Macbook pro battery health question

Guinness83 · Oct 21, 2009

Hey guys, my macbook is about four months old, i calibrated the battery once about a week after i got it and now istat is showing the battery health at 94% after 46 cycles. It was at 96% around friday and now it's gone down 2 percent in five days so i am a bit worried about this. I guess my question is if this is normal, should i do another calibration?

Guinness83 · Oct 22, 2009

Anyone?

I let it drain and left it overnight for at least 10 hours before recharging it again and now it shows the battery health is now at 93%. At this rate i'll be totally out of battery in a few months.

radP · Oct 29, 2009

hey i feel you! i've had my mbp13 since beginning july. i've calibrated my battery about 4 times so far and just like yours. i charge it to 100%, leave it plugged in for an extra 2 hours, then drain, and let it chill for 5 hours plus. my battery health was 97% yesterday, and just decreased to 96% today.
what's the deal? our their defected batteries out there?

ImageX · Oct 29, 2009

Guinness83 said:
... should i do another calibration?

Yes. The battery should be calibrated at least once a month.

MunkeyQ · Oct 29, 2009

Avoid doing a complete charge/discharge cycle to calibrate it too often though as it'll shorten the battery life.

ticedoff8 · Oct 29, 2009

MunkeyQ said:
Avoid doing a complete charge/discharge cycle to calibrate it too often though as it'll shorten the battery life.

How do you figure that? Maybe if it was a 12v car battery - but not a modern Lithium based battery.
The laptop battery circuitry cuts off the computer before the battery voltage gets low enough to damage the battery - just like it can't over-charge it.

Don't worry so much about the battery - use it and when it finally fails (it will), buy a new one. The batteries don't mind being ignored, and all of this recalibrating, cycling and being careful doesn't help - so why worry?

MunkeyQ · Oct 29, 2009

ticedoff8 said:
How do you figure that? Maybe if it was a 12v car battery - but not a modern Lithium based battery.
The laptop battery circuitry cuts off the computer before the battery voltage gets low enough to damage the battery - just like it can't over-charge it.

Don't worry so much about the battery - use it and when it finally fails (it will), buy a new one. The batteries don't mind being ignored, and all of this recalibrating, cycling and being careful doesn't help - so why worry?

The charge management IC will take care of preventing overcharge and under-voltage conditions, but each time you cycle any battery it reduces its capacity. So if you're recalibrating your battery every week, it's not too good for it.

I've built a few Li-ion pack chargers based around TI chips and from what I've learnt, cycling a Li-ion completely is by and large unnecessary unless it's a smart battery with an SMBUS interface.

iggibar · Oct 30, 2009

MunkeyQ said:
Avoid doing a complete charge/discharge cycle to calibrate it too often though as it'll shorten the battery life.

I beg to differ. The ONLY way I charge/discharge my battery is using it while it's charging, then use it while it is unplugged(not charging) until the battery goes down ALL THE WAY, and then start back up and charge it. Yeah, some people say it's time consuming...but I have a minute of time to spare to ensure my battery will last...and so far, it shows! As you can see from my istat, I have 200 cycles with 100% battery life

Baybe you just have a defective battery :Confused: