I’d like to make sure I understand the subject question.
I closely monitor my Li-Ion batteries at each charge, logging voltage before and after but I’ve never used them in multi-cell lights until now.
I’ll be using AW protected 14500s, I charged them tonight. I know I need to have the same voltage on each cell prior to installing them into each light (2 lights, 2 cells each) but how close a match do I need?
They came off the charger at 4.15, 4.14, 4.14, 4.14 ten minutes off the charger. Off the cuff, I’m thinking these are well matched cells (measurements taken with a Fluke 88). Am I ok?
These two lights are on my bike, I ride a couple of times a week for 20 minutes or so, should I pull them out between rides? Measure voltages between rides? Make sure they’re within 1/100v before I put them back in?
Well, the protection circuit is supposed to do its job, saving you all those hassle. The biggest danger of serial li-ion config would be reverse charging, which happens when
1. One battery is totally depleted
2. The other battery is still strong
3. The light still works, e.g allow strong current to flow through despite the voltage drop.
When all these happens, the depleted battery will no longer give out charge but instead it received charge on reverse, pushed by the other battery. In li-ion case, it could mean kaboom.
As you can see, scenario #1 would not happen in your case if your protection circuit works. The weak battery simply shut off and become open-circuit.
Just try not to use up too much juice from your cells between charges. Try the lights for about 10 min and then take a reading. Another 10 min and then another reading. And so on until you get an idea of how your light uses the cells.