I left my 3.7 V Li-ion cells charging for a long time with a low current 5 V charger. Now when I check the voltage, it is at 4.31 V. The cells didn't get hot, not even warm, but I'm afraid of what this could mean, since they were only supposed to charge till 4.2 V.
Does this mean they are now useless? Or lousy? It's a lot of cells in parallel and losing them would be the worst, so I need to know if 4.3 V is not so bad or have I destroyed them, or maybe decreased the capacity?