Acer SF314-41 battery not detected

[Ado02]

Hi,

I am working on a Acer SF314-41 laptop where the battery is not detected.

The laptop works off the charger and the battery but it's not charging or showing the battery in Windows.

Charger IC: BQ24781

BATPRES - 0v With Battery and 3v Without when the charger is plugged in
SDA - 3.2v
SCL - 3.2v

Battery Connector:

BT+ 7.2V
BI 0v
BAT_IN#_1 0v
BATA_SCL_1 3.2v
BATA_SDA_1 3.2v

Update: Brand New Battery Installed Prior To Any Measurements Were Taken

Where to look next?

Mod Edit - Link to schematic https://www.badcaps.net/forum/showthread.php?t=117526
Reminder: rules and organization of this section - https://www.badcaps.net/forum/showthread.php?t=117483

[mon2]

Re: Acer SF314-41 battery not detected

Test with another known good battery (Amazon?).

[Ado02]

Re: Acer SF314-41 battery not detected

Sorry, I forgot to mention - I installed a brand-new battery.

[mon2]

Re: Acer SF314-41 battery not detected

BAT_IN# (battery connector) should remain LOW as long as the battery is connected. Respectively, this signal BAT_IN# = PWR_CHG_BATPRES# = BATPRES# (pin 15) on the charger IC.

Again, the charger IC @ BATPRES# should remain low as long as the battery is attached. If this pin #15 on PU4403 goes logic HIGH (3v3) then the battery is considered to be absent.

[Ado02]

Re: Acer SF314-41 battery not detected

BAT_IN# (battery connector) should remain LOW as long as the battery is connected. Respectively, this signal BAT_IN# = PWR_CHG_BATPRES# = BATPRES# (pin 15) on the charger IC.

Again, the charger IC @ BATPRES# should remain low as long as the battery is attached. If this pin #15 on PU4403 goes logic HIGH (3v3) then the battery is considered to be absent.

BAT_IN#_1 is 3.26v when the battery is disconnected and Pin 15 on Charger IC is also 3.26v. When the battery is connected it drops to 0.300v.

I hope this helps.

[mon2]

Re: Acer SF314-41 battery not detected

Remove all power. Measure the resistance between pins 19 & 20 (SRN & SRP).

Measure directly at the charger IC PU4403.

[Ado02]

Re: Acer SF314-41 battery not detected

Remove all power. Measure the resistance between pins 19 & 20 (SRN & SRP).

Measure directly at the charger IC PU4403.

21.0 ohm

[mon2]

Re: Acer SF314-41 battery not detected

The current loop circuit resistance is ok.

Fault may be with the 2*DCin mosfets. Remove all power. Measure the resistance across each of the DCin mosfets (often the 2nd one can be defective).

Measure:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Post each measurement.

[Ado02]

Re: Acer SF314-41 battery not detected

PU4408

1-2-3 & 5-6-7-8 / 4.7 Mohms
1-2-4 & 4 / 3.78 Mohms
4 & 5-6-7-8 / 6.10 Mohms

PU4401

1-2-3 & 5-6-7-8 / 4.9 Mohms
1-2-4 & 4 / 3.78 Mohms
4 & 5-6-7-8 /5.72 Mohms

[Ado02]

Re: Acer SF314-41 battery not detected

SOLVED:

Ordered another brand-new battery and this time everything works as it should.