I recently went into a rabbit hole of finding the best battery pack for an electronic candle that will be installed in a large Christmas Wreath. The pair of alkaline batteries holds the charge for 2-3 days; my goal is 7 more. Ideally — 30. The light draws 39mAh:

LiFePo4 is convenient for this setup, because it provides:

1. 3.2V – the voltage the candle accepts (normally 2x1.5V AA).
2. It fails safely. I.e. the wreath won’t catch fire if something goes wrong.

The battery I bought first holds 6Ah — rated maximum of 6.5 days. However, once connected to the candle, it held the candle lit for only 30 hours, which brings it to ~1-2.2Ah, which is about 5 times less than the rated capacity!

So I went ahead and bought a Gyrfalcon s8000 battery tester, so I can test whatever batteries I purchase before installing them to the candles.

While on it, I purchased a few 15Ah batteries (32140FSBAK). A single battery should provide 16 days of uninterrupted light. If we wire 2 of those in parallel, that would provide the advent month, and then some!

Testing 32140 with Gyrfalcon s8000

s8000 is restricted in what batteries it can comfortably test:

1. max form factor: 32700 (32 x 700 mm)
2. max charge capacity: 9999 mAh.

However, the larger 32140 is different in both dimensions:

1. form factor: 32 x 140 mm.
2. capacity: 15000 Ah.

My son used Lego, some wires and a few clips to solder a dummy battery that will accept any any form factor to the s8000:

For issue (2), I asked Gyrfalcon what to do, and they bumped the max charge capacity to 30000mAh in their next firmware update. It took 4 days from the initial “cold” email (“what do I do?”) to an updated firmware in my inbox.

Testing commences! I will write a separate post with results from those batteries.