Shelf-life of Ni-Mh batteries?

[johnny13oi]

Hey guys, did a quick search and found some threads back from 2002. Didn't get a definitive answer though, I was just wondering what the shelf life of NiMh batteries are. I have about a large amount of Ni-Mh batteries and a lot are still in their package. I was wondering, if I were to leave them unused for a few years, would this cause any damage to them or to lose some capacity? I mainly have the Low Self Discharge batteries if that makes any difference.

 

[SilverFox]

Hello Johnny,

To keep NiMh cells vibrant, the shelf life is 30 days...

Tom

 

[johnny13oi]

Hello Johnny,

To keep NiMh cells vibrant, the shelf life is 30 days...

Tom

Oh, so I should try and use each cell atleast once a month? Even the packaged ones?

 

[dano]

I think he's asking if the cells aren't used, how long are they usable for?

I have several Panasonic 1800MAH NiMH's that are at least five years old. They weren't leaking, so I charged them, and they work fine.

There are a lot of factors, though: storage environment, past usage, brand type, leaky seals, etc.

--dan

 

[johnny13oi]

I think he's asking if the cells aren't used, how long are they usable for?

I have several Panasonic 1800MAH NiMH's that are at least five years old. They weren't leaking, so I charged them, and they work fine.

There are a lot of factors, though: storage environment, past usage, brand type, leaky seals, etc.

--dan

Well I'll try to narrow down the factors? All unused cells inside their packaging brand new, stored in a room at about 70F to 80F, mainly RayOVac Hybrid batteries with some Kodak Pre-Charged's, and I don't know about the leaky seals but I am assuming no because they're new?

 

[SilverFox]

Hello Johnny,

Dan is correct... I was being a bit of a smart alack.

To keep cells vibrant, they need to be put through a charge/discharge cycle every 30 days and stored in a discharged state.

If you can tolerate reduced performance, you can discharge them, then put back around 500 mAh of charge. In this condition they can sit for 3 - 6 months.

General storage is about 2 - 3 years, but if the voltage drops below 0.9 volts per cell, you may have problems with them heating up during charging, and they will have reduced capacity and lower voltage under load.

In general, NiMh cells prefer to be used and run into problems when stored. The general plan is to have as many cells as you frequently use on hand, then pick up a couple of extra cells for back up. This way you are constantly using all of your cells and don't have to worry about storage.

The older cells, like Dan has, are more robust and can handle more abuse. The newer higher capacity cells tend to be more fragile and require more care.

The low self discharge rate cells are different. We don't know yet about the effects of storing them. They are too new.

Tom

 

[Hans]

The older cells, like Dan has, are more robust and can handle more abuse. The newer higher capacity cells tend to be more fragile and require more care.

My oldest set is a set of Sanyo 1600's. No idea when I got them, but they're still very close to their rated capacity despite some considerable abuse over the years. I find that the cells rated 2500 and higher are far more fragile than the older cells. Even my Sanyo 2300's are a bit suspect, compared to my older Sanyo 2100's.

Hans