Lenovo X1 Extreme G3 (LPM-3 MB 19770-1) (BQ24780S)Fake charging, working on battery. Help needed

[CornholioGSM]

Hello,

Please i need help from you how to check what is bad on this device.
Laptop turns on normally on charger or on precharged battery, but is unable to charge - in system shows charging but not charging.

Originally was blown dual mosfet near gpu.

EDIT - after few mins on charger windows says 100% chaged with exclamation mark and something like "please check charger"

Charger is new original 100Watt

Motherboard LPM-3 MB 19770-1
Charging is BQ24780s
Schematics here : https://www.badcaps.net/filedata/fetch?id=2133492

[mon2]

Share the voltage to ground measurements of:

acdet
acok
regn
acdrv

on the charger ic with both the power adapter and battery connected. Be sure the battery is a known good battery.

also interested in the voltage to ground on each pin of the battery connector with the battery attached while charging.

Adding to the list - measure the voltage to ground of each pin on the DCIN1 power connector.

[CornholioGSM]

Hello,

sorry for deelay.
I have tested battery on another lenovo. Battery was charged to 80% soo looks good.

Here are results - tested on usbc charger and on square lenovo charger too - both original.

On BQ:

ACDET : 3,7V
ACOK : 2,8V
REGN : 6V
ACDRV : 20,2V

On BATT Conn:

M_BAT_IN : 16,4V (battery is charged to approx 80%)
I2C_CLK : 3,3V
I2C_DATA : 3,3V
M_TEMP : 2V

ON DCIN with square charger :

DCIN : 20,5V
ACDC_ID : 1,9V
...and led is not needed i mean


For me all looks good...what you mean?


BTW laptop still running when unplug charger.

[mon2]

ACDRV : 20,2V

This may be textbook case of the battery charger article by piernov.

Remove all power. See attached.



Measure the resistance (not diode mode) across the following mosfets:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Post each measurement for PQ8208, PQ82811 and PQ8210 for now. When the gate voltage is at the same as the source / drain voltage, often this means you have a defective mosfet in the power path. This ACDRV voltage should be a boosted voltage = adapter_voltage + REGN voltage = 19V + 6V = ~25v.

Suspecting that one of these mosfets is defective but share your measurements. Each should be hundreds of k ohms or higher else the mosfet is a suspect. Then the suggestion is to carefully flux and remove the mosfet and measure again while the mosfet is removed and on your workbench. Are the measurements still low?

[m1ch43lzm]

Boardview here: https://www.badcaps.net/forum/troubl...-lpm-3-19770-1

Also measure voltage at ACDET on battery only, should be 0V, if not, check PD8408, if it's shorted, battery voltage can leak to ACDET

[CornholioGSM]

Heh thank you for help.
It was bad PQ8211 - was shorted in all ways

Funny - i have searched for problems on mosfets near battery

MANY THANKS !!!


btw because gpu still makes problems - i have found another problematic mosfet PQA406 on DGFXCORE

Now looks all fine i mean