Madkins007
Member
Registered: Mar 2001
Location: Nebraska- the Good life
Posts: 695 |
The "Care and Feeding" of Li-Ion, NiMH, and similar batteries is an odd issue. No two sites or sources seem to agree on the best way to treat these, and this is a subject that has been raised on this and other forums a lot.
Most sources, especially battery manufacturers, seem to agree that Li-Ion and NiMH either should be, or are at least not badly hurt by, being kept as fully charged as possible.
Note- Li-Ion batteries are NOT affected by so called 'battery memory' or 'memory accumulation', the effect that made it necessary to discharge other kinds of rechargeables as low as possible before recharging. (Source: http://www.sanyo.co.jp/energy/english/f10.htm)
With a PDA or similar device, this is also the logical choice as we want to ensure that at any given moment, the device will last for as long as possible.
The flip side is that Li-Ion batteries do not like being charged for long periods or trickle-charged, so they should not be left in a charger that keeps trying to charge them for too long. ('too long' is rarely defined, but I would not charge them for more than about overnight.)
One of the best articles I have found on this subject is here: http://www.amazon.com/exec/obidos/t...4792096-2072854
To answer EJSHUMAK's question about storage:
"Li-ion batteries should be stored charged. If they're stored for over three months with a cell voltage of less than 2.5V, unrecoverable capacity loss will occur. Also, leakage and corrosion are more likely. Some Li-ion battery packs won't allow a recharge if individual cell voltages fall below 2.5V, because at this point cells will have chemically altered and recharging could be hazardous. It's best to store Li-ion batteries charged at between 70 and 90 per cent of full capacity.
All rechargeable batteries suffer from self-discharge when stored or not in use. Li-ion batteries self-discharge by three to five per cent in the first 30 days of storage, then settle down to one to two per cent per month. With intelligent batteries, the control circuits packaged with the battery can consume as much as three per cent of the charge per month. This means that a 90 per cent charged Li-ion intelligent battery can be stored for around 18 months before falling below the minimum charge limit. Shorting out, piercing, crushing, applying a reverse current or heating a Li-ion battery can lead to very high case temperatures or even battery explosion. (Source: http://www.corrosion-doctors.org/Se...li-ion-reac.htm)"
Handspring does not recommend rechargeables instead of Alkaline AAA's, but that is because of their concern that users will mess things up more than because of the performance of the batteries (if you read between the lines a little!) Using NiMH batteries and a re-conditioning charger, and swapping the batteries frequently worked great for me! (Of course, I used the old 'command dot dot 7' trick to reset the battery type!)
I WAS mistaken on one issue- I thought NiMH was about as environmentally harmful as alkaline and NiCad, but it is not!
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Do what you can, with what you have, where you are at!
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07-26-2002 12:56 PM
Thanx 007
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