In testing, I found that the charger will over discharge batteries1. Deep discharge or over-discharge can happen during low-light conditions when the charger is unable to charge but the battery is still in use. For example, if you have a microcontroller deployed to the field and fully dependent on solar power for battery recharge and you have a couple days of cloudy weather, out of the box the solar charger from Adafruit will allow the microcontroller to fully deplete the battery, which can cause an internal short-circuit of the battery. Other of Adafruit’s chargers for Lithium batteries won’t even charge a battery that is below 3.0v, presumably because it’s very easy to overheat one that has been deep or over discharged.
To address this, I am looking at the LiPo Fuel Gauge from Sparkfun. So far my initial testing of it hasn’t been positive in that it seems to be under-reporting available capacity. I need to figure out if I’m doing something wrong before making a clear judgement of that device.
1. https://forums.adafruit.com/viewtopic.php?f=8&t=58429#p295564 ↩