Battery not charging in ASUS G532LWS Motherboard -> BQ24780S

[cope]

When you 'drained' the battery - did the battery percentage ever change? Are you able to extract the battery serial #, etc. on Windows ? Arduino tools ? Just want to confirm that the SMBUS / I2C interface is not defective. You can also remove all power -> meter in DIODE mode -> measure the battery connector pins on the logic board and post each diode mode check. We are checking if the ESD diodes are shunted and may be causing goofy readings by the host SMBUS controller.

Yes, I ran the laptop on battery only, planning to start charging it again at 10%. But, I got distracted by work and it was shut off when I looked back over. When I looked away it was at ~13%. Plugged it in and started back up and the level showed 5%.

Let me see what information windows has about it, I assume in device manager on the battery itself?

[cope]

mon2 I have access to a lot of properties in the driver details tab but I am not sure where the serial number is in these properties. It is a generic battery from Amazon and it is being recognized as Microsoft ACPI-Compliant Control Method Battery in windows.

Let me know whatever you need from there. I don't have an arduino which I think is necessary to use the tools right? It's not something I can just install on windows and read I2C information I'm thinking.

As far as the pin readings go, do you want all pin combos in both directions? data/clk/+/-?

[mon2]

No, not the driver details but the details of the battery itself. There is a BMS (battery management system) board buried inside of the battery pack. This BMS communicates with the logic board using the SCL / SDA lines that are present on the battery connector. This is common to laptop designs. If either the SCL or SDA line is shunted, the communication and charging will halt. Wondering if you are facing just a bad battery pack from Amazon. Personally have had good luck with Amazon for macbook battery packs but we like to stay with the most positive reviewed products.

When you charge with the logic board -> what is the battery pack voltage on the connector? This is the charger created voltage.

What voltage do you use to charge it with an external power supply?

[cope]

No, not the driver details but the details of the battery itself. There is a BMS (battery management system) board buried inside of the battery pack. This BMS communicates with the logic board using the SCL / SDA lines that are present on the battery connector. This is common to laptop designs. If either the SCL or SDA line is shunted, the communication and charging will halt. Wondering if you are facing just a bad battery pack from Amazon. Personally have had good luck with Amazon for macbook battery packs but we like to stay with the most positive reviewed products.

When you charge with the logic board -> what is the battery pack voltage on the connector? This is the charger created voltage.

What voltage do you use to charge it with an external power supply?

I was seeing a boost to about 16.8V-17.2V when the adapter was plugged in while charging yesterday. This was when the battery was outputting about 15V to the coil (at 7% charge). These numbers are from memory and may be a bit rough because I've had to remember a lot of numbers lately.

I am charging with my bench supply limits set at 17V, 0.5 amps and the battery seems to pull .5 amps at 15.5V.

This is my second Amazon battery, the last one had a blown fuse and would not take a charge with my bench supply. I went with a different seller this time and it seemed to be working OK until this.

So you just want me to do the diode mode test on data and clk then? I will work on that.

[cope]

mon2 Sorry, did you mean the connector on the motherboard or on the battery for the diode test of data/clk lines?

[mon2]

Test in diode mode and check on the battery connector that is soldered on the logic board. Do not have the battery connected. The logic should feature some TVS ESD diodes on the connector. These diodes are present to prevent ESD damage to the mated boards. Check each pin and post the full list. One end will be the B+ group (often 2-3 pins); other end will be ground.

[cope]

mon2 Diode mode on BATCON pin voltage readings

Red probe +
Black probe - 2.962V
Black probe data 0L
Black probe clk 0L
Red probe -
Black probe + 0.51V
Black probe data 0.49V
Black probe clk 0.55V
Red probe clk
Black probe + 2.64V
Black probe - 2.49V
Black probe data 2.55V
Red probe data
Black probe + 2.64V
Black probe - 2.49V
Black probe clk 2.56V

[mon2]

To clarify the above table, meter in DIODE mode. Keep the red meter probe on ground (metal shield is ok).

Black onto the battery connector pins. Label each pin # so they are easy to follow.

See attached. The circled pins are the most of interest = SMBUS lines.

[cope]

mon2 While I had it powered down I touched up the solder on pins 22-28 of the BQ chip with an iron (I'm thinking maybe I didn't do a great job seating that corner of the chip). The battery is charging again.

If I see intermittent weird behavior I will report back but I'm allowing it to charge up right now.

Maybe I was barely making contact yesterday and something flexed?

[cope]

mon2 OK, status update.

It charged to 100% and stopped charging as expected.

I ran the laptop on battery for about 4-5 hours so the battery life seems to be good.

It shut down from lack of power at 6-7% reported battery life remaining according to Windows.

I plugged it back in and I'm seeing the same behavior... boots into windows, windows says it is charging, but it is not going up. So, it seems like when the battery is low the charging circuit will not resume charging.

I'm a little confused as to why touching up the BQ chip has fixed this twice. Unless something about heating the BQ chip slightly is reducing a resistance somewhere (or something like that) and getting current to start flowing to the battery. 🤔

I am curious if boosting the battery with my bench supply to something like 20% would restore the functionality without the soldering iron this time.

[mon2]

Tie ILIM pin directly to +3v3. Test again.

[cope]

Tie ILIM pin directly to +3v3. Test again.

Hmm, I've never done that before so I may need a little help so I don't goof something up. I have a resistor that separates the ILIM circuit from +3VA, should I just bridge that? Attaching a zoomed in BV with the resistor circled and its location relative to the ILIM pin.

[mon2]

Yes, bridge PR8913.

[cope]

Yes, bridge PR8913.

Hmm, just an observation but the schematic rates PR8913 at 120kohms but it measures 89kohms. Is that a significant enough difference to cause an issue?

Also PR8914 schematic value is 68kohms but it measures 57.6 kohms, less of a difference but just so you have the information.

[mon2]

Earlier, you measured the voltage at the junction for ILIM. The voltage was correct for ILIM so PR8913 is 120k. It is probably measuring lower since it is in circuit. According to the datasheet for the charger, if ILIM is 2V or higher, you are instructing the charger IC to support the charging with max current.

[cope]

Earlier, you measured the voltage at the junction for ILIM. The voltage was correct for ILIM so PR8913 is 120k. It is probably measuring lower since it is in circuit. According to the datasheet for the charger, if ILIM is 2V or higher, you are instructing the charger IC to support the charging with max current.

I will work on testing as you mentioned.

I'm learning a ton here so I have lots of questions, but I know you're busy helping lots of people so telling me you are too busy to answer is also fine.

It just clicked that the circuit we are looking at is a voltage divider (and the same you were testing with the calculator you sent earlier). Its purpose is to step down +3.3V to the ILIM voltage required.

In the calculator diagram:
PR8913 is R1
PR8914 is R2
Vout is the line going to ILIM (and the other Vout would be GND? I'm less sure about that part)
+3VA is V1

That being said, this input voltage will never change unless either the resistance of one of these resistors change or +3VA changes, correct? I don't understand how it will ever exceed 2V and enable charging.

I'm also not sure what PC8911 does, except maybe stabilize the voltage here.

[mon2]

PR8913 is the high side resistor and imposes a resistance of 120k = 120,000 ohms. Higher the resistance, the lower the voltage will be. By soldering this resistor as a short, you will have 0 ohms here so 3v3 will reach ILIM > 2 volts = max current will be supported by the charging circuit. According to the datasheet, when this pin is strapped to be > 2 volts, even the software registers for charging are bypassed and peak (safe) current is applied for charging. Will be interesting to hear of the progress but it is logical that it should work for your case.

[cope]

PR8913 is the high side resistor and imposes a resistance of 120k = 120,000 ohms. Higher the resistance, the lower the voltage will be. By soldering this resistor as a short, you will have 0 ohms here so 3v3 will reach ILIM > 2 volts = max current will be supported by the charging circuit. According to the datasheet, when this pin is strapped to be > 2 volts, even the software registers for charging are bypassed and peak (safe) current is applied for charging. Will be interesting to hear of the progress but it is logical that it should work for your case.

Hi mon2, I was out of town for the summer and had to leave this repair sitting on my desk for a few months. I'm back now and I've tied 3.3V to ILIM by shorting PR8913. The battery is still not charging when the charger is plugged, and the charging coil on the motherboard seems to be sitting at the current battery voltage and not increasing as expected to start charging the battery.

Is there anything else I can check as far as prerequisites for charging go?