Lenovo G40 strange problem .

[mo000]

hi .
i have lenovo G40-80 ACLU3/ACLU4 NM-A361 power on with the battery only if the adapter present and keeps on even i remove the adapter but without adapter and with the battery only the laptop turns on for 2 sec and goes off

the laptop charging the battery and working on battery fine but if i turn it off no power on again on battery unless i insert the adapter .

with the battery only
i have 16v on pin 1 and 2 of battery connector
3v on pin2 and 0.3 on pin3 and 3VALW present only when i press on powerbtn .

i change the battery with working one but same problem
i try to update the bios from the windows but when the laptop restart to complete bios update shows message **the update bios failed no connected battery ** but the battery is connected and fully charged .

[mon2]

Re: Lenovo G40 strange problem .

i have 16v on pin 1 and 2 of battery connector
3v on pin2 and 0.3 on pin3 and 3VALW present only when i press on powerbtn .

Can you clarify ?

Do you mean 3v on pin 3 and 0.3 on pin 4 of the BATTERY CONNECTOR ?

Is PD305 present on your board ?

[mo000]

Re: Lenovo G40 strange problem .

Can you clarify ?

Do you mean 3v on pin 3 and 0.3 on pin 4 of the BATTERY CONNECTOR ?

Is PD305 present on your board ?

yes of the battery connector
PD305 not present on the board .

[mo000]

Re: Lenovo G40 strange problem .

any help ?

[mon2]

Re: Lenovo G40 strange problem .

Review the main power rail with only the charged battery. What is the voltage?

This voltage travels from the battery to the main rail through the 'battery mosfet'. It may be defective but check the voltages on the mosfet pins.

Interested in the following:

Pin 1-2-3 = source pins.
Pin 4 = gate pin.
Pin 5-6-7-8 = drain pins.

Check the voltage to ground of this mosfet.

[mo000]

Re: Lenovo G40 strange problem .

Review the main power rail with only the charged battery. What is the voltage?

This voltage travels from the battery to the main rail through the 'battery mosfet'. It may be defective but check the voltages on the mosfet pins.

Interested in the following:

Pin 1-2-3 = source pins.
Pin 4 = gate pin.
Pin 5-6-7-8 = drain pins.

Check the voltage to ground of this mosfet.

I check the mosfet PQ303
sourc and drain = 16v
gate =0v

[mo000]

Re: Lenovo G40 strange problem .

any help?

[mon2]

Re: Lenovo G40 strange problem .

I think that I may not have the proper schematic.

1) If you have it - please post it or link it if it is on this forum.

2) Locate the charger IC on the logic board and share the details. It should be close to the DCIN adapter connector. Post the full markings on the IC.

The ACTUAL schematic may not be available but let us continue with the G40-70 schematic which appears to be similar.

a) PQ303 appears to be allowing for the battery voltage to reach the logic board.

b) without the AC adapter, using only the battery, allow for the logic board to turn ON. After it turns off, measure again the voltages on PQ303.

Post the readings.

[mon2]

Re: Lenovo G40 strange problem .

Confirm again the voltages of the SMBUS signals - check the voltages BEFORE and AFTER each of the series resistors.

If the logic board is not able to detect the battery, then most likely the SMBUS communications is failing. SMBUS (I2C) is used to communicate with the BMS (battery management system) logic board that is inside the battery pack. This BMS board holds the model / serial # / # of charge cycles / configuration of the battery pack.

If you allow for the logic board WITH the battery & AC adapter to boot into Windows -> does Windows show detection of the battery ?

[mo000]

Re: Lenovo G40 strange problem .

I think that I may not have the proper schematic.

1) If you have it - please post it or link it if it is on this forum.

2) Locate the charger IC on the logic board and share the details. It should be close to the DCIN adapter connector. Post the full markings on the IC.

The ACTUAL schematic may not be available but let us continue with the G40-70 schematic which appears to be similar.

a) PQ303 appears to be allowing for the battery voltage to reach the logic board.

b) without the AC adapter, using only the battery, allow for the logic board to turn ON. After it turns off, measure again the voltages on PQ303.

Post the readings.

i use only the battery the voltage on PQ303 source and drain = 16v gate=0v

[mo000]

Re: Lenovo G40 strange problem .

Confirm again the voltages of the SMBUS signals - check the voltages BEFORE and AFTER each of the series resistors.

If the logic board is not able to detect the battery, then most likely the SMBUS communications is failing. SMBUS (I2C) is used to communicate with the BMS (battery management system) logic board that is inside the battery pack. This BMS board holds the model / serial # / # of charge cycles / configuration of the battery pack.

If you allow for the logic board WITH the battery & AC adapter to boot into Windows -> does Windows show detection of the battery ?

the voltage ON SMBUS=3.3V
yes windows detect the battery and the percent of charging .