Left MBA fully discharged overnight bad for battery?

[asenna]

I left my MBA fully discharged overnight, is that bad for the battery? I know lithium batteries don't like being discharged.

[filmbuff]

No, because it wasn't "fully discharged", it was just below the voltage required to run the computer. There is a chip dedicated to keeping your battery from actually discharging or overcharging.

[JoeG4]

Try not to do that again. I killed both my PowerBook G4's battery and my MacBook's battery by running out of juice and then forgetting to charge them for a day or so. When I got around to trying to charge them, the computer wouldn't recognize the battery.

The same dang thing happened to my bro's MacBook battery too!

Basically, there has to be enough power for the battery's control unit to work, and if it manages to get too low (like, you run the computer down to the point that it won't even turn on AT ALL), then after some time there won't even be enough power for the control unit, and unless the control unit has power, it won't let the battery charge.

[asenna]

Originally Posted by JoeG4

Try not to do that again. I killed both my PowerBook G4's battery and my MacBook's battery by running out of juice and then forgetting to charge them for a day or so. When I got around to trying to charge them, the computer wouldn't recognize the battery.

The same dang thing happened to my bro's MacBook battery too!

Basically, there has to be enough power for the battery's control unit to work, and if it manages to get too low (like, you run the computer down to the point that it won't even turn on AT ALL), then after some time there won't even be enough power for the control unit, and unless the control unit has power, it won't let the battery charge.

Perhaps the older batteries were more susceptible to this? There was a change in battery technology/performance when they moved up from 300 cycles to 1000 cycles of guaranteed capacity. What year was your brothers macbook?

And cheers to a Bay Area member. Its wet out there today drive safe

[2IS]

Originally Posted by filmbuff

No, because it wasn't "fully discharged", it was just below the voltage required to run the computer. There is a chip dedicated to keeping your battery from actually discharging or overcharging.

The man speaks the truth. There's essentially a "cut off switch" with laptops, once the voltage drops below a certain level, it will simply stop providing power to the machine.

[jdavtz]

I doubt it causes harm; Apple actually instruct you to do it for older MacBooks to calibrate the battery/time remaining thing, but say it's not necessary for newer models. They don't say it's harmful.

http://support.apple.com/kb/HT1490

[firewood]

The battery controller doesn't actually let the battery fully discharge. It will shut the MBA down before a dangerously low level. A consumer product Li-Ion battery is designed for several 100 to over a 1000 full discharge/charge cycles before losing half their capacity (and many many more partial cycles), so at most you will lose a fraction of a percent of your battery capacity.

[GGJstudios]

Originally Posted by asenna

I left my MBA fully discharged overnight, is that bad for the battery? I know lithium batteries don't like being discharged.

I wouldn't do it on a regular basis, but one time isn't going to hurt anything.

The link below should answer most, if not all, of your battery/charging questions. If you haven't already done so, I highly recommend you take the time to read it.

Apple Notebook Battery FAQ