Please Help, Acer Aspire 3 not charging!

[roxboy1984]

HI, I wonder if anyone can please help me. Im very new to component repairs, but i repair computers for a living, just not component level as yet.

Basically i have an Acer Aspire 3 A315-54k which had a glass of water spilled on it and needless to say it no longer worked after that. i ad my guys who do component repairs repair the charging/power circuit and all is well again except im having a very strange issue whereby the battery will not charge unless its completely depleted to 0% and then it will charge when i plug it in. however if i remove the charger at any point during this process and reconnect it, i have to then wait for the battery to deplete completely again in order to try and charge it.

Once the machine is charged to 100% if i use the machine while its plugged in the battery percentage will just slowly drain until once again it reaches depletion.

What im trying to establish is whether the issue resides in the battery being damaged in the spill or something else on the motherboard that is faulty. ive eliminated chargers etc.

i just dont want to purchase a new battery if thats not the issue.

Thanks in advance for any help that can be offered.

[mcplslg123]

Re: Please Help, Acer Aspire 3 not charging!

So you mean battery percentage is slowly going down even when its plugged in?? If so most likely some mosfet in charging/discharging and/or dc-in section is leaky. So do check all these mosfets
Source(Pin1-2-3) to Drain(Pin 5-6-7-8)
Source to gate(Pin4)
Gate to Drain

The measurements should be without power adapter and battery and meter should be set in resistance(Ohms) mode.

[reformatt]

Re: Please Help, Acer Aspire 3 not charging!

Not sure about this model, but most Acers have a switch under the service door for the battery to enable it. So check that first.

[roxboy1984]

Re: Please Help, Acer Aspire 3 not charging!

So you mean battery percentage is slowly going down even when its plugged in?? If so most likely some mosfet in charging/discharging and/or dc-in section is leaky. So do check all these mosfets
Source(Pin1-2-3) to Drain(Pin 5-6-7-8)
Source to gate(Pin4)
Gate to Drain

The measurements should be without power adapter and battery and meter should be set in resistance(Ohms) mode.

Thanks for the reply. so yes the percentage is slowly going down even when plugged in. but i can get it to charge absolutely perfect once the battery goes down to 0%. The guys who did the repair changed all the MOSFETS, Caps etc in the charging circuit even changed the actual charging chip and same issue.

Is it likely that the battery could be the cause? im not familiar with how the battery internal circuitry works.

[roxboy1984]

Re: Please Help, Acer Aspire 3 not charging!

Not sure about this model, but most Acers have a switch under the service door for the battery to enable it. So check that first.

Thanks for the reply.
If this switch was an issue would it not cause the battery not to work at all?

[reformatt]

Re: Please Help, Acer Aspire 3 not charging!

If I recall, the battery works, just doesn't charge. Caught me out once.

[roxboy1984]

Re: Please Help, Acer Aspire 3 not charging!

If I recall, the battery works, just doesn't charge. Caught me out once.

Thanks, What i meant was the battery does actually charge it just has to be completely drained before it does. So i would assume that rules out the switch?

[reformatt]

Re: Please Help, Acer Aspire 3 not charging!

Probably. What motherboard is fitted to this machine? LA-H792P? If so, and it's using the BQ24781 charging IC, then review the BQ24780S datasheeet on pg 17 for charging conditions. (BQ24781 datasheet isn't available but it's primarily the same logic as BQ24780S).

Also review the first 2 input FET's (this design has 3 actually), PQB1, PQB3 and PQB4. The capacitors and resistors around these FET's are critical insofar as timing, and the BQ chip will disable charging if the timing is not correct.

https://www.ti.com/lit/gpn/bq24780s

[gurj1979]

Re: Please Help, Acer Aspire 3 not charging!

Have a look at PQZ1 MOSFET. In my case this was shorting out the entire main 19v rail and prevented charging or anything. I swapped this out with another MOSFET with 30v N Channel 58A, and I got power restored.