Dead Thinkpad E15, hissing noise from BQ25710

[badcappo]

Hello there, got a Thinkpad E15 on the bench, almost no vital signs. Only things: Power button white LED flashes several times when USB-PD gets connected (number of flashes varies from three up to twelve times, sometimes no reaction at all). Battery charge indicator LED stays orange. Most interesting is hissing / whining sound from Battery Charge Controller IC BQ25710 on the keyboard side of the main pcb. Board fuses tested and intact, no shorts found so far. BQ25710 is also the only thing on the board to become warm in thermal image (below 70 °C). Thanks for any hint.

[kotel studios]

That would suggest the BQ25710 being bad. Check if all the input/output voltages are correct. And you might also see if the laptop tries to power on without that chip. Not sure if it's not gonna damage anything if it's not there....

[Sametbey]

If the charge light is on, this indicates that the Bq24710 and IO circuit are working. The 3.3v line is intact. BIOS can be tried.

[kotel studios]

Yeah but I don't think BQ25710 should get that hot. I am not a specialist, but 70C doesn't sit quite right with me....

[Sametbey]

There is a diagram on the forum. The charging chip and other operating voltages should be measured.

[badcappo]

Thanks for the input. The hissing sound still makes me wonder, has anyone experienced this? It sounds exactly (!) like these small flash discharges when you're touching a plasma globe and it comes right out of the chip (pressing it gently with a screwdriver has no effect).

[ajgae]

Ive heard hissing sounds from bad components before, specifically I once saw a board that had soldered-on RAM and one of the RAM chips was hissing impressively loudly and getting incredibly hot. Covering it with IPA revealed a hot spot in a corner of the chip which I figured just meant the chip was dead. If a mosfet is hissing I can't imagine it can be healthy

[badcappo]

Yeah, might there be some kind of a spark discharge happening inside the chip? This could also explain the hot surface temperature I assume (?). It does sound like these rather new plasma arc lighters...100% the same hissing noise but way more subtle (I have compared it next to each other).

[Assembler]

i have also a lenovo ideapad flex 5 with the same BQchip.. itis hissing for 3 seconds whne the power charger is connected... 70° C... i replaced it immediately.. but no changes... do you have found a solution? the laptop is working (the battery is charging ).. the inductor generating the man power line (the one near BQ and the 2 dual mosfets ) is also becoming hot when the battery is connected..
looks like everything is working but this IC at 70 is not ok.. and also the inductor is not ok to became hot.
also i charged the battery ,manually to see if the power consuption is lovering.. butseems that a some point the battery stop increasing voltage. but the A consuption of the laptop stay at 3 A... (this is a 65W .. this is the maximum hat a charger can handle).. when laptop is on. and the battery is lower the power consuption is 4.1A (???) ... with battery charged 3A ... without the battery .. 70/80 ma in idle mode.

[mon2]

The last suggestion is important. A recursive response.

A hissing noise from the BQ25710 battery charger controller is typically caused by piezoelectric vibration in nearby ceramic capacitors or inductors. This occurs when high-frequency switching currents cause the components to expand and contract, producing an audible noise. [1, 2]

Why is it happening?

• Component Vibration: The IC itself rarely makes the noise. Instead, the rapid voltage swings during charging cause surrounding ceramic capacitors and inductors to vibrate at audible frequencies (often 1kHz to 20kHz). [1, 2, 3]
• No-Load / Low-Load Operation: When a battery is removed or is failing (e.g., reads 0V), the switching converter may enter discontinuous or pulse-skipping modes. This causes erratic switching patterns that result in a noticeable buzz or hiss. [1, 2, 3]
• Degraded Capacitors: Over time, the glue securing these components can degrade, amplifying the vibration. [1]

What you can do

1. Check Battery Health: Since faulty batteries (zero voltage or bad cells) can cause the BQ25710 to enter abnormal switching modes, verifying the battery's health is the most critical first step. [1]
2. Dampen the Noise: If the noise is intrusive but the board functions perfectly, you can physically dampen the buzzing components (such as inductors) by applying high-temperature, sensor-safe silicone sealant or electronics-grade hot glue. [1, 2]
3. Inspect the Circuitry: Browse through the Badcaps Hardware Forum for threads discussing similar power management issues on equivalent boards (like ThinkPad E15s) to see if other components are failing in your specific device.

[Assembler]

what is this? IA generated answer? degraded battery? there is not a battery.
silicone to stop buzzing? what??? are you crazy? this is a laptop.. not a catodic TV

Inspect the Circuitry... ah ok.. this is a great suggestion. ahhahahaa (next suggestion can be to DEFRAG the drive)

[mon2]

IA? What is that? It is AI.

Reading helps..

Degraded Capacitors

Yes, this was a (missed joke):

1. Inspect the Circuitry: Browse through the Badcaps Hardware Forum for threads discussing similar power management issues on equivalent boards (like ThinkPad E15s) to see if other components are failing in your specific device.

[Assembler]

IA? What is that? It is AI.

Yes, this was a (missed joke):

1. Inspect the Circuitry: Browse through the Badcaps Hardware Forum for threads discussing similar power management issues on equivalent boards (like ThinkPad E15s) to see if other components are failing in your specific device.

on my native language AI is called IA (Intelligenza artificiale)

(like ThinkPad E15s) yes and i write on this post because is the only one mentioning another lenovo and the BQ25710

btw i will reduce the charging current increasing the value of the power sensing resistor near the swiching supply for the battery.

[john49884]

i have also a lenovo ideapad flex 5 with the same BQchip.. itis hissing for 3 seconds whne the power charger is connected... 70° C... i replaced it immediately.. but no changes...

In my experience, that behavior happens when the output of the chip is shorted or partially shorted by its components. I've seen faulty mosfets produce that. What can you check in circuit? with the laptop on measure the voltage drop across the mosfets of that chip; it must be virtually the same at both sides, if not, replace them.

[john49884]

I forgot to add that I wrote in post #14 is for mosfets acting as a simple switch. For faulty mosfets in a pwm generated voltage it more obvious because they get hot quickly. Ultimately components shorting your chip pads it's what I've seen, with mosfets being the most probable cause but not limited to that. If I remember correctly I saw a soft start shorted capacitor producing a high pitched noise in a VRM.

[mitchw]

If the output inductor (choke) is shorted internally, there could also be hissing and some sound emitted.
Once had a MacBook board with the similar thing, it was working, but there was always an annoying buzz. Culprit was partially shorted output inductor on PP3V42_G3H line. If I remember correctly, the output voltage wasn't exactly spot on too, but a tad low.

Capacitors could also produce annoying sounds, especially ceramic caps.
Chip shouldn't do this on its own, at least I think so.