backward. Use the + and – on the bottom to properly wire the positive and negative sides of the charger. Install 30A fuses on each leg that leads to powerpole panel mount sockets.

Now we’ll pull the yellow reset bar on the breaker back in to energize the DC subpanel. Once the subpanel is energized we can test the USB charger leg of the circuit by activating the toggle switch. The red LED should activate on the toggle switch, and both USB chargers should show their voltage with blue numerical LED displays. If all three of those work that’s wired correctly.

As a bonus I added some scraps of plastic closed cell packing “foam” around the battery to dampen vibration and shock to help hold the battery in place.

The installation is complete we can move onto programming the Victron BMV-712.

Configuring the Victron BMV-712

At this point we should set up the battery monitor. Some of the instructions in this section come in part from instructions provided to me by LightHarvest Solar. I modified some of the values in the configuration to better fit my use-case. The instructions in this section assume you’ve charged the battery completely using an appropriate LiFePO4 battery charger. I used the Bioenno charger listed in the bill of materials to fully charge the battery before configuring the BMV-712. To begin you’ll want to install the VictronConnect app on a device that it supports which also has Bluetooth. There are versions for IOS and Android.

After opening the app you’ll want to select your BMV-712 and pair with it. I also recommend changing the BMV-712’s pin to make sure someone doesn’t pair with it and modify its settings, especially if you’re around RVs or others with a Victron battery monitor. You can then modify the settings on the device. The major configuration tasks to do are configuring the parameters for your battery and doing a zero-point reset once your battery has been fully charged. To begin with we’ll configure the battery monitor with the properties of the Relion RB100. You can leave all the settings as defaults unless they’re specified below. I got the initial values and instructions to configure the battery monitor from LightHarvest Solar. It was provided with the purchase of the BMV-712. After opening settings and choosing “Battery” set the following:

Battery capacity: 100Ah (this is a 100Ah battery)
Charged voltage: 13.9V
Discharge floor: 20% (This is the lowest capacity you want the battery at)
Peukert exponent: 1.00
Charge efficiency factor: 99%
Current threshold: 0.10A
Time-to-go averaging period

Optionally, you can configure alarms for the system. I turned on the alarm buzzer and set the “Low SOC alarm” to go off at 40% and clear at 45%. Since you don’t want to draw the battery down lower than 20% I picked 40% to give me a warning well before I draw it down. If you draw the battery down below the discharge floor it can be damaged. You can also optionally configure a temperature alarm if you have the BMV-712 battery temperature sensor. See the “updates” section at the bottom of this post for details.

Once the battery has been configured and ALL loads and chargers except the BMV-712 have been disconnected you can then click the “synchronize” button, and then click “calibration”. Synchronize sets the battery state-of-charge to 100%. Calibration zeroes out the current measurement on the shunt resistor. If you disconnect the battery monitor you’ll need to redo this part of the process starting with a full charge.

Using the BMV-712

While this post is mostly focused on the app the display panel on the BMV-712 can display the status information using the arrow keys on the front panel. Navigating that is pretty easy, but I’d also recommend reading the manual as there’s more to the panel than just displaying data. The most common screens I use in the app are the device list which is used to manage Victron devices. They have an entire ecosystem of devices that can be managed and monitored from this app. I go through this to connect to my battery box. The battery box has been renamed in the settings (gear icon seen in the other screens). The status page shows you all the current stats for your battery – state of charge, voltage levels, current, and power. There’s one thing that’s cut off at the bottom which is the status of the control panel’s relays. For my configuration the relay is open since it’s not really doing anything. The history tab shows you stats for your battery over time. This data can be cleared, but it’s nice to understand what you’ve done with your battery over time so I probably won’t be clearing that until I replace the battery in the system. The trends tab is really nice to use when you’re watching your battery in real time from within the app. You don’t get data points when your app isn’t connected unless you get a Victron Cerbro GX or similar device but that’s overkill for my use-case.

Problems left to solve

There are still some problems to solve. I need to install some sort of barrier that prevents the battery from moving to the right inside the enclosure. I’m thinking about bolting a barrier into the enclosure to prevent too much movement. The toggle switch on the top isn’t weather resistant either. The toggle switch comes with a plastic cover but it’s impossible to install without the rocker switch popping out of the panel mount.

Updates

I decided to add a temperature sensor to the BMV-712 in order to make sure I’d get an alarm if the battery was out of the appropriate range to charge which is a more narrow range than the discharging temperature. The changes I made to connect the battery temperature sensor was to purchase a temperature sensor for $25. I disconnected the old wire running from the positive battery terminal to the current shunt, connected the new one, and connected the new larger lug to the battery terminal. I then connected the black wire for the temperature sensor to the open input on the shunt. After that I configured the BMV-712 to use the second input as a temperature sensor using the web application. Then I configured my high temperature trip temp to 55C and the high temperature clear to 53C. The alarm will go off 5C before the battery’s charge limit of 60C. The low temperature alarm was set to -15C and the low temperature clear was set to -13C. -15C is 5C above the battery’s minimum charging temperature limit of -20C. The connection diagram has been updated to reflect the new temperature sensor connection. This post talks about recently implemented changes to the battery box.

Operating while camping on Mt. Hood 7/31/2021

Camping, Operating, Stories

Hello all, it’s about time I wrote a post about my camping trip my partner and I took a couple weeks ago. I took my trusty Lab599 TX-500 kit, a couple 20W GoalZero Nomad solar panels, headset, and table/chair combo up camping with our “new” 4×4. I wanted to do some HF QRP and some handheld UHF/VHF operation while I was out. I brought some of the same portable furniture that I used at the beach last post since it worked out so well.

The view was pretty sweet for this one. The smoke from the wildfires made everything a bit more hazy but pretty great none-the-less.

View of a heavily forested valley from a high vantage point. In the foreground a radio is sitting on a gray metal camping table. — View while operating

While operating HF I made a number of contacts, and the solar panels kept the 4.5Ah Bioenno LiFePO4 battery built into the HF QRP radio kit charged the whole day. The first HF contact I made was with Stefan, AF6SA who was working POTA in Eldorado Natoinal Forest (K-4455). His signal was 5/6 on at about 450 miles away on 20m. I also made a contact with VA3AAA, Stanley in Ontario, Canada. I was pretty excited to reach Ontario with a low power radio. That contact was also logged on 20m. I also made a contact with the K0GQ radio club in MO on 20m. All of these contacts were made between 5 and 10w using the Trail-friendly EndFedz EFT-10/20/40 antenna strung between a couple trees about 50′ apart and about 25′ above the ground.

I switched radios and bands to see if I could get into some of the repeaters in the Portland area (I could) with my Yaesu FT3DR and a Signal Stick antenna. I ended up on 2m and caught two hams on 146.520Mhz doing a SOTA activation: K7AHR and K7IW. I think they were on Lookout Mountain, but I can’t remember and didn’t properly log it. I was running 5W for those contacts.

Tour of the radio setup at the camp site

Teaser: 100Ah LiFePO4 battery box

Uncategorized

A new project is underway: a 100Ah battery box with a smart power monitor and some good safety features. It’s based around a Relion RB100 battery with a Victron BMV-712 smart battery monitor and is designed to keep my low voltage gear and radios running for multiple days and can be combined with my existing solar charging gear or a vehicle-based DC charger. A detailed post about the build including a bill of materials will be forthcoming once I complete the build!

Black DeWalt toolbox with a side-mounted power meter and black sealed connector port on the top. — Partially completed 100Ah battery box

Car camping for the weekend

Camping, Operating, Stories

So, we decided to go car camping this weekend and naturally I decided I’d bring my QRP rig and HT (handheld transceiver). The goal was to sleep in the back of our car and cook using a propane camp stove while not paying for a camping spot. I also wanted to see how well my QRP setup worked with fewer resources including charging and little space to store the setup and supporting equipment. For this I picked my Superantenna/Chameleon Mil Whip 2.0 kit and Lab599 TX-500 kit. Neither kit includes feed line. Keep that in mind while reading…

A burning camp stove sitting in the back of a vehicle with its hatch back open in the dark. The stove has a pot on one burner with an avacado and knife roll near it. A woman stands to the left with a head lamp helping prepare food. — Cooking after we arrived at our chosen spot.

On a Friday after work we packed the car and left. A couple hours later we made it to our spot on the Oregon coast with some decent moonlight between spurts of rain. We made dinner in a fairly heavy wind out of the back of the car. We could hear the relaxing sound of crashing waves against rocks that we could barely see. After having some dinner we set up the folding mattress in the car and settled in for the night.

Waves on the Pacific ocean are visible beyond a chainlink fence with wooden posts with a gray sky. A bird can be seen flying by and the inside of an out-of-focus and open car door is visible on the left side of the frame. The sky is gray and cloudy. — View waking up from the car

After waking up and getting ready we made some breakfast and coffee on a nearby park table. We had to wait till the rain stopped to make food but I was able to make some coffee in the rain without issue. I was half way through my coffee and food when I realized I didn’t pack any feed line! Fortunately we were close to a town that happened to have a store open that morning which had a box of left over parts labeled “CB Radio Parts”. There was a small RG-58 coax cable with PL-239 ends and thus my problem was solved! I purchased the cable and got underway for our hike.

A radio sitting on top of an ammo can attached by cable to a duplexer and, Raspberry Pi 4 in a case. A small travel router is also attached by power cable to the ammo can. A number of small bags and a backpack are visible in and partially in frame. The ground is a forest floor with branches, sticks, lichens, and leaves on the ground. — Radios set up with a duplexer for VHF and HF operation

We did a short hike and as we neared the end of the hike we found a small but well worn trail leading off the main path, so we took it in search of a spot where my partner could water color and I could set up and operate. Not too far down the offshoot trail we found a fairly open patch of moss with a fallen tree that I could use as a bench. I set up the Superantenna using the ground spike for simultaneous HF and 2m operation using the Superantenna MC2 and MP1C, topping the loading coils with my Chameleon Mil Whip 2.0 for increased SWR bandwidth over the titanium whip that comes with the Superantenna kit. Unfortunately the photo I took of the deployed antenna was corrupted by the time I got to uploading it. The UHF/VHF side of the Comet CF-706 duplexer was connected to my Yaesu FT3D so I could attempt contacts on the 2m calling frequency (146.520Mhz) and monitor/send 2m APRS packets.

I tuned the antenna using my NanoVNA for 20m and started working SSB phone. I attempted to respond to a number of calls and tried calling to no avail. After 40 minutes of trying between 5 and 8.5W I decided to switch to JS8Call. I have yet to make a phone contact on my Lab599 TX-500 on any band. I’m hoping I can just chalk this up to being run over by higher power stations. As I was setting my station up for digital comms I noticed something unexpected – the maidenhead coordinates in JS8Call hadn’t been updated automatically as js8cli would normally do, and I also noticed the time on the Pi varied by a minute from my cellphone. That’s highly unusual as the GPS unit typically corrects any RTC drift that might occur. The next step was to check my GPS unit’s LED through the vent holes in the case. It’s flashing one second on, and one off. For the specific Adafruit Ultimate GPS board I run that means the GPS hasn’t acquired a lock. I waited a few more minutes and found that it still hadn’t acquired a lock and decided to check the board for any broken or loose connections. Since the entire setup allows me to disassemble it without tools I did to inspect it. I found no loose connections or other apparent issues. It was time to reboot by fully removing power as had worked sometimes in the past. Still no luck following a full power down / power up sequence! I then leveraged my phone and tablet GPS units to get a position. My phone eventually got a location and grid square using the HamGPS application, but my phone had been on and tracking satellites for the entire hike. My Pi and tablet had been off. This is interesting because I had an OK view of the sky despite the very tall trees surrounding the patch. I hoped my GPS unit wasn’t damaged or malfunctioning and decided to manually set my JS8Call location from my phone, automatically acquire a timing offset from other stations in JS8Call and move on. I had a couple stations hear my heartbeats but couldn’t make contact with any operators directly. I also attempted to send an SMS message to a friend but alas no one was hearing my transmissions as the band seemed to have closed. Overall not the best luck, but it was time to head back to the trail head so we had daylight to drive out and make camp.

An open hatch back of a vehicle loaded with bags. There is a Raspberry Pi in a case and travel wireless router attached to a battery in a bag. — Hooking the Raspberry Pi and wireless access point up for testing after the hike

Successful test of the GPS from the car without the trees overhead

I decided to hook the gear up in the back of the car as my partner got the dog ready to head out in order to determine if my GPS unit was actually broken. I hooked everything up to the big battery that was in the trunk and after a minute or so the GPS lock LED flashed once every several seconds. This indicated a lock, so I fired the tablet up, logged into the Pi, and checked the reports with cgps, a test GPS client provided by the gpsd-clients package. They lined up with where we were. Even though I could see sky clearly through gaps in the canopy the GPS unit wasn’t able to acquire satellites in the time we spent in the clearing.

A soft-sided cooler, LED lantern, water bottle, beverage in a can, and a radio attached to an ammo can by a power cable and a duplexer sitting on top of a wooden park bench. — TX-500 set up for shortwave listening (SWL) and for 2m operation with my Yeasu FT3D

After arriving at camp and rigging the car for sleeping I set the radio up for shortwave listening and got my Yaesu FT3D connected to the duplexer after this photo was taken. It was a windy and chilly but great day. It was time for a beverage and some relaxing SWL and taking in the scenery before turning in for the night. I used the same setup as I did on the hike, except with a tripod for the antenna and no radials since I was receiving only. We were able to hear a number of stations, but settled on Radio Havana English (6.0MHz if I recall correctly) since they were playing music instead of the typical religious content with creepy-sounding voices you typically hear on US shortwave stations like WRMI in this part of the US.

An antenna is mounted on a tripod in the foreground. Directly behind it is a park bench with someone sitting on it and some radio equipment with a cooler. The background is a fenced-in green area and the Pacific ocean and steep rocks in the background. — View of the setup on the park bench

Lessons learned:
– Don’t forget your feed line. I got lucky enough that I could acquire some, but if this was a disaster or if I were on a hike/camping in a remote location I would have been unable to operate.
– Even though you can see a lot of sky in an area, it doesn’t mean your GPS can acquire satellites. Be prepared with some mechanism to acquire and set your location and time for something like JS8Call.
– When documenting something take a couple pictures in case one of them gets corrupted.