Monday, July 20, 2015

Solution for laptop cannot detect AC adapter after performing "Battery Gauge Reset"

Solution for laptop cannot detect AC adapter after performing "Battery Gauge Reset"
(Duplicate post in-case the original thread is moved, deleted or no longer available)

Hello Ideapad users,

This is not "battery pluged-in not charging" issue. That issue is software related and can be easily changed the option whether Life or Health of battery you concerned by LEM.

I'm one of Y580 owner that facing that issue that the laptop cannot detect the AC adaptor anymore after performing the Battery Guage Reset" like you guys.

For example,

and so on.

I was tring to search for the solution, but as you know there is nothing without send it back to service center. I can say that this is the hardware, so that no s/w can be help.

The tempolary solution I was using is,
1. Remove the battery (if laptop is powering on, then shutdown it first).
2. Remove the AC adaptor from wall ac receptacle. 
3. Once the laptop is completely powered down, plug AC adaptor to your laptop and wall AC receptacle.
4. After a few second, insert battery back into the Laptop. And then, the battery will be chaged as usaul.
5. You need to repeat step 1-4 above every time you unpluged the AC adaptor.

By the way, I have been living with that issue for almost 2 years, until it was already out of waranty in June 2014. So rightnow, I can do whatever I want without worrying the waranty.

Last night, I was trying to teardown my Y580 to find the dead components. I gusted that the issue may be from charging circuit. Afetr opened the chassis, I found that the Y580 uses BQ24737 from TI to be the charging controller.

I cannot found the BQ24737's datasheet, but I was using BQ24735 instead, since, they have the same pinout with difference in optional functions.

Bingo!, I found it. The dead one is the input MOSFET. It's shorted between Drain and Source!. That lets the voltage from AC adapter directly connected to Battery. And then, the AC adapter will be tripped with over current protection and the voltage is held to near zero. That's why we cannot plug the ac adapter with battery inserted for this case.

So far, after I replaced it with the similar rating MOSFET from old laptop, it works!. So, I can plug to charge my laptop as it should be without problem.

Note that, the actual circuit shound not be exactly the same with datasheet. For the Y580, the input MOSFET (Q1 in datasheet and PQ302 in Y580) is P-Channel (AO4423), and it has the external circuitry to dive that MOSFET instead of U1. 

If your machine is in warranty, send it to service center to replace the new motherboard. If not, and you have electronic/soldring skill, you can do it by your self.

Tools needed,
1. Soldering iron (it will be easier for removing part from PCB, if you have 2 of them).
2. Equivalent electrical rating MOSFET.
3. Multimeter.

The different model, different location. Anyway, you can check whether it is the right MOSFET that need to be replace by,
1. Disconnect battrey from labtop
2. Using multumeter (ohm function) to measure the resistance between pin Drain and Source of the MOSFETs. The dead one must has very low D to S resistance (near 0Ohm) for both direction (D(+)<-->S(-) and D(-)<-->S(+)).
3. Search for the dead MOSFET's datasheet and then find/cross the new one from local supplier.
4. Just replace with the good one.

You can do it by your self with "AT YOUR OWN RISK" and, I am not responsible for broken devices.

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