Customer:
I plugged in USB with a LIPO attached and got smoke from the MCP73831T component. The device still seems to work OK on USB but what could have gone wrong? Can I fix it?
Originally submitted via email support on 20 October 2023. Migrated to the forum for community visibility.
Soldered Support:
The MCP73831T is a battery charger used on Inkplate. It’s hard to diagnose specifically without examining the device, but if smoke came out of it, the charger is damaged.
Inkplate has its own internal IC for charging and powering the device via the dedicated battery connector (Standard JST-PH-2mm connector). We’d recommend using that connector rather than connecting USB and LIPO simultaneously in other ways.
Without knowing exactly what happened, I can’t guarantee the fault was only on the MCP73831T. Test all Inkplate’s features through examples and see if things work OK.
Customer:
The MCP73831T is actually the charge controller for the LIPO, located just below the 2-pin connector where we plugged the battery in. It smoked as soon as we attached the USB cable. Can we learn more about what caused this?
Attachment omitted in migration: image001.jpg
Attachment omitted in migration: image005.png
Attachment omitted in migration: image002.jpg
Attachment omitted in migration: MCP73831-Family-Data-Sheet-DS20001984H.pdf
Soldered Support:
Since smoke came out of the IC, the charger is damaged.
Did Inkplate work on the battery before the smoke? Can you provide more information about the battery (voltage, capacity, photo of the connector, and how you connected it)?
Customer:
We previously tried a 3.7V 500mAh LIPO battery which didn’t work but produced no smoke. The battery that caused the smoke is an EEMB LP103454-PCM-LD 3.7V 2000mAh with a JST-PHR-02 connector. We verified polarity and battery voltage.
We plugged it into the board without a power source connected initially.
Now the device is dead. The power LED comes on but nothing appears on the display, even when flashing with code that previously ran. We want to know what caused it so we can avoid this in the future.
Attachment omitted in migration: image001.png
Attachment omitted in migration: image002.png
Soldered Support:
If your battery has the polarity shown in the picture, you have the wrong polarity for the battery connector. That damaged the battery charger.
Measure the voltage on the 3V3 and VIN pins when the USB cable is connected and Inkplate is turned on. The charger may have caused a short between GND and USB, which is why Inkplate doesn’t work. Because of the wrong polarity, something else may have been damaged on the board too.
Customer:
Can we be completely sure about the polarity? All the batteries we have use the same connector and sense.
Attachment omitted in migration: image006.jpg
Attachment omitted in migration: image005.png
Attachment omitted in migration: image003.jpg
Attachment omitted in migration: image001.jpg
Attachment omitted in migration: image002.jpg
Attachment omitted in migration: image004.png
Attachment omitted in migration: image007.jpg
Attachment omitted in migration: image008.png
Soldered Support:
Your battery has the wrong polarity. For Inkplate you need connector polarity as shown in the picture.
The charger was damaged for sure and probably something else. You can remove the charger IC from the board with a soldering iron, but be careful when heating the board because the e-paper panel can be damaged if heated. After removing the charger IC you can try to turn on the Inkplate - if it works then only the charger was damaged.
Attachment omitted in migration: IMG_20231024_122509.jpg
Attachment omitted in migration: IMG_20231024_122456.jpg
Attachment omitted in migration: IMG_20231024_122338.jpg