Did I damage my battery?


macrumors 6502a
Original poster
Jan 5, 2011
I have a 2012 MBA with about 250 cycles on the battery. It has always lasted 6-8 hours and the battery health app said 83% until last night.

I left the laptop in my car for about 2 hours in -15°F conditions. When I got it out and turned it back on it was very cold, and battery health said 63% life and the battery indicator said "Service Battery". It kept saying that even after the comouter warmed up to room temperature. I let the battery run down to 0 to calibrate it overnight then plugged the mac back in. The LED on the charger is now green. I haven't turned it back on yet to see if it will charge.

Help? I would hate to have to send this in to Apple when it had a perfectly good battery up until yesterday. The nearest Apple store is 150 miles away.


macrumors 6502
Jun 23, 2003
I'm no expert but I'm going to guess you might have reduced the capacity of the battery a bit but it should work fine. It would have been worse to leave it extreme heat.

Mr Rabbit

macrumors 6502a
May 13, 2013
I wouldn't think that it would be damaged from that amount of time in that environment. Even though it's -15 outside I'd imagine the interior of your car only dipped into the low 20's or so, given it was likely warmed up while you were driving beforehand.

When you brought it inside did you first let it acclimate to room temperature or did you power it on while it was still really cold? My main concern would be condensation formed internally if it managed to heat up quickly enough when booted while cold.

You've already calibrated/conditioned the battery with a full charge cycle, I'd recommend taking it a step further and resetting the SMC. On your MacBook Air you would do so using these steps...
  • Plug your MagSafe into the wall and into your MacBook Air
  • Shut the MacBook Air down normally ( > Shutdown) if not already powered off
  • Hold shift + control + option while pressing the power button
  • Hold all four keys for 2-3 seconds (you might see the MagSafe LED change color during this step)
  • Release all four keys at once
  • Wait a second or two then press the power button


macrumors regular
Jul 16, 2007
Same thing happened to me last month in the bitter sub-zero cold. I accidentally left my briefcase in the car trunk. Next morning my battery was at 5% of capacity with "service" indicator. Had to swap out battery at Apple store. BTW, tried all the suggestion by Mr. Rabbit (which they again repeated at the Apple store). Good news was that it was only an hour wait to swap batteries. Bad news is that it cost $179.


macrumors 6502a
Original poster
Jan 5, 2011
I don't know why I didn't think of an SMC reset earlier. Thinking about it the problem is probably due to condensation rather than the cold. I had it in sleep mode so the power was still on and it did get condensation on it when I brought it inside.

I shut it down and tried the SMC reset and the LED changed to orange but as soon as I powered it back on the LED went green. When I unplugged it it shut off immediately as if there was no battery. Next I tried an SMC reset with the power unplugged then pressed the power button and finally, it worked! The laptop is now running on battery power and it says 60% charged but it still says "Service Battery". Battery Health shows 75% healthy now, which is an improvement.

I'll give it a couple of days to 'recover' and see what happens.


macrumors 65816
Jun 28, 2010
Recently, I dealt with a "dead" MacBook Pro - it was weird because nothing would start it up, despite working perfectly well the day before. The battery should've been fully charged, and plugging in the AC adapter would not light up the LED on that Mac (switching with another showed the AC adapter was good). After a few tries, I finally opened it up (it was out of warranty), disconnected the battery, waited a few seconds, reconnected it, and the computer started up just fine. I know the Airs are technically not "user-serviceable", but the same process might work on a whim before you get a new battery (you'd just need a pentalobe screwdriver, then disconnect and reconnect the battery connector).