Recently I’ve bought 8 AA eneloop (NiMH) batteries, which were to be used for my CD player.
The former ones, having been serving for up to 10 years, retired finally. But I found them still strong enough to drive my wireless mouse & keyboard. Not retired yet huh!
The reason I came up with this question is I want to keep those nice new products in good condition for years. However, it is well known that a Lithium (ion) battery ages fast — a new cell phone battery will become aged within no more than three years. So I wondered if I should follow some rules to treat NiMH batteries. So I did little research, and I think it’s enough.
It’s also well known that NiMH batteries do not suffer from “memory loss”. Panasonic has some tips here. So, you don’t have to fully discharge the battery in advance before re-charging it; instead, it is harmful to do that, as defective discharger designs which do not stop discharging at certain point (0.9~1 Volt) will damage the battery. Here this post has a detailed discussion on this issue, with some guy said fully discharging doesn’t bring in permanent damage (but he recommend not to do so).
So, I don’t discharge the battery fully every time. It is okay to re-charge it as long as the CD player runs out of power.
But I have 4 pairs of eneloops. My CD player drinks 2 each time; it will drink them up in about 2 weeks. So, should I re-charge the batteries immediately after being used up, or let it ’empty’ for a while until I use it again?
This post is the first one I see, before those two above. Guys there have come up with really good ideas. And, they have references too. Check them out if you want (but I didn’t :D ). According to an advertisement by Sanyo Corporation (huh Sanyo belongs to Panasonic now?!), self-discharging is really nothing to eneloop batteries (they maintain 75% charged after 3 years of storage). Even when used by CD player, I can tell there’s still left power in the battery, so it won’t go below 1V which brings damage. Since my storage time is really short, I don’t need to pay attention to re-charging my ones .
I followed the guys with the rest suggestions, and here’s my plan:
Number the batteries in group of 2, aka group #1, #2, #3, and #4. I have done this right after I started using them. I used a black ink marker to write tiny numbers on the white bodies.
Use one group (of two) at a time, certainly. After using up group #1, just keep them, and use #2 from then. When #2 runs out, replace it with #3, and put #1 & #2 in the recharger (with 4 slots designed for 2 groups). Store them well after charging (they sell ‘eneloop’ cases on Amazon). When #3 comes empty, keep it and replace it with #4. Repeat the procedure easily.
– END –