Sunday, November 15, 2015

Laptop occasionally won't run on battery power until I remove and reinstert the battery

I have a Toshiba Satellite S55-B5280.



Occasionally, the laptop will stop running on battery power. Meaning, if the AC adapter is unplugged, the laptop won't turn on; while the laptop is turned on, if I unplug the AC adapter, it shuts down immediately.



Once it gets into this state, it continues until I remove and reinstert the battery, which reliably fixes it. After the problem is fixed, the laptop runs fine on battery and the battery life is normal.



At first I suspected it may be an issue with the physical connection at the battery connector, but the laptop sometimes enters this state while sitting undisturbed on a table.




What could be the cause? Is it more likely to be a fault in the battery, the laptop's power circuitry, or the battery connector?



edit: upower shows a battery voltage of 16.7 V. Laptop has stopped running on battery entirely.



edit: I tested the battery with a multimeter, and 16.7 V is accurate. I'm not sure if that rules out the battery as a problem or not.



I tested the two fuses PF1 and PF2 (white rectangles with a "Y" on them in the photo below), and they are both short (which I assume means they are good):



enter image description here




You can see above one of the fuses, there is a zero ohm link, possibly named PR74. This connects to the pulldown to enable the battery. If I insert the battery (AC power unplugged) and measure the voltage at PR74, it is 3.1 V. Then, I try pressing the laptop power button, and PR74 remains 3.1 V. I'm not sure if this might indicate a problem.



PR74 connects to R671 (bottom right), which is 1kohm. I'm not sure where it goes after that.

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