Battery Statistics
An easy way of finding out about the health of your MacBook/MacBookPro battery is to use this little command line.
$ ioreg -w0 -l | grep Capacity
"CurrentCapacity" = 5259
"LegacyBatteryInfo" = {"Capacity"=5279,"Voltage"=12596,"Flags"=7,"Current"=5259,"Amperage"=267,"Cycle Count"=48}
"DesignCapacity" = 5500
"MaxCapacity" = 5279
MaxCapacity is the current capacity your battery can still hold on a full charge. DesignCapacity was the original capacity. So if the difference gets too big your battery is probably end of life and ready to be replaced. Most likely the related Cycle Count is high then as well.
It would actually be a neat little project to collect this information over time with RRDTool. If you are OK to shell out a few bucks there already is a software called ibat that seems to do this.
Update: There is also a freeware tool called coconutbattery that shows this information in a nice UI.
Interesting command line. Thanks Torsten!
Here are the results on my MBP:
$ ioreg -w0 -l | grep Capacity
“CurrentCapacity” = 2579
“LegacyBatteryInfo” = {”Capacity”=2649,”Voltage”=12410,”Flags”=5,”Current”=2579,”Amperage”=0,”Cycle Count”=172}
“DesignCapacity” = 5500
“MaxCapacity” = 2649
These statistics confirm my feeling that my battery lasts only half the time than when I got it, one year and 7 months ago.
iStat Pro displays this information, too. And my first generation MacBook Pro with once replaced battery (remember the “we need to replace your battery” recall?) is still at 85% health after 148 cycles.
Very interesting. My wife was concerned about how she should charge/discharge her new macbook and I wasn’t sure.
I ran this command for her, but the results don’t make sense. How could her MaxCapacity be higher than the DesignCapacity?
She’s had the laptop for about seven months and it’s been on almost 24/7 since then. I was really surprised by these results. It doesn’t seem right, but I know nothing about how this stuff works.
“CurrentCapacity” = 4804
“LegacyBatteryInfo” = {”Capacity”=5167,”Voltage”=12269,”Flags”=4,”Current”=4804,”Amperage”=18446744073709550419,”Cycle Count”=142}
“DesignCapacity” = 5020
“MaxCapacity” = 5167
@Aaron: That’s indeed very strange!
My suggestion: contact the author of ibat. I am expecting he might have some clue. And then let us know! :)
Hi
I actually have the same thing happen:
855 Cycles
4935 mA
on a more than 2 year old MacBook.
It was a result of upgrading from tiger to leopard, that is a least my best guess.
I’ve followed Apple’s instructions for recalibrating the battery ( http://support.apple.com/kb/HT1490 ) twice so far, and coconutBattery has reported an increase in current maximum capacity each time.
Not sure yet if the battery life actually is longer, but I’m hoping so. The process is a bit fiddly, but might save me shelling out for a new battery just yet.