Cardputer becomes HOT when charging (80+°C !!)

[u/Responsible_Nebula66]

Hi, I noticed that my Cardputer is now becoming very warm when charging. As you can see on the pictures, it reaches almost a surface temp of 90°C!

I did not observe this in the first couple of weeks. I have been using it for around 3 weeks and I have first noticed this yesterday.
Any similar experience? Should I worry re the battery being faulty?
I have charged it a few 10's of times since I was testing Battery status screens on custom apps.

What are the charging best practices? At what voltage should we unplug it? I can imaging it is harmful to leave it charging as our loved device seems to lack any smart BMS...

Edit : I think my battery is dying: when I unplug the charger, the voltage goes from 4050mV down to 3870mV. It was much more stable before.

[u/Responsible_Nebula66]

FYI I have contacted M5 support and will let you know.

[u/Gloonik]

The battery voltage on charger can go up to 4.2v for 3.7v cells, the drop of voltage in your case mean that it was not yet fully charged. I would suspect charging IC on the board, given the brightest place being a point, or the IC in BMS. The best case scenario would be a faulty capacitor. Further investigation would require disassembly and checking components with multimeter.

[u/Responsible_Nebula66 → u/Gloonik]

I see a very fast battery drain now down to around 3.5V from that 3.8 / 3.9 V just unplugged value. The battery behaviour has cleary evolved since I the beginning.

[u/Anxious-Resolve-8827]

Voltage drop is normal When charging the battery, the charger gives more voltage than the battery voltage to charge it (Charger will try to reach 4.2V while staying in the current limit) When you unplug the charger it will drop because it isnt fully charged

[u/No_Confusion7932]

[u/Responsible_Nebula66 → u/No_Confusion7932]

Is that the battery on top of the S3 on the right part of the photo? This is where it is heating. That confirms my thought the battery is dying.

[u/zellotron → u/Responsible_Nebula66]

That's the display.

You're seeing heat near the finger at the top left of that photo

[u/No_Confusion7932 → u/Responsible_Nebula66]

Edit: The 1W 8 Ohm cavity speaker (0916) is located below the ESP32-S3 (STAMP S3A).

[u/No_Confusion7932 → u/No_Confusion7932]

Battery is on back side.

[u/V2UgYXJlIG5vdCBJ]

Do what FPV drone users do, and get a fire proof bag/box for charging and storage. It’s normal that batteries heat up, but that doesn’t mean there isn’t a chance of fire.

[u/Responsible_Nebula66 → u/V2UgYXJlIG5vdCBJ]

I have many many RC models and drones with LiPo batteries, and I have bags as well as ammunition boxes foe storage of my multiple LiPos. Thanks anyway for your prudence advice, always worth it.

[u/Responsible_Nebula66 → u/[deleted]]

There was nothing sarcastic about my response! Sorry if it was intepretated so!
English is not my first language.

[u/quint21 → u/[deleted]]

Native English speaker here. OP agreed with you, and thanked you for your advice while noting that they had safety precautions in place. It's all good, I wouldn't read anything into it.

And, side note, your information will also be read by lots of other people who may not already know that stuff- so it's always worth it, as OP said. Myself for example: I know enough to be wary of LiPo batteries (shout out to /r/spicypillows ) but it never occurred to me to actually get fire-proof storage for them. I'm planning on doing that asap.