Building a LiFePO4 Field Battery for POTA — My 32Ah Ammo Can Build
- 6 min reading time
One of the most satisfying builds you can do for POTA is your own field power unit. Commercial options exist but they're expensive, often undersized, and built for general consumers — not ham radio operators who need Anderson Powerpoles, a real voltmeter, and enough capacity to run multiple activations back to back. Here's my complete 32Ah LiFePO4 ammo can build from start to finish.
Why LiFePO4?
LiFePO4 (lithium iron phosphate) is the chemistry of choice for ham radio field power for good reason. It's lighter than sealed lead acid, holds voltage flatter across its discharge curve, handles more charge cycles, and is significantly safer than other lithium chemistries. For a portable station that lives in a backpack and gets used in Florida heat, there was no other choice.
The Enclosure — Harbor Freight .50 Caliber Ammo Can
The foundation of the build is a Harbor Freight .50 caliber plastic ammo can. Rugged, weatherproof, and sized just right for four 8Ah cells with room for wiring. Plastic was a deliberate choice over metal — no risk of shorts against the enclosure walls and lighter to carry. At a few dollars it's one of the best value enclosures you'll find for a field power build.
[Link: Harbor Freight .50 Cal Ammo Can]
The Cells — 4x LiFePO4 8Ah 12V
The heart of the build is four LiFePO4 12V 8Ah cells wired in parallel, giving a total capacity of 32Ah at 12V. Wiring in parallel keeps the voltage at 12V while multiplying the capacity — exactly what you want for a field radio power supply. These cells fit cleanly inside the ammo can with enough room to route wiring without cramming.
[Link: LiFePO4 12V 8Ah cells on Amazon]
The Fusing — 10 AWG Inline Fuse Holders
Safety first. I run a 10 AWG inline fuse holder on both the positive and negative sides of the parallel cell bank before anything connects to the panel. This protects the cells and the wiring in the event of a short or overload. Do not skip fusing on a lithium build — it is not optional.
[Link: 10 AWG Inline Fuse Holder on Amazon]
The Panel — 4-in-1 Power Panel
This is the part that makes the whole build clean and simple. Instead of sourcing and mounting individual components I used a 4-in-1 panel that combines everything into one unit:
- Digital voltmeter with voltage and percentage indicator so you always know your state of charge
- Two Anderson Powerpole connectors for direct radio connection
- USB-C PD fast charging port
- QC 3.0 USB-A fast charging port
- 12V cigarette lighter socket for accessories
- Master on/off switch
One panel, one cutout, everything labeled and clean. It's a genuinely well-designed piece of kit for a field power build.
[Link: 4-in-1 Power Panel on Amazon]
The Wiring
All cells are wired in parallel using 10 AWG wire — positive to positive, negative to negative across all four cells. Both the positive and negative runs go through their own inline fuse holder before reaching the panel. Everything is terminated with ring terminals and the connections are tight and clean. 10 AWG is appropriate for the current demands of a QRP field station and gives plenty of headroom.
The Finished Build
The completed battery box delivers 32Ah at 12V — enough to run the Xiegu X6200 through multiple full activations without worrying about running dry. The voltmeter gives a real-time state of charge readout at a glance, the Anderson Powerpoles connect directly to the radio, and the USB ports keep the tablet and phone topped off all day. The lid closes and latches securely and the whole unit is rugged enough to toss in the back of a truck.
Total build cost is significantly less than a comparable commercial unit and you get exactly the capacity and connections you need.
Parts List
| Part | Link |
|---|---|
| Harbor Freight .50 Cal Ammo Can | Link |
| LiFePO4 12V 8Ah cells (x4) | Link |
| 4-in-1 Power Panel | Link |
| 10 AWG Inline Fuse Holder (x2) | Link |
| 10 AWG wire, ring terminals, heat shrink | Link |
Final Thoughts
Home-brewing your own field power is one of the most rewarding builds in ham radio. You end up with exactly what you need, built the way you want it, at a fraction of the cost of commercial alternatives. If you have any questions about the build drop them in the comments — I'm happy to help you plan your own.
73 de W4GGJ — see you in the logs.
