Building Better Battery Boxes

The need for emergency power is something every ham operator should take into consideration. Over the last few years, batteries have become more affordable, longer-lasting, lighter weight, or a combination of these qualities. The latest battery craze is for LiFePO4 (Lithium Iron Phosphate) batteries, a growing favorite among many makers and tinkerers for their light weight, long charge times, lower cost, and tolerances for hot and cold ambient temperatures. 

LiFePO4 batteries have also become a solid item in many hams' shacks for emergency power and can be used in golf carts, trolling motors, and even some Tesla automobiles will be investing in these types of batteries for lower costs to construct and better life-cycles.

The reasonable cost and the (much!) lighter weight are reasons I decided to invest in an emergency power source.

I had some prerequisites for needing such a power source:

• Light weight
• Portable
• Multiple means of providing power
• Anderson power poles
• USB
• AC power
• Car adapter
• Able to be recharged via solar or commercial power
• Easy to maintain and use

I searched on the internet for a compatible battery box to hold the battery and discovered the Hiximi battery box that looked to be the best fit. It had a built-in voltmeter with a switch that controlled two car adapters and 2 USB outlets. 

My next item was the star of the attraction: the battery! Again the LiFePO4 batteries were highly recommended from several hams for their tolerances to temperatures and their weight, along with the ability to maintain a steady power level during heavy use and drainage. I attended a POTA-Palooza event at Big Ridge State Park in the fall of 2024 and got to see several set-ups first hand. Some of the batteries were LiFePO4 batteries and I asked several of their owners how they functioned, were they happy with these batteries, etc. All gave a thumbs up to these batteries. One was
an ECO-WORTHY brand which was HIGHLY recommended and when I got home I found one on Amazon. I decided to go with the 50Ah battery, because, while I did not think I would ever need all of that potential energy, it still would be nice to have, and use it to power my HF rig over several hours, such as when operating the Tennessee QSO party.

As I waited for the battery, I looked over images of other battery boxes and contemplated what other items I would need. I would need a way to charge the battery, and a way to invert the DC to an AC output to allow household items to be plugged in. I went back to Amazon and saw that ECO-WORTHY also had a charger. It was compatible with several battery types including LiFePO4 batteries. This is something to consider when getting a charger, that it specifically be compatible to the battery you purchase. 

While on a trip to Walmart, I stopped in the automotive department to browse the power inverters, and found an Everstart 750W version. While this version I linked is slightly different cosmetically, itis still the same as the one I obtained. Along with a high wattage and two AC plugs, it also has 2 additional USB ports that can be used along with the 2 onboard the battery box. 

As I waited for most of the parts to arrive, I also considered the need for solar power to recharge the battery. I found solar panels were getting to be fairly affordable as well, so I looked on Amazon (again) and found a 100W foldable solar panel that best fit my requirements for portability, compactibility, and a built-in charger controller that allowed for the panels to charge the battery without the possibility of chargeback to the panels if the battery is fully charged. It uses anderson power poles, so I ended up going to a local hamfest and purchased a power pole socket to connect to the battery. 

Once everything was ready to set up, it took about 2 hours to set everything up the way I wanted. Putting in the battery was the easy part. It came with foam padding from the delivery, so I just moved it all into the battery box and it fit perfectly. The padding keeps the battery from jostling around in a loose box. 

The ECO-WORTHY battery came with a socket to use for screwing down the wires to the terminals on the battery. I taped it to the battery after use to keep it handy in case it's needed. While showing it off to a battery box expert (Bill, KK4PAL) he noted that the socket would perfectly line up with the terminals and possibly cause a short if the stars aligned. I agreed and will probably cover the ends in plasti-dip or something similar to insulate it. For now I used electrical tape around the ends to prevent the possibility of a short.

After sorting out the battery install, I needed to install the inverter and charger/controller. I installed the controller on the outside chassis of the box using the supplied screws and liquid nails for ensuring a firm seal. The internal padding also keeps the sharp ends of the screws from scraping and possibly puncturing the battery.

The charger SHOULD ALWAYS BE OUTSIDE OF THE BATTERY BOX due to the high heat it produces and that heat could shorten the life of any battery you use. If I am being transparent, I initially wanted to put it in the box to save space, but fortunately it wouldn't fit and Bill advised it is always good to keep the charger out of the box so that it doesn't overheat while charging, which could cause thermal breakdown issues with the battery, shortening its lifespan.

Next was the inverter. I had to install on the outside as well since it needed the AC plugs on the outside. Because it has a cooling fan, it is best to keep it outside the battery box to allow the cooling fan to do its job for keeping the inverter cool when higher current-drawing products are plugged in (like fans, TVs, and lamps). I also added ferrite cores to all the wires of all devices to help minimize any potential electromagnetic interference or HF interference.

With the box, the 50Ah battery, charger/controller, and inverter, the box weighs in at 21lbs. With a smaller battery, it will obviously weigh less, but 21lbs with a LiFePO4 battery is MUCH lighter than trying to use a Lithium-Ion or a lead-acid battery. And again, it's better to have more than enough power than not enough.

After setting up the box with all of this, I took it for a few test runs, setting up my go kit, running a few devices on it (floor lamp, chargers, camera, etc) and it's been almost flawless. But I needed to get solar capability set up, so I got my 30a Anderson power pole mount and proceeded to drill a hole in the opposite side to where the USB and car chargers were. It took less than 15 minutes to set up the port and within 30 minutes of that, I had the solar setup completed. 

The next sunny day I took the panels out and set them up and they worked perfectly to keep the battery box charged while I tested HF with my go-kit. 

The first true test came at last month's Tennessee QSO Party, where I plugged my kit into it and ran the radio for 11 hours. It kept going throughout the entire event and never went below 13.1V.

I took it to the Clinton Amateur Radio Society meeting and Bill KK4PAL was giving a talk on battery boxes. As mentioned earlier, he's a battery box expert, having built several over the last few months. He looked over my build and was impressed by the design, and attendees asked many questions about my battery box and I had a few handouts with all the details. A PDF of everything in my battery box is here. A Youtube video of Bill's presentation is below:

I took it to the East Tennessee Hamfest and was planning to discuss SKYWARN, and I brought my battery box to power the laptop. More people were interested in the battery box than they were about SKYWARN (maybe because I preach it every chance I get). And recently I took it to do a POTA operation and again, it did everything it was designed to do. 

I even used it recently to help keep my mother's portable oxygen concentrator running during a power outage at our home. With her being on oxygen now, the box has become a critical component in keeping her assured we can keep her oxygen supply going for as long as needed. Her concentrator will last about 4 hours on a charge. With my battery box, we may have at least 24 hours is my guess.

Here are my key takeaways with the battery box:

1. I enjoyed building it, but Bill's battery boxes look more robust and I plan to set up a portable digipeater, so Bill's setup will be more conducive to my needs for putting it on the air. I will be reaching out to him soon to put one together for me as I already have another battery and charger ready to go.
2. I will probably install another set of power poles to have power OUT from the battery to power compatible devices. I could go ahead and use the solar input but I want to keep them separate and use the onboard switch to also control the power pole port.
3. This was an expensive box to build overall, but definitely more affordable than one I thought to build just a few short years ago. 
4. Now with my mother on oxygen, this has become an even more valuable tool to have not just for radio.