Spare batteries: to be stored charged or empty?

[pierrot]

That's a point I never could get clear:

somewhere I read that BP511 batteries should be drained empty before storing them for a long period of time,
elsewhere that they should be kept fully charged.
Where's the truth?

BTW. I would feel stupid storing empty batteries, having to wait for a full charge before a new shooting session.

Is there any batteries guru around? :shock:

[mgbeach]

this is a pretty good article on Li-Ion batteries
http://www.batteryuniversity.com/parttwo-34.htm

[pierrot]

Hehe, thanks for the link! But it preaches for a 3rd theory:
For best results, store the battery at 40% state-of-charge.
:mrgreen:

[robertwgross]

This is not suggesting that 40% charge is some magic number that you should strive for.

The point is that batteries of this type do fine when they are fully charged, or even half charged for storage. However, if you run them completely flat, that do not work well for the battery life.

As a general rule, these cameras will cut off when the battery is still approaching "flat", so this is safe.

---Bob Gross---

[S230]

I personally store it fully charged. Somewhere I read that there is difference between Lithion ION version Metal hydrate. With Lithion, there is a LIFE to these batteries and typically only a few years before they start dying. Since Lithion batteries contains internal circuit keeping it fully charged is better than it struggling for power. Never drain completely because I read somewhere that these batteries require a minimal certain voltage to work. The circuit would cut-off (Safety feature) if it drops below a certain voltage.