Lenovo Ideapad C340-15IIL intermittent charging

[REpairAT]

Hi,
I had this case on at least 4 or 5 times different Lenovo Models already, never found a solution. Right now it's a Lenovo Ideapad C340-15IIL with a new OEM Battery. Also, I've got a used, but confirmed working OEM battery from a similar model.

Symptoms are always the same:
-> Charger disconnects almost all 2 seconds
-> Computer always switches between AC / Battery mode
-> Computer is fully functional in either battery OR AC mode with battery disconnected
-> Orange charging LED blinking all the time
-> Also when computer is turned off, the battery state splash screen appears all the time.
-> Leaving it plugged in and turned off, battery will fully charge after some time, yet symptoms from above don't change.
-> If I disconnect the battery with plugged in charger in a moment it says "on battery", the computer immediately turns off, so obviously the main power rail is disconnected by primary mosfet.

The laptop is in mint condition, never opened before, no liquid damage etc.
New OEM Charger and other OEM Battery did not solve the issue.
Charger voltage does not increase or change whenever it switches from AC to battery mode.

I assume it's a LENOVO problem, not an issue with this particular model. Does anyone have any experience with this?

Thanks a lot!
BR, Ray

[mon2]

Re: Lenovo Ideapad C340-15IIL intermittent charging

Hi.

1) link any schematics if on this forum.

2) which battery charger IC is onboard?

3) with all power removed, no battery, meter in resistance mode. Check the resistance of each mosfet for possible damage.

Post the markings on the top side of each mosfet linked to the charger IC.

[REpairAT]

Re: Lenovo Ideapad C340-15IIL intermittent charging

Charging IC is Intersil 88739A. Behaviour now is that it shuts down the first two mosfets after about 30 seconds of charging completely. Both mostfets are ok. I can't find any schematics neither from the laptop, nor from the charging IC

[mon2]

Re: Lenovo Ideapad C340-15IIL intermittent charging

How many pins on the ISL88739A ? 28 pin QFN package ?

NVM, found the short datasheet= 32 pin QFN

[mon2]

Re: Lenovo Ideapad C340-15IIL intermittent charging

Ok. Reverse engineer / hack it. It should be straight forward.

Meter in resistance mode (lowest scale). Remove all power.

1) Start with the battery connector.

2) The +volts connection on the battery pack will be ganged together to allow for a heavier current flow. Locate these pins.

The resistance between the pins should be ~0 ohms.

Now this group MAY be GROUND so check for it to confirm. One meter probe to the '+volts' cluster and other probe to shield ground on your logic board.

If there is NO connection (O.L.) then continue to locate the GROUND cluster. Once it is found, you know the original group = +volts.

3) Now place meter probe on this cluster and the other side to the closest inductor on the logic board = Battery charging leg of the circuit.

4) Next you should see a large arse current sense resistor which will be a very low resistance, by design. Very concerned about this leg.

Trace the one side of this resistor to the ISL mystery IC and record the pin #.

The NEXT pin on the ISL IC = should be the OTHER side of the current sense resistor. Record the pin #.

Interested to know the resistance from the current sense resistor legs back to the ISL device.

It is very possible and common that the lack of the current sense resistor feedback to the charger IC will halt the charging.

Just a thought but must be validated either way.

You can perhaps print out a random IC with 32 pin QFN package -> call it your ISL device and mark up the voltage pins as you go.

Confident that ISL has this device in the witness protection program (much like some of the techs here that once they have their fix, they vanish!!). Till next time.

[mcplslg123]

Re: Lenovo Ideapad C340-15IIL intermittent charging

Use Acer LA-H501P schematic to troubleshoot Charging IC. It uses the same ISL88739A. Schematic is available on this forum. Use search to locate it.