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

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.

100Ah battery box build

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
DescriptionQtyMake and modelVendorLinkNotesTool?
100Ah LiFePO4 battery1Relion RB100LightHarvest SolarHereN
Red #2/0 welding cable, 10′1?HereN
Black #2/0 welding cable, 10′1?N
100 amp circuit breaker *****1Eaton 285100FHereN
6-position 100A DC subpanel1BlueSea 5025HereN
Hammer-type crimping tool1TE(?)HereY
Battery monitor1Victron Energy BMV-712HereN
#2/0 Lug Ring Terminal (5/16″) *3?HereN
#2/0 Lug Ring Terminal (3/8″) *3?N
#2/0 Lug Ring Terminal (1/4″) *5?N
10A LiFePO4 14.6v battery charger1Bioenno Power BPC-1510ABioenno PowerHereDedicated AC-to-DC chargerN
Tool box1Dewalt DWST24082 One Touch Tool Box, BlackHome DepotHereUsed as enclosureN
#10-24 3/4″ cap screws and nuts (x8?)1?HereN
#10-24 1″ cap screws and nuts (x6?)1?HereN
#10-24 Bonded neoprene washer (x4)3?HereN
1 1/8″ hole saw1?HereUsed for Powerwerx panel mount devicesY
Panel mount powerpole socket (x2)2Powerwerx PanelPole2PowerwerxHereN
Panel mount powerpole socket (x1)1Powerwerx PanelPole1HereN
USB A QC + USB C PD charger, panel mount2Powerwerx PanelQCUSBCHereN
Bonded 10GA stranded copper wire, 25′1Powerwerx Wire-RB-10-25HereUsed for 30A branch circuitsN
Bonded 14GA stranded copper wire, 25′1Powerwerx Wire-RB-14-25Used for 15A branch circuitN
Powerpole to “cigarette lighter” adapter1Powerwerx SOC-PPHereStored in the enclosure as an adapterN
4-Way powerpole splitter2West Mountain Radio PWRNodeHam Radio OutletHereUsed as splitters for the 2x panel mount powerpole socketsN
Panel mount rocker switch w/red LED, 15A max1Powerwerx PanelSW-RedHereN
15/30/45A red powerpole housings6Powerwerx PowerpoleCaseHereN
15/30/45A black powerpole housings6N
Powerpole retention clips6N
45A powerpole contacts22N
Powerpole crimper1Powerwerx TRICrimpHereY
F2 blade connectors, 12-10GA3???N
F2 blade connectors, 16-14GA4???N
Lug ring terminal, 12-10GA6???N
Lug ring terminal, 16-14GA2???N
7.5A ATC blade fuse *3???N
30A ATC blade fuse *5???N
Assorted ATC blade fuses6???Included in enclosureN
Packing foam **????N
Electrical tape ***1???N
1 1/4″ bolt and flange nut ****1???N
Zip ties5???N
3/16″ (?) drill bit 1???Used to drill holes in plastic fins in toolbox for zip tiesN
Electric drill1???Used w/hole saws and drill bitsY
2″ hole saw1???Used to drill a hole for the Victron BMV-712 panelY
Phillips screw driver1???Y
Metal shears1???Used to cut #2/0 welding cableY
Diagonal cutters1???Y
Socket wrench1???Y
?mm socket1???Used for shunt boltsY
?mm socket1???Used for battery terminal boltsY
?mm socket1???Used for #10 nutsY
?mm socket1???Used for DC subpanel 100A contacts
Needle nose pliers1???Used to help pull wires, tighten panel mount nutsY
Claw hammer1???Used w/ the TE hammer-type crimping toolY
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
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.

Successful Portland NET simplex exercise!

Hello radio enthusiasts, geeks, etc.! Tonight was my first exercise as a certified Portland NET (Neighborhood Emergency Team) ARO (Amature Radio Operator). We operated on simplex nets tonight throughout the city in order to practice communicating directly with each other and PBEM in the event city wide repeater networks failed during an incident.

I decided to test from my staging area tonight rather than operate from home… last time I was out I couldn’t get Pat Winlink going, and I have some new gear to test tonight: a legit collapsible table and a GoalZero LED lantern! There was supposed to be rain tonight, and the plan to cover myself and the top of the table in a tarp and work under it but alas it wasn’t necessary. The rain stayed away and I didn’t need to test my half-baked idea.

My partner and the doggo came out again and hung out with me as I operated. Most of the photos of the deployed setup and of me operating are hers taken for the blog. I should note that I don’t have her help me do any actual setup or tasks related to station operation. The idea is to make sure that I can manage all aspects of setting up, transporting, and tearing down the station without assistance.

Me sitting at a lamp-lit table with a radio on top at night, the antenna mast is in the background.
Set up at my staging area.

Setting up was pretty smooth today even in the dark. I unloaded the antenna mast and propped it up. The table was then set up and the J-pole was mounted on the non-conductive part of the mast. The second half of the 2m element was attached. After that the feedline was connected to the j-pole and the Kenwood TM-V71 was set up inside my weatherproof backpack along with the wireless access point, Winlink Pi, and 20Ah Bioenno LiFePo4 battery. With that and the ARO binder set up I powered the radio up and the resource net was just beginning.

I managed to check in just fine and the resource net controller and had an excellent signal at 5w (minimum power the radio can do). For this exercise the resource net did directed check-ins by call sign suffix. It was pretty smooth and orderly and net control did a good job. There were quite a few participants from various neighborhoods and I could hear almost every station. After all stations had checked in the subnet controller for each city region would announce their frequency and have all operators in that region move to their regional net as specified in the procedure that was sent out ahead of time. It should be mentioned that I uploaded the procedure for the exercise to the documentation server on the Raspberry Pi ahead of time as well. I was, however, missing the Multnomah County ARES frequency template. I need to make sure I have that on the document server.

Antenna mast made of a speaker stand with a wooden closet hanger deployed at the top. Open stub J-pole antenna is fixed at the top.
Antenna mast and antenna deployed

Once on the regional net we checked in using our tactical call signs. We exchanged signal reports and everyone on the net was a 5 (readability) to me which was very nice, and my signal was a 3 or above to everyone else. It looks like my staging area is pretty good in terms of connectivity to the other stations in my city region (Alameda South). Interestingly one of our operators that generally has a great signal to all stations had some trouble hearing the nearby subnet controller. I suspect there might be some multipath interference between that station and the subnet controller resulting in an unexpectedly poor signal.

Table top lit by LED lantern with a backpack containing a radio, a tablet, and zipped 3-ring binder with a partially filled form 8 and a pen on top.
Table setup with form 6 (ICS 309) in a binder, my tablet, and radio gear in a weather resistant backpack.

As we operated the radios we also filled out a form 6, or ICS 309 to track events and messages on our radios. These forms are used to document events and messages during an incident or exercise. When passing messages we fill out or voice form 8s (ICS 315), but we didn’t actually do one tonight.

Once we concluded talking on our regional nets we checked out of them using our tactical call signs, and then tuned back to the resource net and checked out there as well. It took a while to get checked out as there was a lot of doubling (more than one station transmits on the frequency at the same time interfering with other stations). It’s hard to coordinate stations by call sign suffix arriving on the resource net at random times even though the resource net controller was doing a great job.

Everything was good so far! Now it was time to attempt to send e-mail again after my last failed attempt. This time I managed to use the Winlink host and an Android tablet to send an e-mail to both OH8STN and a friend from my staging area over VHF. I had a lot of trouble sending e-mail at first. While the wifi network and applications worked just fine this time I had some challenges sending e-mail due to odd issues with the content. It seems that if the body of he e-mail or subject is too long there are protocol errors. After a few experiments I was able to finally get the messages out.

Time to break down and get some dinner! Breaking everything down was super-smooth this time around. There were no issues and everything packed away nicely! I just rolled the wagon back home and unloaded it!

Folding wagon with cloth sides loaded with equipment lit by street light. The collapsed antenna mast is  sticking from the back of the wagon.
The ham hauler loaded up on the way back home.

Lessons learned:

  • A table makes life a LOT easier when doing this sort of deployment.
  • The Goal Zero LED lantern wokred very well. The adjustable light level is very nice, and even with half the lantern on at the lowest possible power was more than enough for the vast majority of tasks I had to perform from setup to operating and filling forms to breaking down. I did increase the light level a couple times for specific tasks, but I didn’t need to keep the light level up.
  • Make sure you have all the documents you’ll need with you including frequency lists.
  • Having exercise-specific and general guides at your fingertips is a good idea. It helped in this exercise.
  • It takes 45 minutes from loading equipment to being on air for my staging area under more-or-less ideal conditions in the dark.
  • Some changes to the J-pole made it work a lot better in the field. I’ll post an entry the modifications I made.
  • My power cabling was really messy. I could do better.
  • It didn’t rain but I need to figure out a shelter that would protect the table top from wind and rain that can fit in the bag with the table.
  • The exercise seems to have gone well broadly. The check-in process was pretty efficient.
  • The check out process was a bit chaotic but maybe we could implement a system whereby net subnet controllers check into the resource net and once that happens the resource net controller adds that subnet controller’s region to a directed checkout by region. We could cycle through regions until all stations check out.

A successful-ish EMCOMM test deployment

Howdy everyone! I wanted to tell the tale of a short walk with a wagon in the rain followed by some radio tests. I decided I’d like to test moving to my staging area during a disaster response scenario. My goals were to test making contacts with my Yaesu FT3DR and do voice as well as Winlink with my Kenwood TM-V71 and portable Winlink setup. This will also be the first deployment of my Arrow OSJ 146/440 open stub dipole. This model has the split 2m element for easier transport.

Cloth-sided wagon containing various equipment and a backpack leaning against the side.
Wagon with the antenna, mast, and a couple folding chairs. Also pictured is my water resistant backpack with the radio gear and feedline.
Wing nuts installed on the antenna's pipe clamp.
Slightly modified Arrow OSJ 148/440. I replaced the stock hex nuts with 1/4″ 20 wing nuts to remove the requirement for a wrench to install the antenna in the field.

After arriving at my deployment site I removed the 1 5/8″ closet rod from the inside of the speaker stand. The long end of the closet rod stays inside the speaker stand tubing for easy transport. The stop for the closet rod is made from three eye screws that double as guy line connection points. The three eye screws are installed just above the top band of purple duct tape (reduces vibration and motion when the closet rod is installed in the end of the speaker stand).

J-pole mounted to a wooden closet rod resting against a speaker stand. The split 2m element is affixed for transport.
J-Pole with the second half of the 2m radiator threaded in place for transport.

The next step is to install the top portion of the open stub J-Pole.

J-pole mounted to a wooden closet rod resting against a speaker stand. The split 2m element is installed for transmission.
Open Stub J-pole atached to closet rod resting against the speaker stand with the 2m element fully assembled.

After the feedline is attached to the J-pole the closet rod with the antenna attached is installed in the speaker stand with the tape end of the closet rod in the top of the speaker stand. The closet rod is resting on the three eye screws that prevent it from slipping down inside the speaker stand tubing. The two telescoping sections of the speaker stand are fully extended and the locking pins are in place.

Fully extended speaker stand with closet rod and antenna attached. The wagon, my partner, and our dog are off to the side.
Antenna fully extended. Also present is my partner and our dog for moral support.
A picure of the feedline velcroed right above the tripod component of the speaker stand.
A velcro wire tie is used to anchor the feedline to the bottom of the antenna mast to prevent it from being pulled over from the top if someone trips on the cable.
Yaesu FT3DR connected to the feedline with the wagon and antenna stand in the background.
My Yaesu FT3DR attached to the feedline with a SMA to PL-259 pigtail.

I was able to make a couple contacts using the Yaesu HT at 5w and monitored APRS transmissions for a while. So far everything is good.

Hand holding microphone of Kenwood TM-V71. In the background the radio is in a dry bag and sitting on the wagon.
Kenwood TM-V71 connected to the feedline and battery in the backpack. It’s protected from rain by an Ortleib dry bag.

The Yaesu HT is stowed in its bag and the Kenwood mobile radio is connected to battery power and the feedline. It’s also protected from the rain by a 5L Ortleib dry bag. More contacts are made on 2m without issue. I was able to make contacts in Portland, OR, Aloa, OR, Washugal, WA, and Vancouver, WA at 5w. More good news!

Hand holding the Mobinlinkd TNC3 and Raspberry Pi Zero W connected to each other. Radio data connector is also set up.
Winlink host, TNC, and radio connected.

It was finally time to send and receive some e-mail! I connected the Winlink Raspbery Pi to the power supply and the Mobilinkd TNC3 to the data port on the TM-V71. I pulled my phone up, found the generated wireless network, joined it…. and nothing! It partially connects but doesn’t get an IP address. Strange, but no matter. I assigned a manual IP to my phone and tried to connect to the Pi via IP address. The connection still failed. I rebooted the Pi and tried again. The wifi network shows up, I join it, no DHCP IP address. Bummer! All my tests having either been complete or failed it was time to pack up and head home.

At home I boot the Pi and it joins the home wifi network with no issue. I SSH into the Pi and begin reviewing the configuration for Dnsmasq (DHCP/DNS server). Everything looks good and the configuration is valid. I then look at the autohotspot script. It has the default IP address that the script ships with set. Then the “aha!” moment strikes. As part of writing my Winlink host setup guide I re-ran the Autohotspot install script so I could make sure my documentation was right. The fix is now obvious: I just changed the IP address in the Autohotspot script, kicked the Winlink host off my wifi network and restarted it. I’m now able to connect, get an IP address, and connect to Winlink and the documentation server!

Lesson learned… always re-test your setup after you mess with it, and if you re-run a setup script you should verify that your setup runs properly afterward. Fortunately this was not a emergency deployment and was close to my QTH.

Other things I learned from today:

  • The wagon doesn’t negotiate steep curbs well without a bit of finesse.
  • The antenna mast should be lashed in place on the wagon during transport so it doesn’t move in the wagon.
  • The wing nuts on the J-pole can get over-tightened easily making it hard to dismantle the setup.
  • The allthread stub that connects the two parts of the 2m element on the J-pole can be unscrewed easily and lost when the element is being removed. I’ve dropped it 3 times in the first 48 hours of having the antenna. Some red or blue Loctite is probably a good idea to keep the end of the stub fixed in the removable portion of the 2m element. The red (permanent) Loctite will also keep moisture out of that joint.
  • Sometimes the telescoping tubes on the speaker stand stick.
  • I live in NW Oregon and figuring out a wind and rain shelter is probably a good idea.
  • The speaker stand is pretty stable and sturdy. It will probably work without guying in mild wind.

Portable UHF/VHF Winlink host

Howdy! I had recently posted about some Raspberry Pi based systems that can be used in the shack or in the field and those posts received a lot of questions about how they were set up. This post is the first in a series that seeks to explain the design, operation, and setup of these hosts. Some of the work I did here was inspired by Julian, OH8STN’s general off grid/grid down operating philosophy and K1CHN’s blog posts.

A Raspberry Pi W Zero in a clear acrylic case connected to a Mobilinkd TNC3 with a MicroUSB OTG cable, host end connected to the Pi's USB OTG port.
Raspberry Pi Zero W connected to Moblinkd TNC3 using a MicroUSB OTG cable.

So, what are we talking about here?

  • A Raspberry Pi Zero W / Raspbian based Pat Winlink host.
  • Designed to work with packet on UHF/VHF radios.
  • Compatible with a wide range of radios.
  • Runs on USB or 12v and has typical 45A Anderson PowerPole connectors in a “right hand red” configuration when running on 12v. This matches my off grid power setup and the ARES + RACES standards.
  • Uses a Mobilinkd TNC3 to work with a variety of UHF/VHF radios and to offload signal processing to a TNC. That means we don’t need as much processing power on the compute node. Multiple adapter cables are sold on the Mobilinkd store and you can make your own.
  • Automatically sets up and tears down the AX.25 port and connection based on the status of the TNC’s USB connection.
  • Nice, tidy web interface that can be used by any device with wifi capabilities and a fairly modern browser to send and receive e-mail.

Parts list:

  • Raspberry Pi Zero W and power supply
  • MicroSD card
  • Optional Pi Zero W case
  • Mobilinkd TNC3
  • Appropriate cable, purchased or constructed to connect from the TRRS jack on the TNC3 to your UHF/VHF radio
  • MicroUSB OTG cable for the Pi to TNC3 connection.
  • Optional USBBuddy (12v to 5v USB down converter)
  • Optionally short USB A to MicroUSB cable to cut down on voltage drop.
  • UHF/VHF radio of choice. This setup has been tested with a Baofeng UV-5R, Yaesu FT-857D, Yaesu FT-3DR, Kenwood TM-D710G, and a Kenwood TM-V71 but should work with many others. The Mobilinkd TNC3 was designed to work with a broad range of radios.

Theory of operation:

Block diagram showing control flows between and connections between the operator, radio, devices, and between the TNC and Raspberry Pi. The diagram also depicts the control flows between the TNC, ax25.service, Linux AX.25 subsystem, and Pat Winlink. Flow charts depict AX.25 service flows and a wifi flow chart describing when the system decides to host its own wifi.
Block diagram showing various system components and their interactions. Flow charts for managing the AX.25 service and self-hosted wifi.

The Pi leverages a number of smaller subsystems to provide e-mail access.

  1. Scripts and applications that provide AX.25 setup and teardown as the TNC is connected or disconnected. These scripts leverage udev and systemd to detect state changes on the TNC. While you can use Bluetooth to maintain these connections it’s easier and more simple to control connections to the TNC using its USB connection status.
  2. A set of scripts, services, and utilities that automatically provide a functional wireless network in the event the Pi is unable to connect to a known network. This includes DNS and DHCP.
  3. Pat Winlink is run as a systemd service so the operator doesn’t have to worry about starting and stopping the service. It can run in the background whether or not the TNC is connected, but it can’t send or recieve e-mail without the TNC connected.
  4. Pat Winlink is accessed via a web interface. You need a phone, tablet, or computer that can connect to the wireless network generated by the Pi, or is on the same network as the Winlink server. This allows an operator to use Winlink.

Setup process

Start by installing Raspbian on your MicroSD card and getting your Raspberry Pi up and running. The steps here should work. Make sure you give your pi a hostname like “winlink” or whatever you’d like. If you configure dnsmasq this becomes important. Once your Pi is up and running with an Internet connection we can pre-install needed utilities and software so we don’t have to do it later. We’ll also make sure dnsmasq and hostapd don’t start automatically (more on this later). These commands can be done from the Raspberry Pi’s terminal application or from an SSH session if you’ve enabled it:

sudo apt-get update -y && sudo apt-get upgrade -y
sudo apt-get install libax25 libax25-dev ax25-apps ax25-tools dnsmasq hostapd git
sudo systemctl disable hostapd
sudo systemctl disable dnsmasq

Once we have all that installed we’ll install and configure Pat Winlink. Download the latest Pat Winlink release from GitHub. You’ll want to make sure you choose the armhf (Raspberry Pi) .deb file. Make sure you note the name of the file as it will be important when running the install command. When you’re ready to upgrade Pat Winlink in the future you can download the newest version of the .deb file from the same page. Assuming you’ve downloaded the file to the Downloads folder you can run the following command to install Pat Winlink, replacing “pat_0.10.0_linux_armhf.deb” with whatever file name you downloaded:

sudo dpkg -i ~/Downloads/pat_0.10.0_linux_armhf.deb
mkdir ~/.wl2k

After we configure our AX.25 settings we can come back to configuring Pat Winlink as we’ll need some values from that setup.

Next we’ll edit /etc/ax25/axports. This file configures our AX.25 ports that get used to build connections to packet Winlink gateways. Mine looks like this. You’ll of course want to replace my callsign with yours. The port we configure below will be called wl2k. This will be needed for the Winlink configuration in a number of spots.

# /etc/ax25/axports
#
# The format of this file is:
#
# name callsign speed paclen window description
#
wl2k K7JLX 9600 255 7 Winlink (9600)

In the next step we’ll create three files – a script that manages AX.25 port connections, a systemd service that manages the AX.25 port, and finally a udev rule that starts and stops that systemd service when the Mobilinkd TNC3 shows up as a USB serial device or is disconnected.

First, let’s install ax25-up, a script in the Winlink project that manages AX.25 connections. Our systemd unit depends on it. The commands in this step come from here, but are slightly modified to put the script in a different location on the Pi.

bin="/usr/sbin/ax25-up"
sudo curl -o $bin https://raw.githubusercontent.com/la5nta/pat/master/share/bin/axup
sudo chmod +x $bin

Next we’ll add the udev rules that work with systemd to start and stop the service. Add the following contents to /etc/udev/rules.d/99-hamradio.rules:

# Mobilinkd TNC3
ACTION=="add", ATTRS{idVendor}=="0483", ATTRS{idProduct}=="5740", ATTRS{manufacturer}=="Mobilinkd LLC", SYMLINK+="ttyTNC", TAG+="systemd", ENV{SYSTEMD_WANTS}="ax25.service"
ACTION=="remove", SUBSYSTEM=="usb", ENV{PRODUCT}=="483/5740/200", TAG+="systemd"

We’ll now create our systemd unit file which should be: /usr/lib/systemd/system/ax25.service Note the ExecStart command where we use our wl2k port, and /dev/ttyTNC as created by our udev rules. That device is created in the event we attach another USB serial device to create a predictable name no matter what the proper udev name of the device is.

[Unit]
Description=AX.25 KISS interface
Before=network.target
Wants=network.target
BindsTo=dev-ttyTNC.device
After=dev-ttyTNC.device
[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/usr/sbin/ax25-up /dev/ttyTNC wl2k 9600
ExecStop=killall kissattach
KillMode=none
[Install]
WantedBy=multi-user.target

Configuring and setting Pat Winlink up as a service

First we’re going to put in a configuration for Pat Winlink. We’ll do that by editing ~/.wl2k/config.json. You’ll want to replace the values I have in my configuration with your own. I’m connecting to a station called W7LT-10 most of the time. You’ll also want to remove your password until you’ve set one. Follow these instructions for that process. Replace your callsign and grid square locator with your own. You may also want to add your own connect_alias entries. These can be various Winlink stations you want to “bookmark” for quick connection. I’ve added a number of them for use while I’m out camping. In that list you might have noticed the one beginning with “!W7LT-10”. Since I use that one most commonly I added an ! to the front of the name to keep it at the very top of the list when it’s alphabetized by the Pat Winlink application. The http_addr directive tells Pat Winlink to listen on any address on port 8080. This will be important when constructing the URL to access Pat Winlink with. You may also notice that I’ve configured this to listen on ax.25 and telnet. This allows the Pat Winlink application to listen in peer-to-peer mode for incoming connections. You don’t have to switch between peer-to-peer and CMS mode manually like you would using Winlink Express. You may want to assign a new telnet password if you want to keep the listen entry for telnet.

{
  "mycall": "K7JLX",
  "secure_login_password": "VerySecret",
  "http_addr": "0.0.0.0:8080",
  "listen": ["ax25", "telnet"],
  "locator": "CN85qm",
  "motd": ["K7JLX Pat Winlink stn"],
  "connect_aliases": {
    "!W7LT-10, 144.910MHz, PDX": "ax25:///W7LT-10?freq=144910",
    "K7HWY-11, 145.030MHz, La Pine, OR": "ax25:///K7HWY-11?freq=145030",
    "KB7EOC-10, 144.950, Tillamook, OR": "ax25:///KB7EOC-10?freq=144950",
    "KG7AV-10, 145.030MHz, Bend, OR": "ax25:///KG7AV-10?freq=145030",
    "W7EUG-10, 145.030MHz, Eugene, OR": "ax25:///W7EUG-10?freq=145030",
    "W7GC-11, 144.950, Hebo Lake, OR": "ax25:///W7GC-11?freq=144950",
    "WC7EOC-10, 144.980MHz, Hillboro, OR": "ax25:///WC7EOC-10?freq=144980",
    "WW7CH-10, 145.050MHz, Eatonville, WA": "ax25://WW7CH-10?freq=145050",
    "N7GWK-10, 145.630MHz, Centrailia, WA": "ax25://N7GWK-10?freq=145630",
    "N7DEM-10, 144.920MHz, Longview, WA": "ax25://N7DEM-10?freq=144920",
    "W7BO-10, 144.920MHz, Woodland, WA": "ax25://W7BO-10?freq=144920",
    "KA7CTT-10, 144.920MHz, Vancouver, WA": "ax25://KA7CTT-10?freq=144920",
    "W6TQF-10, 145.055MHz, Underwood, WA": "ax25://W6TQF-10?freq=145055",
    "N7YRC-10, 144.930MHz, Yakima, WA": "ax25://N7YRC-10?freq=144930"
  },
  "ax25": {
    "port": "wl2k"
  },
  "telnet": {
    "listen_addr": ":8774",
    "password": "AlsoVerySecret" 
  }
}

Now that we have a solid initial configuration let’s set Pat Winlink up as a service that starts automatically when the Pi boots. The first step is creating a new systemd unit at /lib/systemd/system/pat.service which will run as the standard pi user that ships with Raspbian. The contents of that systemd service are as follows:

[Unit]
Description=Pat Winlink HTTP server
After=ax25.service
[Service]
Type=simple
ExecStart=/usr/bin/pat http
User=pi
Group=pi
[Install]
WantedBy=default.target

Now we start and enable the service by running some commands in the terminal. The last command should show Pat up and running with a green “active” status. You can press “q” to quit the status display.

sudo systemctl enable pat
sudo systemctl start pat
sudo systemctl status pat

To test all the work we’ve done thus far reboot your Raspberry Pi using the GUI or by issuing the following command in the terminal:

sudo shutdown -r now

Once your Pi is back up and you’re logged back in as the pi user we’ll connect the Mobilinkd TNC3 to the Pi using the MicroUSB OTG cable. The host side connects to the Pi’s USB port, not the power port. After plugging the cable in press the connect button on the Mobilind TNC3. You’ll see a yellow flash on the TNC’s status LED. This momentary button press should trigger the ax.25 systemd service to start. We can check on that by running the following command:

sudo systemctl status ax25

If you see that the service is active and green you’re good to go on the base Winlink functionality. The only thing left to do is connect to it. Use your browser connect access Winlink with a URL derived from this template: http://<your winlink hostname or IP>:8080

If you want an automatic hotspot proceed to the next step.

Automatic hotspot

For this part of the guide just follow the steps that Raspberry Connect lists. You can modify their scripts to create IP addresses and wireless network names/passwords as needed. You can modify the /usr/bin/autohotspotN script and set the IP address there. In the createAdhocNetwork() function modify the ip a add line with the desired IP and subnet mask.

After the scripts scripts have been run and things have been configured you can optionally set up DNS records in dnsmasq. My configuration looks like this but yours will certainly vary. The static IP addresses and DNS records help Android devices or other systems that don’t work well with MDNS find your winlink service. You can use any network you want. The dhcp-host line for winlink.local is commented out because the host we’re running won’t get a DHCP address from itself. The additional entries help other Raspberry Pis or other devices get static IPs and allow them to be found by hosts. In this way we can make sure any devices that connect to your network that offer services show up. Make sure the ‘address’ line matches the hostname of your pi, and that the IP matches the one you set after the RaspberyConnect’s script run in the previous steps.

interface=wlan0
no-resolv
bind-interfaces
dhcp-range=192.168.255.20,192.168.255.250,4h
address=/ft857d.local/192.168.255.1
dhcp-host=dc:a6:32:11:11:11,192.168.255.1
address=/winlink.local/192.168.255.2
#dhcp-host=b8:27:eb:22:22:22,192.168.255.2
address=/tx500.local/192.168.255.3
dhcp-host=dc:a6:32:33:33:33,192.168.255.3

Multicast DNS (MDNS)

To help devices that support MDNS automatically discover the winlink service we can add a configuration file to Avahi. To do that create a file at /etc/avahi/services/winlink.service:

<?xml version="1.0" standalone='no'?>
<!DOCTYPE service-group SYSTEM "avahi-service.dtd">
<service-group>
  <name replace-wildcards="yes">Winlink on %h</name>
  <service>
    <type>_http._tcp</type>
    <port>8080</port>
  </service>
</service-group>

Now restart Avahi using the following commands:

sudo systemctl restart avahi

At this point if your pi can’t reach a known wifi network it should start its own. Make sure you test it before you need it to work in a real-life situation.

As a bonus you can create a document server on the Pi to make sure you have information, forms, manuals, etc. when you need them in the field.

Updates to this blog entry:

4 Sep, 2021 – The Pat Winlink configuration section was updated to reflect changes I’ve made since the original draft of this entry.

A random field day (Jan 16, 2021)

I had the opportunity to spend a few hours in the Oregon countryside while my partner had a meeting. Naturally I decided to do deploy my new radio, the Lab599 Discovery TX-500 along with my second purpose-built digital comms Raspberry Pi. The other is used with my Yaesu FT-857D.

Picture of radio equipment in the back of a Prius along with a folding chair facing the hatch back.

I began by setting my rig up in the trunk of my car. Since I wanted to at least simulate running off grid on battery I didn’t connect my radio to the car and opted to use my 40Ah Bioenno LiFePO4 battery. I had intended to bring my smaller 12Ah Bioenno LiFePO4 battery which was actually purchased for the TX-500 kit, but I had spaced it and left it on the charger. Despite the cloudy weather that is typical of Oregon this time of year I also brought my GoalZero Nomad 20 to see if I could extend my runtime even if slightly and to give it a good test. Every little bit of extra juice helps, but I only used 1.8Ah of battery the entire 5.5hr deployment! The solar panel did provide an additional 0.8Ah which is 44% of what the battery provided.

Folding solar panel placed on top of the car roof with cable running to hatch back.

Solar panel on the car and facing south

Buddipole power mini lashed to a 40ah LiFePo4 battery
Buddipole Power Mini and 40Ah Bioenno LiFePo4 battery.

The first antenna I deployed and ran was my Superantenna kit, but instead of using the titanium whip supplied with the kit I added the Chameleon Mil Whip 2.0 to get more efficiency and significantly wider SWR bandwidth. I tuned the antenna up for 20m using my NanoVNA and ran JS8Call on the TX-500’s dedicated Raspberry Pi… using my tablet as a keyboard and screen over VNC. I had a number of successful contacts from the Southwest to AK and managed to relay a text message to a friend in NM via an operator in-state running 9w!

Superantenna deployed on a tripod topped with a Chameleon Mil Whip 2.0.
Superantenna w/ tripod and Chameleon Mil Whip 2.0

I did try to make some SSB phone contacts but there was a contest going so I didn’t really get too far. As the sun started going down I noticed the 20m band was starting to close, so I tuned to 40m and the contest was still going on so I wasn’t able to make any contacts. It can be difficult to raise anyone during a contest because a lot of folks are talking and running high power so it’s very easy to be drowned out.

In general I also like to try more than one antenna or antenna configuration per deployment so I set up my Chameleon EMCOMM Portable III in an inverted “V” configuration with the center point hung using an arborists’s weight and some paracord in a tree. I was able to make some JS8Call contacts and was able to hear a lot of distant operators. Again, I was unable to make a contact using SSB phone despite the fact that the tuned inverted V configuration should technically be more efficient than a loaded vertical. I’ll need to do another test on another day.