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Battery Storage

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VictorPS

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If I have:
1. Li-ion
2. Ni-Mh
3. Ni-CD
4. Seal Lead Acid

If I am not going to use them for a long time >1 year,
what shall I do before I keep them in store room?

To full charge it, or discharge it, or maintain their charge periodicaly?
Kindly explain.
 
Sealed (or flooded) lead acid batteries must be kept well charged. They self-discharge and sustained periods of deep discharge (less than 70%-50% of the capacity remaining) cause the plates to permanently degrade. The exact schedule depends on the brand but they usually need to be topped off at least every 6 months. Ideally they need a small trickle charge, unfortunately common "trickle chargers" actually put out many times too much current for maintaining these batteries and you end up with a slow overcharge overcharge over months or years which actually harms the batteries. But be aware that all lead-acid batteries only work for a limited number of years (5-10) anyways, even if unused but ideally maintained. "Use it or lose it".

Li-ion should NOT be stored full charged but rather at about 40% remaining. But note though that Li-ion should never be completely discharged. This won't happen if you ran it down in a camcorder for example but if you put a resistor across the cells it will. Leakage of charge typically fairly minimal. Also keep in mind these are expensive cells and permanently lose capacity as time goes on. They lose 20%/yr if stored full, that's down to 4% if you store them at 40% charge as instructed.

The point is, don't buy these in bulk, use half and keep half in storage for when the first ones run down. Don't buy them just to store them.

NiCd, NiMH- as far as I know there are no storage issues.
 
VictorPS said:
If I have:
1. Li-ion
2. Ni-Mh
3. Ni-CD
4. Seal Lead Acid

If I am not going to use them for a long time >1 year,
what shall I do before I keep them in store room?

To full charge it, or discharge it, or maintain their charge periodicaly?
Kindly explain.

Have a look at this site; **broken link removed**
Where you will find lots of useful battery information.
Klaus
 
Oznog,
Maintain 40% charge for Li-ion is a challenge to me.
Normally, how we know it is 40%?

Klaus,
thanks for the site, it really useful.


Another question,
My solar (18V 10W x2) is connect parallel and charge a SLA 12V 60AH .
When measure the terminal voltage, it is 12.7V only.
So the battery is not consider charging?
Charging must happend on 13.8V only? :?:
 
VictorPS said:
Maintain 40% charge for Li-ion is a challenge to me.
Normally, how we know it is 40%?
There is no simple answer. Probably just running it down until the device shuts off, then putting on the charger for much less than it normally takes. Or if your device has a charge meter use that.

VictorPS said:
My solar (18V 10W x2) is connect parallel and charge a SLA 12V 60AH .
When measure the terminal voltage, it is 12.7V only.
So the battery is not consider charging?
Charging must happend on 13.8V only? :?:
It depends on charge state. For example a battery that was run down to 10.5v, a 1 amp charge might only bring it up to 10.8v at first. A charge rate of 1/60th the capacity (C/60 charge) does not raise the battery voltage much. You'll probably see 13.8v only when fully charged. If you were trying to charge it at 20A it would reach 13.8v as a much lower state of charge.
If a battery is nearly full charge, 12.7v seems a bit low even for a 1A charge rate at 70F. Now be aware the battery voltage drops with temperature, a lower voltage is normal in colder temps. Google the web for the exact numbers.
 
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