If I use Eneloop cells in a non regulated flashlight until the out put is totaly dim or nonexistant will the cells go into reverse polarity ? If they do can they be charged or are they useless ? Would the same answer apply using the cells in a regulated flashlight until it also goes out ?
Good question.
Sometimes the cells may be restored to service -- sometimes not.
Different lights will behave differently.
At the risk of generalizing, the lights I've had that killed the most NiMHs were low powered and built for wide consumer appeal. Since most consumers use disposable primary cells it gives more value to design a light to suck alkaines dry. (I had a 10 LED Nuwai that would kill a NiMH when it first
started to dim.)
It depends on who the intended market is and what the designer really had in mind. A couple of examples:
The ARC-AAA is a real 'vampire' (Gransee's word) and is a tough one for a rechargable. Even though it is a one cell light and therefore cannot reverse polarity, it is designed for runtime on alkies and will draw NiMH or NiCD cells down beyond the point of no return.
On the other hand, LUX, CREE, P4 (etc) lights that need a higher amperage often won't run longer than a few minutes on alkalines and their drivers will often cut them off before damage is done to the cells because the designer knew that they'd be run on rechargables. I have ELEKTRO LUMENS lights that may be counted on to cut out before cell damage is done.
There have also been lights that signal you before their cells are run down too much
but still let you continue to use them into oblivion should you so desire because the designer wanted to give the user that option in life and death situations. (HDS-EDC)
Often electronic equipment without motors (like radio recievers) will kill cells
unless they are designed for HAMS, who have a tradition of using rechargables. I have an MP3 player (RIO) that allows me to select cell type in the Options to avoid damage. Way cool.
I didn't mean to sound all over the place on this but sometimes it can be tricky. One thing you can do is to try to run the light or device on alkies until it dies -- then measure how much is left in each cell. I'm not sure what the limit should be but if the voltage of the expired cells is below 1 or 1.1 volts it may not be a good idea to run it on rechargables.
I've never done that -- I just occasionally get burnt and then I don't feed those devices rechargeables again. Fortunately,
usually only one is toasted when this has happend to me.
As complex as it sounds, the negatives are pretty small -- at least with us. It has really saved us a lot over the years, aside from the fact that it's very handy to just
not run out of cells.
