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Old 10-03-2021, 07:21 AM   #1
televizora
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Default HP 250G4 la-c701p constantly switching between battery and AC power

I have an issue with HP 250 G4.
When AC adapter is plugged in - the laptop works just fine
When I plug a battery, which a friend claimed that he recycled - replaced the cells inside it with new, the laptop works with the battery just fine.
When I connect the charger, the laptop charges the battery, but in about 1-2 minute intervals switches between AC and battery. Nonetheless, charges the battery.
The board is la-c701p v1.0. I found that the charge IC supports LEARN function(by command from the SMBus controller), which more or less is similar to the behaviour experienced by me.
If it works with battery, works with AC charger, then the MOSFETS should be fine. I found no issues with them, nonetheless.
Could this be a problem, caused by the battery? Because he replaced 18650 cells, but did not reset the battery controller. Or this must be issue with the charge/power IC?
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Last edited by televizora; 10-03-2021 at 07:28 AM..
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Old 10-03-2021, 12:49 PM   #2
televizora
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Default Re: HP 250G4 la-c701p constantly switching between battery and AC power

Measured all mosfets. Everything with them is fine.
On the G there are about 22V(my multimeter is not true RMS)
Measured all ceramic capacitors between the AC in and Battery.
Periodically voltages on the G of the two mosfets AC and RB just disappear fully and the system switches to battery. Then they appear again and the charge continues.
There is neither charger OV or BAT OV. I don't understand why it periodically switches between AC+charging and battery only when the battery is present and the power led switches from white to red and vice versa.
It switches between
AC FET and RBFET - G - 22V - Charging and powering the system from AC.
And
AC FET and RBFET - G 0V, BATFET - 22V, powering the system from Battery.
If some failure mode/protection is activated, I cant find the reason.
The system works normally both when only on AC power or Battery.
The only thing I can think of is some kind of issue with the recycled battery, although the battery seems to be just fine.

Last edited by televizora; 10-03-2021 at 01:04 PM..
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Old 10-03-2021, 10:41 PM   #3
mcplslg123
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Default Re: HP 250G4 la-c701p constantly switching between battery and AC power

Try with another known good battery first before proceeding to diagnosis. Too me, it seems battery issue.
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