Lithium-ion Batteries

[Green Lizard]

Somewhat off topic... I recently bought a digital camera which uses Lithium-ion batteries.The camera instructions clearly state that the battery can be charged fully at ANY time eg after only having used half of the battery's capacity ie 'no memory affect'.

I also have a digital video camera which uses L-ion batteries (one of which has a nine hour capacity).

My question is : Are ALL Lithium-ion batteries 'no memory affect' ?

This would be very useful information.Any replies greatly appreciated.

Thankyou.

[Naples Air Center, Inc.]

Green Lizard,

Lithium Ion and Nickel Metal Hydride do not have memories, just Nickel Cadmium.

If you flatten a battery before you recharge it - some people flatten their batteries manually, and some chargers do it automatically - you greatly reduce the life of the pack. A given battery pack may last for 500 full cycles, or 2000 partial ones. If you're fully flattening the battery by actually using it, then fair enough, but do not do it as part of your recharging ritual.

"Memory effect" is now used as a general term for anything that makes a battery not deliver its full capacity. What the term originally referred to, though, is a phenomenon that's probably never actually been observed in consumer hardware.

True memory only happens in sintered plate NiCd cells (which aren't necessarily the sort of NiCd you're using, and are of course completely different from any kind of NiMH cell), and it only happens when you precisely discharge a cell to exactly the same level over and over again, and recharge it without any overcharge. True memory effect happens in satellite power systems, electronics test labs, and practically nowhere else.


Take Care,

Richard

[Green Lizard]

Thanks Richard.

[Naples Air Center, Inc.]

Green Lizard,

Always glad to help. ;)

Take Care,

Richard

[Rupert S]

although lithium ion batteries don't have a memory effect, they can be very temperamental if not looked after properly. When calibrating the battery (every 30 discharge cycles or so, the battery should be fully charged then allowed to drain at a constant rate as slowly as possible until completely empty then fully charged. After this, the battery should never be discharged below about 20% unless recalibrating it. Calibrating it can actually increase the battery life too. I've managed to increase the capacity by .2 ampere hours on my powerbook which represents about 20 minutes depending on the power usage at the time.

[fobotcso]

Interesting Rupert,

So, is there a way of getting back a Li-Ion battery - Sony to be specific - after it has apparently given up the ghost completely?

It used to be possible to "zap" an apparently dead Ni-Cad cell with a large current surge that vapourised the crystals that were acting as a short circuit within the cell. It wasn't always successful or, if it was, not for very long.

Is there an equivalent procedure for Li-Ion cells?