Lenovo Yoga C930-13IKB EYG70 NM-B741 Battery not detected.

[mrkmpn]

Hello, I have a customer that brought this laptop in after replacing his battery. He said his original battery charge was not lasting long, and after replacing the battery with one purchased from iFixit, the charging worked for about 30 minutes and then stopped, and the battery is no longer detected by windows.

This laptop powers on when the AC adapter is connected, and my USB-C multimeter shows current being used with both ports, but the charging light does not come on, and in Windows the battery icon shows an X as if there is no battery present. If I disconnect the AC adapter, the laptop will continue to run on battery, but if I power down the laptop there is still no charging LED, and the multimeter shows no current being drawn.

I have tried the new battery from iFixit, and the customer's original battery, both of which still have charge, and another battery that was new from Lenovo, but has sat on a shelf for a long time and has no charge. I found the schematics and board view here: https://www.badcaps.net/forum/troubl...-eyg70-nm-b741 and followed the instructions from section 2.2.2 on this page: https://www.badcaps.net/forum/troubleshooting-hardware-devices-and-electronics-theory/troubleshooting-laptops-tablets-and-mobile-devices/80414-laptop-battery-charging-circuit?t=90356 and when I check the voltages on pins 12 (SDA) and 13 (SCL) on the BQ chip I get 3.29 volts in diode mode to ground with AC adapter disconnected, I get ~.9v and ~1.2v.

Am I correct that these results are "normal"? and if not can anyone recommend anything else to check? Could there still be something wrong with this BQ chip that's causing it?

[mon2]

Yes, looks normal for the SMBUS lines. They are not being shunted to ground. What is not known is if the contacts from the battery itself is reaching the charger IC.

(Carefully) review the voltage to ground on each pin of mosfet PQ13. This mosfet is used to announce that the battery is docked to the charger IC. Appears to be acting a low cost logic inverter gate.

[piernov]

Generally SCL and SDA should measure close to each other in diode mode, and more likely to be around 0.4V to 0.6V (red probe on ground as usual).

[mrkmpn]

Generally SCL and SDA should measure close to each other in diode mode, and more likely to be around 0.4V to 0.6V (red probe on ground as usual).

Thank you, they're .49, I had my leads backwards.

[mrkmpn]

Hello, I have a customer that brought this laptop in after replacing his battery. He said his original battery charge was not lasting long, and after replacing the battery with one purchased from iFixit, the charging worked for about 30 minutes and then stopped, and the battery is no longer detected by windows.

This laptop powers on when the AC adapter is connected, and my USB-C multimeter shows current being used with both ports, but the charging light does not come on, and in Windows the battery icon shows an X as if there is no battery present. If I disconnect the AC adapter, the laptop will continue to run on battery, but if I power down the laptop there is still no charging LED, and the multimeter shows no current being drawn.

I have tried the new battery from iFixit, and the customer's original battery, both of which still have charge, and another battery that was new from Lenovo, but has sat on a shelf for a long time and has no charge. I found the schematics and board view here: https://www.badcaps.net/forum/troubl...-eyg70-nm-b741 and followed the instructions from section 2.2.2 on this page: https://www.badcaps.net/forum/troubleshooting-hardware-devices-and-electronics-theory/troubleshooting-laptops-tablets-and-mobile-devices/80414-laptop-battery-charging-circuit?t=90356 and when I check the voltages on pins 12 (SDA) and 13 (SCL) on the BQ chip I get 3.29 volts in diode mode to ground with AC adapter disconnected, I get ~.9v and ~1.2v.

Am I correct that these results are "normal"? and if not can anyone recommend anything else to check? Could there still be something wrong with this BQ chip that's causing it?

I get 3.3v at pin 2. I'm getting nothing at pins 1 and 3

[mrkmpn]

Any idea if my results would indicate this being a problem with the mosfet or the BQ chip?