Asus Rog Laptop new battery still 0% Biard issue?

[irepair559]

Hello, i have a 2020 Asus Rog Gaming laptop powers on but always 0% doesnt charge? Bought a used oem battery ( they said only couple of cycles like new ) and same issue with new batt zero %.. I measured battery terminal on board and 2 center pins measure 3v each and the 3 pins to the right measure 0.8v each so total output of Board batt term is only around 8v ? Is that normal when no battery plugged in?
When Battery plugged in then the numbers even are lower. There was a cap that shorted out but on other side of board not near battery terminal. Would that affect it? Laptop turns on and then off in the beggining but then turns on and works, just doesnt charge battery ��

[Stevedb]

Re: Asus Rog Laptop new battery still 0% Biard issue?

Check the first and second mosfet for internal short S-G , D-S and D-G they values must be in the high kohms .

[irepair559]

Re: Asus Rog Laptop new battery still 0% Biard issue?

Check the first and second mosfet for internal short S-G , D-S and D-G they values must be in the high kohms .

new to this stuff so bear with me, which mosfets exactly and whats DS and SG And DG ? 😁

These 2 mosfets?

[Bonzas]

Re: Asus Rog Laptop new battery still 0% Biard issue?

First open schematic if you have, check voltage acfet, battfet and charging IC voltage

That D, S, G mean mosfet pin

D : Drain
S : Source
G : Gate

[irepair559]

Re: Asus Rog Laptop new battery still 0% Biard issue?

First open schematic if you have, check voltage acfet, battfet and charging IC voltage

That D, S, G mean mosfet pin

D : Drain
S : Source
G : Gate

idont have a schematic. Ill search the web and see..
i can check if they are shorted though..

[mon2]

Re: Asus Rog Laptop new battery still 0% Biard issue?

No schematic needed. Locate the mosfet and it should be a common pinout across the many mosfets.

Pins 1-2-3 = source
Pin 4 = gate
Pins 5-6-7-8 = drain

[irepair559]

Re: Asus Rog Laptop new battery still 0% Biard issue?

ok i only found one mosfet near charger port thats shorted i believe . It measures 1ohm or OL (beeps) between the opposite ends.. Both ends show 19v and the next mosfet shows 19v as well but is not shorted like the first one.

[mon2]

Re: Asus Rog Laptop new battery still 0% Biard issue?

Appears to be the one attached.

Next, locate the charger IC that should be nearby.

Perhaps the 'BQ' series from Texas Instruments. Share the topside markings on the chip

[irepair559]

Re: Asus Rog Laptop new battery still 0% Biard issue?

Appears to be the one attached.

Next, locate the charger IC that should be nearby.

Perhaps the 'BQ' series from Texas Instruments. Share the topside markings on the chip

Didnt find any BQ ics but these 3 near the battery terminal

[mon2]

Re: Asus Rog Laptop new battery still 0% Biard issue?

What are the details of this laptop? Which model # ? Logic board markings that may allow us to link a schematic.

Unable to locate the charger IC in the posted pics.

Here are some ideas to hunt down the charger IC...

1) Remove all power. Meter in DIODE mode. You can also use the lowest resistance mode on the meter but with diode mode, the meter will tone beep to assist.

2) Short the meter probes and the meter should tone beep.

3) One meter probe onto the battery connector pins that show the ~8 volts. This cluster of pins will be linked to a number of mosfets. One pair will be a HIGH SIDE and LOW SIDE mosfet pair that will switch on/off to lower the ~19 volts from the power adapter to a safe charge voltage to charge the battery pack. In front of these dual mosfets will be a honker (large) coil.

So place the other meter probe onto the coil (either side). When you hear a tone from the meter -> stop. You have found the leg of the circuit that charges this battery pack.

Post your updates and at which location you find this coil. Nearby to the coil will be the dual mosfets of interest. From these mosfets, you can trace the GATE pin (with the same DIODE mode) to find out which IC is driving the GATE pin(s). This is the charger IC of interest.

[irepair559]

Re: Asus Rog Laptop new battery still 0% Biard issue?

What are the details of this laptop? Which model # ? Logic board markings that may allow us to link a schematic.

Unable to locate the charger IC in the posted pics.

Here are some ideas to hunt down the charger IC...

1) Remove all power. Meter in DIODE mode. You can also use the lowest resistance mode on the meter but with diode mode, the meter will tone beep to assist.

2) Short the meter probes and the meter should tone beep.

3) One meter probe onto the battery connector pins that show the ~8 volts. This cluster of pins will be linked to a number of mosfets. One pair will be a HIGH SIDE and LOW SIDE mosfet pair that will switch on/off to lower the ~19 volts from the power adapter to a safe charge voltage to charge the battery pack. In front of these dual mosfets will be a honker (large) coil.

So place the other meter probe onto the coil (either side). When you hear a tone from the meter -> stop. You have found the leg of the circuit that charges this battery pack.

Post your updates and at which location you find this coil. Nearby to the coil will be the dual mosfets of interest. From these mosfets, you can trace the GATE pin (with the same DIODE mode) to find out which IC is driving the GATE pin(s). This is the charger IC of interest.

The 8v is the total of all the pins, 2 center ones about 3v each and 3 others around 0.8v . Which pin should i be using?

[mon2]

Re: Asus Rog Laptop new battery still 0% Biard issue?

The center 3 volts = SMBUS interface and these 2 are used to chat with the battery pack to extract the stats like serial #; vendor name; # of charge cycles; etc.

It is the 8v pins of interest. One meter probe there -> other meter probe on a nearby coil.

NO POWER TO THE BOARD during these tests.

Meter in DIODE mode. The meter will beep a tone when you locate the correct coil. Test first by shorting your probes before starting.

This is a simple continuity test to locate the charger IC leg that creates this 8v rail to charge the battery.

[irepair559]

Re: Asus Rog Laptop new battery still 0% Biard issue?

got u ill try that tomorrow thanks !

[irepair559]

Re: Asus Rog Laptop new battery still 0% Biard issue?

The center 3 volts = SMBUS interface and these 2 are used to chat with the battery pack to extract the stats like serial #; vendor name; # of charge cycles; etc.

It is the 8v pins of interest. One meter probe there -> other meter probe on a nearby coil.

NO POWER TO THE BOARD during these tests.

Meter in DIODE mode. The meter will beep a tone when you locate the correct coil. Test first by shorting your probes before starting.

This is a simple continuity test to locate the charger IC leg that creates this 8v rail to charge the battery.

So the 3 left pins are for the positive i assume since they are red on the battery connector. The big coil to the left and 2 mosfets have continuity with the pos pins.

[mon2]

Re: Asus Rog Laptop new battery still 0% Biard issue?

Good. The charger IC must be close by.

Check to the left and also underneath the logic board. The ic may be directly underneath this area.

It will be a square black in color device.

Post the topside markings of anything resembles this shape.

[irepair559]

Re: Asus Rog Laptop new battery still 0% Biard issue?

Good. The charger IC must be close by.

Check to the left and also underneath the logic board. The ic may be directly underneath this area.

It will be a square black in color device.

Post the topside markings of anything resembles this shape.

Ok i think i found it its right under the mosfets/coils on the other side..

[mon2]

Re: Asus Rog Laptop new battery still 0% Biard issue?

Indeed you have Charger IC = BQ24780S.

Datasheet is here:

https://www.ti.com/product/BQ24780S

Download it and review the pin # details as you view from the topside of the IC.

Interested to know the following voltage readings to ground:

SMBUS SCL / SDA lines ; pins #11 and #12.

Red probe on meter on pin #11.
Black probe to ground.

Proceed with care and power up. What is the voltage reading?

Repeat for pin #12 and ground.

Checking to be sure that the SMBUS lines are not stuck.

There are similar 2 lines on the battery connector that also need to be measured. You did this earlier but confirm it.

It is this charger IC that decides when to enable the charging voltage or to enable / disable the battery mosfet to power the unit.

[irepair559]

Re: Asus Rog Laptop new battery still 0% Biard issue?

Indeed you have Charger IC = BQ24780S.

Datasheet is here:

https://www.ti.com/product/BQ24780S

Download it and review the pin # details as you view from the topside of the IC.

Interested to know the following voltage readings to ground:

SMBUS SCL / SDA lines ; pins #11 and #12.

Red probe on meter on pin #11.
Black probe to ground.

Proceed with care and power up. What is the voltage reading?

Repeat for pin #12 and ground.

Checking to be sure that the SMBUS lines are not stuck.

There are similar 2 lines on the battery connector that also need to be measured. You did this earlier but confirm it.

It is this charger IC that decides when to enable the charging voltage or to enable / disable the battery mosfet to power the unit.

were getting close

but on the website it doesnt number the pins and looks rectangle rather than square ? im assuming pin 1 is where the circle marker on the ic is right?

[mon2]

Re: Asus Rog Laptop new battery still 0% Biard issue?

See page 3 of the datasheet for the pinout.

Yes, the white dot and the white stripe (Seven Nation Army?) is pin #1.

Then count counter-clockwise.

[irepair559]

Re: Asus Rog Laptop new battery still 0% Biard issue?

Ok thise 2 pins are getting 3.3v they even have pads for testing assuming im assuming?