More Gamasonic Testing

I built a 4-cell solar battery from Gamasonic flashights. This produced a solid 8.4V when fully charged. That's too much for an Arduino to measure directly, so I bought a Sparkfun ACS37800 power meter.

I wired the meter up directly between the 4-cell battery and a load made from 3 white LEDs soldered together end to end, like this:

And of course changed the source to accomodate.

Here's what it looked like in Real Life:

Alas, the ACS37800 lacks accuracy at the low current levels I was measuring, so I am unsure if these results have any much validity. But here is the data anyways.

Next, I tried using just two cells wired in parallel, for a total voltage of only 4.2 volts but enhanced ampere hours. With this size, I could use the same setup I did for a single cell, so that's what I did. That gave me this file. The output voltage barely budged over sixteen hours of testing, so this might be the sweet spot for a garden sensor. I also observed some interesting trends. The output seemed to cycle over about a minute, gradually rising and then abruptly falling:

I am not sure why this was happening, but I suspect it is a property of the LED rather than the battery.

-- CharlesShapiro - 10 Mar 2026