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Registered Member #60240
Joined: Mon May 16 2016, 07:01PM
Location:
Posts: 304
Two rechargeable batteries, one NiCd battery D and one NiMH battery C can not be recharged after 2 years of very moderate use:
Both batteries were used in two different groups of each four identical batteries of the same type. The three others of each group still work perfectly.
Now my question:
Please who knows successful refreshment procedures of such batteries from personal experience?
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
If the voltage across them is near to 0V then I suspect the growth of dendrites, if so, BRIEFLY connect across a high current source such as a car battery, this will vapourise the dendrites and then the cell should be able to take a charge, if that works then a couple of charge/discharge cycles will help reduce internal leakage currents I believe.
Registered Member #65
Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155
NiCd can be deep-cycled to slowly remove the memory effect, but NiMh are only good for around 300-500 charge cycles. (This method will not recover degraded energy storage capacities.)
IIRC dendrite growth is more of a LiIon/LiPol issue, but NiCd/NiMh cells will also degrade under self-discharge conditions.
If you keep: LiIon/LiPol >80% charged you get >4000 cycles LiIon/LiPol >50% charged you get >2000 cycles
NiCd/NiMh must be fully discharged to <5% to properly use a charger. A deep cycled NiCd can last 5 years with daily use, but its self-discharge rate gets worse over time. I have never seen a NiMh cell last more the 800 cycles (seem to more rapidly degrade in cold weather), and they can slowly vent off H2 that corrodes electronics in sealed enclosures.
One can replace the NiMh cells for under $2, and you should use the highest Ah capacity that will fit to extend operational life spans.
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Refreshment of rechargeable batteries?
