[ccwillows]

I just received an extra macbook pro battery and would probably only use it if I were flying or as a backup if my main battery fails.

Are the MBP batteries storable? If so, are they best stored fully charged or fully drained?

Any help is appreciated.

[icruise]

As I understand it, it's best to store them charged and to take them out every once in a while to charge them up, even if you aren't going to use them.

[tooki]

The optimal storage charge level for Lithium-Ion batteries is 40%. Then put it in an airtight bag and stick it in the fridge (but not the freezer).

Check it every month or two, and charge back to 40% if needed. It's EXTREMELY harmful to Li-Ion batteries to be deep-discharged.

tooki

[ccwillows]

Originally Posted by tooki

The optimal storage charge level for Lithium-Ion batteries is 40%. Then put it in an airtight bag and stick it in the fridge (but not the freezer).

Check it every month or two, and charge back to 40% if needed. It's EXTREMELY harmful to Li-Ion batteries to be deep-discharged.

tooki

Thanks for the follow up.
Aren't these macbook pro batteries lithium-polymer? Is there a difference or do they require the same type of storage?

[tooki]

Lithium-polymer is just one type of Li-Ion battery. The above instructions will serve you well.

Oh, and of course the battery should be allowed to warm up to room temperature BEFORE removing it from the storage bag, to prevent condensation.

tooki

P.S. this is the source for the instructions: http://www.batteryuniversity.com/parttwo-34.htm (Apple's battery page, http://www.apple.com/batteries/notebooks.html , suggests a 50% storage charge, so clearly something in that ballpark is ideal.)

[tooki]

P.P.S. Note that the suggested operational temperature range for the computer in use tries to balance a low temperature (which preserves the battery's overall lifetime, and keeps the computer parts cool) against a warm temperature (which increases the battery's immediate run time). For storage, cold is ideal, but a cold battery won't yield its full stored energy until it warms up.

[ccwillows]

Thanks for all the info, by the way. Those were great links. I am thinking of selling the extra battery rather than hoping it stores well over time.

[newtech]

Better idea is to use both batteries in rotation until one gives up the ghost.

[tooki]

Not really. Since Li-Ion batteries deteriorate appreciably even in storage (though proper cold storage limits the deterioration significantly), it's generally better to wear out a single battery and then get a brand new one.

tooki