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My laptop battery always charges to about 84% to 87%. Once it reaches a charge level in that range, it stops charging, but Windows says it is "plugged in and charging". Because it has not reached 100%, it keeps trying to charge the battery, but instead of charging it gets very hot. It causes CPU temperatures of about 51°C (normal temperatures range from 35°C when idle, to 43°C when running an IDE and a compiler).

The machine is an HP Pavilion dv7-6157cl running Windows 7. I have set the fan in the BIOS to run continuously, and it is always on a table or some surface which allows plenty of airflow to the vents on the bottom.

I have reinstalled the battery drivers and updated all of the other drivers. Nothing seems to help. I have also tried calibrating the battery. I also tried changing several power settings. The problem persists.

However, it works correctly as long as the charge does not exceed 84%.

What might be causing the problem? Is there a way I can get Windows to stop charging the battery at about 80%? Should I get a new battery?

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Is it a Li-Ion battery? –  Christopher Chipps Dec 11 '12 at 6:13
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Battery heating can be a sign that there's a bad cell in the stack. The other cells charge up to full capacity and the bad cell then just turns into a resistor, creating a lot of heat as it dissipates the wasted current, and in the case of Li-Poly, eventually smoke. –  Fiasco Labs Dec 11 '12 at 6:38
    
@ChristopherChipps It is a 9-cell Lithium-ion battery. –  ctype.h Dec 11 '12 at 6:56
    
@FiascoLabs Interesting. If one cell in the stack is bad, the maximum possible percentage would be 88%. I am thinking that is probably what is wrong. Could you post that as an answer? –  ctype.h Dec 11 '12 at 7:01
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2 Answers

up vote 6 down vote accepted

Battery heating can be a sign that there's a bad cell in the stack.

The other cells charge up to full capacity and the bad cell then just turns into a resistor, creating a lot of heat as it dissipates the wasted current, and in the case of Li-Poly, eventually smoke.

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Replace your battery. Fiasco Labs is right. Your battery is broken and needs replacing.

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