I would like to check the health of some large capacity (circa 10,000mAh) 5V USB battery packs that have been sitting around for a long time. There is another post "How to monitor voltage and charge status in USB battery pack" but this didn't say when to discard a pack.
How come they're 5V when LIPOs are 3.7V? i.e. is it 2S with buck converter or 1S with boost converter?
I looked at a Skyrc S60 balance charger which can measure resistance and other things on drone Lipo batteries but these seem to have balance connector leads. So I can't see how to connect a 5V retail battery pack with female micro-USB charging socket and normal female USB supply sockets.
I think the balance charger is for drone batteries and so may be unsuited to check health of retail 5V battery packs. As I understand it such battery packs have extra circuits to make them safe e.g. prevent overcharging. Presumably that makes it harder to measure resistance etc. Am I correct? Is it worth me buying a S60 for this?
So I'd like to find a way to check health of battery pack - ideally other than waiting to see if case starts blowing larger due to gases from deterioration (eg spinning case to see if cases have caused case to curve out). Would a low output voltage be such an indication e.g. if I only got 4.5V then it's time to chuck?
If the battery pack is ok then can I charge and draw power from it at the same time i.e. as an uninterruptible power supply? I have a pi zero that I'd like to power from a LIPO connected to a large solar cell.