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Battery health went down 98% in a minute

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pyth

macrumors member
Original poster
Mar 7, 2008
80
0
My computer's battery is 20 mos. old and has a charge cycle count of 313. The health has been at 100% the whole time.
It started out at a charge and health of 100% and over 60000 mAh according to both iStat and coconutBattery. Then I restarted the computer and the health was at 81% and the charge was still at 100% and I wasn't sure why, so I restarted it again and it said the health was at 2% and the charge was at 0%. However, it's working just fine and it's definitely not at 0% charge. Does anyone have any idea what's going on?
 
Try taking out the battery and making sure there is nothing blocking the connectors, or just leave the battery sat out for a while to cool down or something. Perhaps a calibration is in order?
 
tristangage said:
Try taking out the battery and making sure there is nothing blocking the connectors, or just leave the battery sat out for a while to cool down or something. Perhaps a calibration is in order?
Click to expand...

Yes it is. With 313 cycles, expect your battery life not to last very long - it's approaching end of life so for the most part, battery draining quickly is perfectly normal for this situation.
 
Reset the SMC (google it / search Apple)

I had a similar issue with a white Macbook, where it reported all kinds of bogus information (estimating 45 hours to charge, for example). After the reset, it returned to 'sanity'.

However, if the machine has reported 100% health perpetually, the info stored in the SMC might have been corrupted very early on (so it has always reported bogus data) - and it has only now corrected itself.

But reset it and find out (it's not harmful to anything else, so there's nothing to lose by trying)
 
I've got 332 cycles on a 20 month macbook. Still going strong. I think there's plenty of life left in this pack.
Steve
 
Well, the health has not always been 100%, it's dropped to 98 and the like before. However, I tried the SMC reset and nothing changed, but the health is actually at 40% while the charge is still at 100%. I'm wondering if it got its wires crossed and is calling the health the charge and vice versa. I haven't been using it, but I have been letting it drain itself out and 40% could be accurate after two days of disuse.
 
pyth said:
Well, the health has not always been 100%, it's dropped to 98 and the like before. However, I tried the SMC reset and nothing changed, but the health is actually at 40% while the charge is still at 100%. I'm wondering if it got its wires crossed and is calling the health the charge and vice versa. I haven't been using it, but I have been letting it drain itself out and 40% could be accurate after two days of disuse.
Click to expand...

The Charge % is all relative to the Health of the battery. If it says 40% health, you have more than likely lost a cell or two inside of your battery, and it is saying that it has charged to the maximum power (100%) that it can still hold.
 
Well, as anti-climactic as it is, the battery fixed itself...
I charged it up and let it die a bit and then charged it up and let it die all the way and I suppose after this calibration, it fixed itself. The oddest thing is that it lasted 5 hours before it died the whole way. So there really isn't anything wrong with the battery. :confused:
 
miles01110 said:
The art of reporting a battery's capacity is not a science. A 2% variation is nothing worth posting about, contrary to what people seem to think.
Click to expand...

You really ought to learn to read. It didn't go down to 98%, it went down 98%. As in it WAS at 100% and is NOW at 2%.
 
pyth said:
You really ought to learn to read. It didn't go down to 98%, it went down 98%. As in it WAS at 100% and is NOW at 2%.
Click to expand...

Oops, was referring to this:

pyth said:
Well, the health has not always been 100%, it's dropped to 98 and the like before. ...
Click to expand...

Anyhow, you're right- I definitely misunderstood. My statement still stands, it just doesn't apply here.
 
My battery started doing this about 3 months or so ago, and once the MacBook physically wouldn't turn on without the AC adapter, I called AppleCare.

After a fairly long call with a rather bemused operator ("6-5-5-3-5 mAh? Are you sure you are reading the screen correctly, sir?"), I got the battery replaced free of charge.

Bear in mind that this was all still under warranty, so your mileage may vary.
 
jbuk said:
My battery started doing this about 3 months or so ago, and once the MacBook physically wouldn't turn on without the AC adapter, I called AppleCare.

After a fairly long call with a rather bemused operator ("6-5-5-3-5 mAh? Are you sure you are reading the screen correctly, sir?"), I got the battery replaced free of charge.

Bear in mind that this was all still under warranty, so your mileage may vary.
Click to expand...

I wish that mine still was. Apple basically guaranteed that I would buy AppleCare from now on. And the battery isn't working anymore again, so I'm just using a PC made to look like a mac right now. I'll be taking it to the apple store when I get back home. When they tell me what they think, I'll post again.
 
jbuk said:
After a fairly long call with a rather bemused operator ("6-5-5-3-5 mAh? Are you sure you are reading the screen correctly, sir?"), I got the battery replaced free of charge.
Click to expand...

65535 mAh would heavily suggest some kind of error in the interface between the battery's electronics and the algorithm the computer uses to read the capacity (65535 = 2^16 - 1).
 
miles01110 said:
65535 mAh would heavily suggest some kind of error in the interface between the battery's electronics and the algorithm the computer uses to read the capacity (65535 = 2^16 - 1).
Click to expand...
Yes it would. However, this meant that the MacBook refused to charge the battery (or the battery refused to let the MacBook charge it) and thus the battery was next to useless, even if the cells themeselves were still fine.
 
pyth said:
My computer's battery is 20 mos. old and has a charge cycle count of 313. The health has been at 100% the whole time.
It started out at a charge and health of 100% and over 60000 mAh according to both iStat and coconutBattery. Then I restarted the computer and the health was at 81% and the charge was still at 100% and I wasn't sure why, so I restarted it again and it said the health was at 2% and the charge was at 0%. However, it's working just fine and it's definitely not at 0% charge. Does anyone have any idea what's going on?
Click to expand...

I had the same issue where my health dropped, except to only 42%; it stayed there until I did 2 full power cycles and how it is back to 94%.
 
I've got 616 cycles and a 100% health if were comparing how long can a battery last.
 
Was that an important sum to know?
Click to expand...

Yes it was. It means the maximum value that can be held in a 16-bit word is 65535 - so if the little processor/monitor attached to the batteries is also 16 bit for example, this value could indicate complete failure, or wrapping round from zero/-65535. Either way, it's a number that is going to catch the attention of any programmer or electronics engineer.
 
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