Acer Chromebook Spin CP713-2W

[Moosiv]

morning guys, I have a really weird issue, Acer Chrome book - dead battery - not seen by the laptop. I've bought 2 new batteries, from different places but I think they are from the same manufacturer judging by the print on them. Scenario is this. Had to plug power in before battery initially for the device to turn on - charged the battery, removed charger and tested discharge rate for a while and it seemed fine. couple of days later it won't switch on - disconnect battery, plug charger in, turns on, connect battery and it's fine. Saturday I kept switching it off and turning it back on no issue - let it sleep and it wakes no problem - left it sleeping Saturday and this morning (Monday) it wakes no problem.

The issue seems to be if you turn it off and leave it longer than an hour it will not power off the battery, you have to unplug battery - plug charger and plug battery back in. If left for 10 minutes, 20, 30 minutes it will switch back on using only the battery, but not after an hour. I'm baffled - have you any suggestions at all before I call this one a non repair?

[mon2]

Re: Acer Chromebook Spin CP713-2W

Link or post the schematic.

Locate the charger IC. Likely it will be the BQ series from Texas Instruments. Post all the top side markings of this IC.

[Moosiv]

Re: Acer Chromebook Spin CP713-2W

Hi, sorry, I've not been able to find a schematic. THE bq is BQ25710

[Moosiv]

Re: Acer Chromebook Spin CP713-2W

Sorry, I should mention, when it fails to power on the USB C charger is only pulling 5v. I have to unplug battery and charger, plug charger in and it goes to 15v.

[mon2]

Re: Acer Chromebook Spin CP713-2W

The unit works fine if the battery is always removed from the logic board?

Download the datasheet for the charger IC from the TI.COM website.

Remove all power -> meter in resistance mode.

Measure the resistance across the P-channel mosfet (used for the battery mosfet) that is the power path to/from the battery.

It is possible that this mosfet is leaky.

Check the resistance of:

source (1-2-3) & drain (5-6-7-8) ; assuming the package is common with 8 pins
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)


Post each measurement. Checking for a low resistance which often means the mosfet is defective and needs to be replaced.

[Moosiv]

Re: Acer Chromebook Spin CP713-2W

if the machine is not switched off it runs fine, if it sleeps it wakes fine. but if you switch it off and leave it for more than say 50 minutes it will not power on - the blue power light flicks on then off and that's it - you have to unplug battery, insert charger, plug battery in and it will work fine. if you switch it off and try to turn it on again within 50 minutes it will turn on fine.

Measuring source to gate and drain to gate = OL - measuring source to drain I get 17kohms

[mon2]

Re: Acer Chromebook Spin CP713-2W

The 17k is low. Reverse the leads and measure again. This part may be defective or appear to be due to surrounding components.

[Moosiv]

Re: Acer Chromebook Spin CP713-2W

red probe on source now reads 8kohms to drain - red probe on drain reads OL to source

[Moosiv]

Re: Acer Chromebook Spin CP713-2W

I don't have any p channel 20v mosfet here so I'm going to place an order with mouser - will let you know how it goes in a few days - thanks a lot for your help.

[mon2]

Re: Acer Chromebook Spin CP713-2W

Remove this part off the board and measure the same details while it is on your work table.

[Moosiv]

Re: Acer Chromebook Spin CP713-2W

OK - red on source black drain 0.01kohm - red on drain lack on source 0.01kohm

[mon2]

Re: Acer Chromebook Spin CP713-2W

The mosfet is dead. Do replace it. If ordering from Mouser, might be a good idea to check the other mosfets that are linked to the charger IC. Just in case someone else needs to be replaced.

[Moosiv]

Re: Acer Chromebook Spin CP713-2W

ok dude - thank you! I did double check using diode mode. I shorted drain to gate to discharge. Red probe on source black on drain and get 0.445 - should be OL right?