Can AA Ni-MH batteries be stored long-term for an indefinite period of time without any 0% charge and without causing irreversible damage to the battery?
No Ni-MH batteries will slowly lose a charge. Panasonic https://eu.industrial.panasonic.com/sites/default/pidseu/files/downloads/files/id_ni-mh_1104_e.pdf recommeneds with long term storage, they still need to be recharged once a year for their industrial ones.
Regards,
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This type of AA Ni-MH battery can remain uncharged for how many months without causing any permanent damage to the battery?
my brands Mox and Toshiba
my house temperature varies 33-36C
That’s just one example.
We don’t’ stock Mox or Toshbia, you should contact them directly for product verification…
For Nickel Metal Hydride AA chemistry on our line card today, one we stock is PKCELL: Nickel Metal Hydride AA Batteries Rechargeable (Secondary) | Electronic Components Distributor DigiKey DataSheet: https://mm.digikey.com/Volume0/opasdata/d220001/medias/docus/427/NIMH_AA2000_DS.pdf
Which requires: Cycle(charge and discharge) the battery every 3-6months to maintain cell/battery performance when being stored for an extended period of time.
Interesting, Duracell, Energizer, Panasonic, and FDK dont’ directly recommend cycle times in storage…
Regards,
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The data seems to vary by vendor and none of them are clear as to the answer. One thing that is clear is that the batteries should be removed from any device so that they do not have any load at all on them during long-term storage.
From various documents I have read, it seems unlikely that there would be permanent damage to the batteries if stored removed from any device and kept between -20° C and +30°C. It is preferred to recharge at least yearly, but some documents implied that this was not critical. However, if not recharged yearly, the capacity would be reduced when one finally does recharge them. It sounds like the capacity will often increase again somewhat after a few charge-discharge cycles.
Most documents I read did indicate that storage above +30°C would increase the risk of permanent reduction in capacity and possibly damage due to chemical deterioration. As such, there is no definite answer to your question. Storage above +30°C and not recharging yearly will have a much greater risk of deterioration and premature failure.
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they self-discharge and I don’t know if I can store them without charging if permanent damage will occur
in May I charged them 100% and stored them but I don’t know when I load again here the temperature is 35c
the temperature in my house is impossible to reduce, it varies between 33-36C
but I could charge the AA Ni-MH battery annually, but I have not found any pdf information or study showing that charging once a year is enough even if the temperature is 36C
I would like to avoid as much as possible permanent damage to these batteries during long-term storage
Can any battery chemistry engineer help me?
Hopefully there is someone with a specialization in battery chemistry that can weigh in but for the time being, we know that two major factors are annual charging, and storage temperature. If you are storing them at above 30C then you lose out on the temperature advantage, and while annual charging will still help, they will degrade faster than batteries stored under optimal conditions.
That said, this “damage” is in all likelihood going to look more like a loss of maximum capacity year over year rather than a catastrophic failure or total degradation after X months. In order to avoid this loss of capacity, the answer is to store them at a lower temperature, I don’t believe there is a way around that.
The temperature in my case is difficult to reduce, I want to avoid as much permanent degradation as possible when storing AA Ni-MH batteries at this temperature.
With the higher storage temp, you may have to recharge them more often. You should check with the manufacture of the batteries, and see what their recommendations are.
I asked mox and toshiba they never answered how many times a year to charge these AA ni-mh batteries stored at 36C temperature and whether it is to charge 50 or 100%
I could not find any information like how many times a year to charge the batteries at that temperature. Though I found an Energizer guide on the NiMH batteries on this link: https://data.energizer.com/pdfs/nickelmetalhydride_appman.pdf
There is a chart on page 7 showing voltage and temperature. There is more information how temperature and battery behavior. Hopefully this helps.
I have Ni-MH AA batteries here in my house, the temperature varies 35C, what percentage should I charge these batteries and what is the annual frequency of recharges to keep them in good condition? Their original charger does not have a % meter display.
From personal experience over the weekend, if they sat for 6 months they are probably almost dead and need to be re-charged.
Regards,
in temperature 35C recharge 100% in 7 months is good for previne damage battery useful life?
@kesadav882 it’ll be a good test… Recharge your batteries up to 100% and let us know in 6 months!
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I charged all of them (12 batteries) at the beginning of May 100% today I tested all my Ni-MH AA batteries using a digital multimeter and the voltage dropped and varied from 1.08v to 1.25v. Is it possible to generate a charging schedule to maximize the maximum useful life of these batteries even with storage between 33-35C?
1.08v to 1.25v is already critical for the useful life of AA Ni-MH?
For the longevity of the Ni-MH AA battery life, is it better to charge 50% every 2 months or charge 100% every 4 months?
here actually i charger 100% after 4 months it drops to 1.08v the temperature in my house varies between 33-35C
Energizer has a good Writeup on this and recommends room temp storage at about an 80% charge; anything above 80 and the charge level itself will expose the battery to more chemical pressure.
In your specific question the 50% charge would be the most prudent option.
See here for their document on it. (search for “self discharge”)
yesterday I charged 100% after 4 months it drops to between 1.08v and 1.25v the temperature in my house varies between 33-35C I don’t know when to charge again my original charger doesn’t have a percentage meter