How long does a Li-ion battery keep a charge?

[MillCreek]

I just bought some spare BP511A batteries from SterlingTek, and I am going to charge a couple of them up and keep them as spares in my various camera bags. I have three that I use most frequently, and want to keep a charged spare in each. The question that I have is: how long would one of these batteries hold a charge? Would I have to dig them out and charge them up once a week to be sure that they are usefully charged when needed?

I thought I had read somewhere that nickel-cadmium rechargeables can lose up to 10% of their charge per day. I haven't the faintest idea on the rate of charge loss for lithium-ion batteries. Any suggestions are welcome.

[Ephemeral]

I vaguely recal someone posting a link to an article on here about LION batteries quite recently.

From memory...they hold charge well, but actual their ability to hold charge decays over time from the date that they are made. How much charge they have while stored also affects their rate of decay.

[Raymate]

Very well, about a few months at least. If they are new cells use them for a few cycles just to get them working, then you could charge them ready. I would cycle them around every few months so they do get used.

NiCD are about 2-3% per day
NiMH are about 1-2% per day

Also NiCD and NiMH should not be stored charged, if you want to store them then use them before you do. LiON can take more abuse once they have settled after the first few charges (the first charge should be longer than needed then let them go flat until the camera turns off, then repeat about five times after this you can charge at any point to top them up)

[foty89]

This thread contains a link to a wikipedia article that contains EVERYTHING you would ever want to know about these batteries:

http://photography-on-the.net/forum/showthread.php?t=197565

[Ephemeral]

Ah, that's the article I was refering to.

:D