Once again, I put out the question about another battery build. The votes point to a smaller, lighter pack. Well, on October 04 2017, parts for the second build in the Portable LiFePO4 Power for ham radio series started arriving.. This time we are building an ultra-lightweight 5Ah 4S2P LiFePO4 pack, based on A123 ANR26650 cells. This post will serve as the introduction and episode notes.
Who would want to build this?
This one will be especially interesting for QRP hikers, SOTA ops, RaDAR Challenge ops, or any operator needing a lightweight pack, which doesn’t take a whole lot of space in a rucksack. Think about the qrp camper/hiker, or a casual operator in the field operating a few hours at a time. An operator who needs renewable off grid power, without carrying something which becomes a boat anchor when its depleted. Like all of the packs we’ve built previously this one can be simultaneously charged and recharged in the field using our solar panels and charge controllers. For me any time I can deploy the PowerFilm is going to be a good day.
Here’s an example of a planned trip. In the next year or two I hope to be hiking the Camino de Santiago in Northern Spain. Definitely I want to take amateur radio along on the hike. I expect the hike to take 30 – 40 days to complete. During off days, I’d like to use a rig like my 817, kx2, or mcHF while camping. Since I’m using a hiking trailer, I’ll have a solar panel mounted to the trailer charging up this small battery pack as I hike. This gives me off grid and renewable portable power in the field, topped up each day without the need to recharge using mains power. The benefits are obvious. replenish what you have in the field, no need for the boat anchor.
Parts for this build are:
- 8x A123 ANR26650M (I’m using B-grade cells)
- 8x 2×1 26650 snap together battery holders
- 4s BMS board 10-40A
- Solar charge controller
- Small enclosure or pouch
- Powerpole connectors
- Small DC power distribution box
- Wires, heatshrink, …
The battery pack will be in a 4S2P configuration. that means half the capacity of our previous battery pack, but also half the size and less hassle going through airports. Like the 10 amp hour version, we’ll be able to use the Genasun GV-5 mppt charge controller, or whatever charge controller you want to use, provided it’s compatible with 4S lithium iron phosphate pack 14.2-14.6v cccv.
I’m planning on spot welding the connections of this battery pack. I may want to do a short video on building a DIY spot welder, to augment the video. Let me know if that would be interesting in the comments. If I can’t get the parts up here fast enough I’ll just go ahead and solder the joints.
Previous episodes in this series:
- Solar powered gokit: https://youtu.be/1_-Q0ORT93M
- 10Ah Battery Pack LiFePO4: https://youtu.be/SJGKuriGRok
- PowerFilm F15-1200 Portable Solar Power for Ham Radio https://youtu.be/AEXP2mhcN_w
- QRP Battery pack Li-Ion: https://youtu.be/Fdjn1nSrkkY