ASUS X555LD Not charging battery after coffee spill

[slightlyviolent]

Issue

- Long time ago, I spilled coffee on my laptop
- The laptop shut down right away and I made the mistake of turning it back on right away
- Laptop runs fine when adapter is plugged in
- Battery does not get charged

What I've Tried

- Replaced battery with new one
- Measured adapter voltage; there's 19V coming in
- Measured voltage at DC jack — 19V present
- Measured the voltage at the battery connector; here are the values:

NET NAME | PIN# | V
BAT CON - 1 - 0.76
BAT CON - 2 - 0.76
SMB0_DAT_CLK_CON - 3 - 3.23
SMB0_DAT_BAT_CON - 4 - 3.22
LDO_V3.3 - 5 - 0
GND - 6/7/8 - 0

Additional Info

I have the boardview files for the motherboard

(See first attachment)

I found some schematics online as well

(See second attachment)

Questions

1. Are those the right values at the battery connector?
2. What should I check next?
3. So far I've only been looking for voltage drops (0V); should I be checking for other things like current flow, resistance, capacitors?
4. Does the battery need only voltage to recharge? Does the battery use both current and voltage to recharge? I know there's a chip inside the battery that determines how the battery should be charged so I'm assuming that chip talks to the charging controller on the board and if that's the case, then I should be looking for correct voltage values only and checking for current flow is unnecessary — is this correct?
5. Should I check for blown fuses, bad caps, or short-circuits?
6. Could it be that the coffee deposits contaminated the area where it was spilled and covered some components/paths? There were only a couple of drops that got onto the board; most of the spill was caught by the plastic protective layer under the keyboard.
7. Should I try a software fix first? I could try reinstalling the battery drivers or booting from a linux live disk and see if that will kickstart the battery into getting charged; maybe there's nothing wrong with the board itself.
8. So based on what I've read, the controller uses the SMBus to talk to the battery; that explains the CLK and DATA pins on the battery connector; what kind of data is the controller sending?

Thank you!

[piernov]

Re: ASUS X555LD Not charging battery after coffee spill

Do a thorough visual inspection of the board to see what could have been damaged.
Did the laptop run from battery after replacing it?

[slightlyviolent]

Re: ASUS X555LD Not charging battery after coffee spill

Hello,
Thank you for your reply. The laptop did run from battery after replacing it but only because the new battery had some charge already. The laptop ran on battery until it was discharged so afterwards I had to keep it connected to AC to have it running. This confirms that it's just the charging chip that is at fault.

I also found more schematics of the laptop (see first attachment)

I found the charging chip in the boardview and it's PU8800 - CHARGE MANAGE IC HPA02196RGRR.

I looked up the part and found its datasheet (see second attachment). There's a section describing the conditions needed to enable charging so my next step is to ensure those conditions are met.

However, before doing that, can you confirm whether those values measured at the battery connector pins sound correct or not? The value for LDO_V3.3 would change from 0V to ~1V if the battery is connected or not; the other values don't change. Is 0.8V at the positive terminal (PIN 1 & 2) enough to charge the battery? I'm assuming not but I'm not sure. How can I check if there's enough current being drawn?

Thanks again!

[mcplslg123]

Re: ASUS X555LD Not charging battery after coffee spill

Check ACDET,ACOK,ACDRV signal on charging IC.

[piernov]

Re: ASUS X555LD Not charging battery after coffee spill

A bit hard to diagnose a charging issue if the battery is completely flat, but let's assume it's not an issue for now. According to the boardview, LDO_V3.3 is connected to the RTC coin cell battery, so if there is no coin cell battery the only thing that could provide a voltage there is the main battery back which is empty. Voltage on pins 1&2 is close to 0 also because the pack is empty, otherwise it would be between 6.8V and 8.2V.
Make sure both DC-in MOSFETs aren't shorted, check resistance between pins ACN/ACP and between pins SRN/SRP of charger IC

[slightlyviolent]

Re: ASUS X555LD Not charging battery after coffee spill

Check ACDET,ACOK,ACDRV signal on charging IC.

Hello,

Thanks for your help. I checked the voltages on those pins:

ACDET - 2.6
ACOK - 2.99
ACDRV - 19.02

Looking at the pins descriptions in the datasheet, these values seem correct.

[petehall347]

Re: ASUS X555LD Not charging battery after coffee spill

did you give it a proper cleaning to get rid of the coffee ?

[slightlyviolent]

Re: ASUS X555LD Not charging battery after coffee spill

A bit hard to diagnose a charging issue if the battery is completely flat, but let's assume it's not an issue for now. According to the boardview, LDO_V3.3 is connected to the RTC coin cell battery, so if there is no coin cell battery the only thing that could provide a voltage there is the main battery back which is empty. Voltage on pins 1&2 is close to 0 also because the pack is empty, otherwise it would be between 6.8V and 8.2V.
Make sure both DC-in MOSFETs aren't shorted, check resistance between pins ACN/ACP and between pins SRN/SRP of charger IC

Hello, thank you for your help. I have a few follow up questions:

1. Which part is the RTC battery?
2. How do I check if the DC-in MOSFETs are shorted?
3. The resistance btw ACN & ACP is very low; my DMM reads 0.3 and this schematic shows that the resistor has a value of 10m. The voltages at these two pins are equal at 18.34V
4. The voltage at pins SRN & SRP is equal at 0.8V. The resistance btw the two pins is ~17.5; the resistor connected to SRN is at 7 and the resistor connected to SRP is at 10. Again, looking at the schematic above, the values for those two resistors seem correct.
5. I am trying to understand the charging circuitry and there's one thing that doesn't really make sense to me: if the first two pins are connected to the battery and they have small values since the battery is low, the third and fourth pin are connected to SMBus, fifth pin to the RTC battery, and the rest to ground, then which pin is responsible for charging the battery?
6. I am starting to suspect that the BIOS chip is responsible for the fault here. The chip's notch has turned white and I remember being told during one of my circuits labs in school that if an IC's notch has turned white, the IC may be busted. So what if the BIOS is not sending the charge command thru SMBus?

Thanks again for your help! I'm sorry it took me a few days to reply; I was away from the mobo and just got access to it again today.

[slightlyviolent]

Re: ASUS X555LD Not charging battery after coffee spill

did you give it a proper cleaning to get rid of the coffee ?

What is the right way of cleaning it? I don't remember exactly what I did (this was back in february) but I used a q-tip with water (?) or isopropyl alcohol on it to wipe the area where the coffee residue was in.

[mcplslg123]

Re: ASUS X555LD Not charging battery after coffee spill

Hello,

Thanks for your help. I checked the voltages on those pins:

ACDET - 2.6
ACOK - 2.99
ACDRV - 19.02

Looking at the pins descriptions in the datasheet, these values seem correct.

Assuming your dc-in mosfets are N channel, ACDRV pin should be 24V.

[slightlyviolent]

Re: ASUS X555LD Not charging battery after coffee spill

Assuming your dc-in mosfets are N channel, ACDRV pin should be 24V.

I agree w you and the datasheet states the same. However, as far as I understand, ACDRV is used to power the system from AC rather than battery and that's working fine; the laptop runs when the adapter is plugged in but the battery does not get charged. The laptop runs on battery too if there's charge in the battery, but since there isn't any, the system turns off as soon as I remove the adapter. If my understanding is wrong, please correct me

Thank you for your reply and help; I appreciate it!

[piernov]

Re: ASUS X555LD Not charging battery after coffee spill

1/ RTC coin cell battery doesn't matter, it's most likely not even present since the main battery pack is non removable.
2/ Check for short between drain/source/gate of both DC-in MOSFETs, they are the MOSFETs between the DC-in jack and the AC_BAT_SYS power rail. I bet the first one is shorted.
3/ & 4/ yes that's fine, values should rather be checked on the boardview though as you never know if they changed something from the reference design.
5/ Battery is charged through the sames lines as it is discharged, like any rechargeable battery.
6/ SPI ROM chip for BIOS is most likely unrelated and no reason for it to be bad.

[slightlyviolent]

Re: ASUS X555LD Not charging battery after coffee spill

2/ Check for short between drain/source/gate of both DC-in MOSFETs, they are the MOSFETs between the DC-in jack and the AC_BAT_SYS power rail. I bet the first one is shorted.

I know this is very old but I haven't forgotten about it. I just checked the DC-in MOSFETs and the first one is indeed shorted - there's a connection btw Drain and Source when OFF. No issues with the second one. I'm assuming the first one went bust by design to prevent further damage to other components. I don't have the tools to replace the part myself so I'm looking for places that can do it. I plan on using this laptop as a home server for Plex so hopefully after this I can finally declutter my main laptop from all the files. Thanks again!

[mcplslg123]

Re: ASUS X555LD Not charging battery after coffee spill

Remember my post#10. You overlooked it assuming nothing wrong since mb was running thru adapter. Your problem was that only. Hopefully, get the mosfet replaced and everything will be fine.