When I was looking for a portable 12v DC power solution, I started with a West Mountain Radio Epic PWRGate as a controller/charger for the 12v Deep Cycle/Marine/RV battery from my travel trailer. Since I bring the battery from the trailer inside during the winter, I figured that I might as well make use of it with the radio, and keep it charged.
The West Mountain Radio Epic PWRGate is a slick device. It has inputs for power supply and solar panels, connection to/from the battery, and the output or load. It will act as a battery charge controller, and can be set for the battery chemistry — sealed lead acid/gel, AGM, or LiFePO4. It will also act as an Uninterruptible Power Supply (UPS) that will automatically switch from the input power to running the load from the battery.
I used the RV battery for Winter Field Day in January 2020, and it worked well to power the radio, but it is HEAVY! The RV battery weighs about 53 lbs. I had decided that for ARRL Field Day in June 2020 I wanted to have a LiFePO4 battery, which are much smaller and lighter, but can offer similar or better capacity/run-time. By comparison, the 30Ah LiFePO4 battery that I selected only weighs 7.6 lbs.
Researching some of the run-time calculators showed that a 30A/hr LiFePO4 should power my Yaesu FT-991A for an estimated six hours, which I think is a reasonable compromise between run-time and cost. This is actually double the run-time of the 79Ah Deep Cycle/Marine/RV battery from my trailer, which would have cost about the same to replace. I decided to go with the Bioenno LPF-1230A, as they are high quality, and engineered with a built-in controller to prevent over-charging or under-voltage conditions which might damage the battery. They are not inexpensive, but I wanted a reliable solution.
To protect the battery, and provide an array of connections, I also thought that I should get a battery box. I had looked at the DC-to-Go options from West Mountain Radio, but was concerned that the controller and distribution block are mounted to the outside of the battery box, where they are not protected. I also already had the Epic PWRGate, so I didn’t need to buy another for the battery box. Building a custom box without the PWRGate would have cost just as much. Instead, I decided on the Powerwerx MEGAbox, which is a heavy-duty plastic battery box, with a set of binding posts, four sets of Anderson PowerPole connectors, a “cigarette lighter” jack, a pair of USB type A jacks, a high-power USB and USB-C jack. The USB-C jack also has a volt meter built-in. The accessory ports are protected by a 15A switchable circuit breaker. Since all of the connectors are on the top, with rubber covers, everything is fairly well protected from the elements when working outdoors in the field. The MEGAbox is large enough that there is plenty of extra room for a small power supply, cables, handheld charger, etc.
This setup worked great for Field Day this year, as I didn’t expect to have a power supply connected, but would have to charge the battery from a generator offline. For use at home, and for ARES emergency communications activations, I wanted to have the power go through the Epic PWRGate to keep the battery charged when there is power, but to keep the equipment up and running if the power goes out. Initially, I’ve used some 1/2″ Velcro dots to anchor the Epic PWRGate to the top of my MFJ-4230MVP switching power supply. I run a 1′ cable from the power supply to the input, connect the radio to the load, and have a 10′ PowerPole extension cable that goes to one of the PowerPole jacks on the MEGAbox. This only gives me one output jack that is controlled by the Epic PWRGate, although there are other PowerPole ports on the MEGAbox that could be used for other devices directly from the battery.
I decided that a “cleaner” way to go would be to mount the Epic PWRGate inside of the MEGAbox, and put it in between the 50A PowerPoles from the battery to the wiring harness in the box. While I could have cut off the 50A connectors and replaced them with 45A PowerPoles, I decided to keep everything “stock” so I picked up a pair of PP50 to PP45 pigtails from Powerwerx for about $13 each. One connects to the Epic PWRGate for the battery, and the other to wiring harness for the load. This leaves the solar panel input and the power supply input to be connected. Powerwerx sells the dual PowerPole panel-mount jack assemblies for about $20. I bought one of those, along with a 1-1/8″ hole saw, as well as some 10AWG zip cord and a package of PP45 connectors. This gave me all of the materials needed.
I measured the location of the original panel mount jack on the top of the MEGAbox, and marked the location on the opposite side of the handle to keep it symmetrical. I used the 1-1/8″ hole saw (the only size that I didn’t already have…) from Powerwerx and easily drilled through the top of the box. It was straight-forward to install the panel mount jack with cover. There are a pair of PowerPole shells built into the panel jack. Powerwerx supplied a set of 30A terminals, but I used the 45A terminals that I purchased with the shells. I measured out how much wire was needed to go from the panel jack to the connectors on the Epic PWRGate when the lid was opened, and cut the wires to length. I crimped on the terminals, and inserted one end into the back of the panel jack, and put a shell on the other end to connect to the Epic PWRGate.
Since I already had 1/2″ Velcro dots on the bottom of the Epic PWRGate where I attach it to the top of my power supply, I placed another set of Velcro dots on the existing feet and positioned it in the center of the top of the Bioenno BLF-1230A, which was already in place inside the MEGAbox. The Velcro seems to hold it in place well enough, but it can easily be removed when needed. I connected the wires from the newly installed input jacks to their respective Solar and Input connectors on the Epic PWRGate, and connected the pigtails to the battery and the harness inside of the MEGAbox.
Now the Epic PWRGate is “self-contained” within the battery box. If I have a power supply available, I can connect it to the exterior panel mount jack. I don’t have a solar panel yet, but when I get one, I’ll be able to plug that into the input jack as well.
Fellow ARESDEC member W0RDR liked the Powerwerx MEGAbox when I showed it at a meeting this fall, as well as the idea of integrating with the Epic PWRGate, so he’s already built one similar to this one. His concern was that the PWRGate draws some power from the battery when there is no supply, so he also added a battery cutoff switch in between the binding posts and PowerPole output panel jacks.
Solar Panel Update
Last year, in May 2022, I purchased a solar panel before field day. Based on a recommendation from W0RDR, I bought a Dokio 300w folding solar panel from Amazon. It puts out up to 18v DC at up to 16a, and was still able to produce usable power at Field Day last year even when it was overcast and sprinkling. While this is a larger panel than one would want to take on a hike, it folds up relatively small, and is easy to fit with other gear in a vehicle for field day, camping, etc.
The Dokio panel is wired with an SAE connector, and comes with a cable to connect to a 20a charge controller which has a pair of USB ports, and XT60 jacks to connect to a battery with a pair of clips, and a cable with a variety of adapters to connect to power banks or other devices.
To connect to my battery box, I bought a 12′ SAE extension cable with a “gender bender.” I cut off one end and crimped on a pair of Anderson PowerPole connectors. This lets me plug into the West Mountain Radio Epic PWRgate, which acts as a charge controller between the solar panel and battery. The “gender bender” lets you reverse the polarity of the SAE connectors when connecting the extension cable.
Part of the challenge of using solar panels is keeping them properly oriented toward the sun, at the correct angle, to maximize efficiency. Since the position of the sun relative to the earth is constantly changing, this requires periodically repositioning the solar panel. I built a stand for my panels that is basically an adjustable saw horse, made from two 8′ 1″x2″ pine boards, a couple of small hinges, four carriage bolts and wing nuts to attach the legs to the rail, and a few feet of paracord.
I cut the front legs a few inches longer than the back legs, to allow space to attach them to the top rail with 1/4″ carriage bolts and wing nuts, with a flat washer under the wing nuts. I aligned the legs at the bottom, and attached together with a small hinge. The legs are attached to the top rail, spaced apart to align with the fold for the two outer panels to provide support. I ran a couple of short lengths of the paracord between the front leg and back leg on each side, so that I can adjust the angle of the legs by tying a knot in the paracord to hold it in position. I also stretched a longer length of paracord between the two front legs, straight across the bottom, and making an “X” across the middle, to help support the flexible solar panels and keep them from sagging. Once the stand is stood up, the solar panel is attached with a set of plastic spring clamps that I found on Amazon. The design below shows the dimensions that fit my Dokio 300w panel.
I have also picked up a couple of power meters to monitor how much power the solar panel is producing, and how much power I’m using. They come with bare wire leads, which were tinned. I cut off the tinned ends and stripped a little insulation to expose bare wire to crimp a set of Anderson PowerPoles on each end. This lets me put them inline with the solar panel, battery, or radio to measure voltage, current, and power consumption in watt-hours or amp-hours.
