Loooong-term storage of Eneloop, NiMH, NiCad?

[hamlet]

I am having a difficult time finding the answer to my question concerning storage life for Eneloop, NiMH, and NiCads. This is a SHELF-LIFE question, not a cycle-life or energy storage question:

If I bought 100 Eneloop AA batteries, 100 NiMH AA batteries, and 100 NiCad AA batteries, sealed them up, & then tossed them in a drawer or perhaps in the back of the refriderator for 15 years, which type would still function well/best? Would they all be unchargeable after all that time? Would it help to charge them first before putting them away?

Thanks!
Hamlet

 

[Mr Happy]

NiCd cells are the only ones proven to have a long shelf life. A commonly suggested procedure for storing NiCd cells (individual cells, not batteries) is to drain them down to 0 V with a resistor and then store them shorted out. They probably will survive 15 years this way.

NiMH cells cannot be stored for long periods without intermediate maintenance. If you stored a regular (non-LSD) NiMH cell for 15 years, it would most likely have deteriorated beyond recovery after that time.

LSD cells like Eneloops may last better, but they have not been in existence for 15 years for anyone to find out. The most available test at the moment is that after 2-3 years on the shelf from manufacture, Eneloops still seem to be holding a charge and can recover good performance after some refresh cycles. From this data one might extrapolate out to, say, 5 years, but after that the extrapolations become very uncertain.

[Edit: I should add since it is not quite clear from the above, that you should never drain NiMH cells down to 0 V, nor store them at voltages below 1.2 V. A common suggestion for NiMH cells is to store them at about 40% charge or less, and refresh them every few months.]

 

[likeguymontag]

Battery technology will probably continue improve incrementally over the coming years. I can't see why you'd want to buy cells now that you won't use until the future. Of course, that doesn't actually answer the question you asked, so I'm not being very helpful.

 

[hamlet]

"NiCd cells are the only ones proven to have a long shelf life. A commonly suggested procedure for storing NiCd cells (individual cells, not batteries) is to drain them down to 0 V with a resistor and then store them shorted out. They probably will survive 15 years this way."

Thank you. This is what I was looking for. Do a factory-new NiCd cells come with a charge, or are they already at zero?

Would vacuum packaging NiCd cells help increase shelf-life or would the negative atmosphere pop the seals? Perhaps a flooded nitrogen atmosphere would be better?

Hamlet

 

[Mr Happy]

Here is a web page to look at:

http://users.frii.com/dlc/battery.htm

Bear in mind though, that just because someone suggested a procedure at one time in the past, this procedure might not apply to every battery from every manufacturer.

If you are really serious about storage, you should contact the manufacturer of the particular batteries you intend to store and ask for their specific advice on the subject.

 

[hamlet]

Thank you. This was all very helpful!

Hamlet

 

[hamlet]

Any ideas on the shelf-life of Li-ion rechargeables? Sanyo and Panasonic don't make decent nicads any more (sintered positive post). Do they need
to be kept from falling below a certain voltage threshold while in storage? Do they lose charge like NiMH?

Hamlet