I've just bought a Sanyo charger for my (10 No) 2000mAh eneloops. Model MQN04A (for Australia).
According to the enclosed instructions, it says that the cells will need charging for an "estimated" period of 10 hours. (From fully discharged???)
But the instructions also say that the charger will switch off after "approximately" 16 hours as a means of "protection" for the cells.
The green LEDs stay on all the time until the charger switches itself off, so it's impossible to tell exactly when your cells are fully charged (other than loading 'em up and checking with a DMM — which is a nuisance), or whether or not you're leaving them to unnecessarily "cook" themselves for several hours more than needed. At the extreme — and depending on the cells' remaining charge — you could be charging them for anything up to 6 hours more than needed, or even up to (say) 10 or 12 hours more than necessary (to top up their charge as needed).
I've also noticed that even at the end of a full 16-hour charge, the cells remain quite hot to the touch, so I'm guessing that it doesn't have any sort of charge-detecting circuitry built-in to discontinue the actual charging process? Presumably, it's still trickle-charging right up to the 16th hour?
Is this an inherent design fault with these Sanyo chargers; will I damage and/or shorten the cells' working life. Or am I worrying about nothing?