[Cyan488]

As an electronics designer myself, I would find it hard to trust the AliExpress board.

Without the design files, running a failure modes and effects analysis on the board is difficult.

There's also no guarantee that each board you get is built identically. Some parts or the whole design could be changed between orders.

If I was designing a power bank board professionally, I'd be putting it through the ringer - environmental, mechanical, component level short circuit, load short circuit, load power injection, input over-voltage, input transient, RFI/EMI susceptibility, etc. Do you trust that all that has been done on a board that is representative of what you've received?

[Panzer04]

There's a difference between acceptable standards for a truly professional product that you'd have to certify and hobbyist stuff.

Beyond short circuit/overcurrent, overtemp, over voltage, under voltage protections, what else would be necessary to ensure safe usage of the cells from an electrical perspective? Ie. What additional protections would a batter management circuit need to be safe in normal circumstances?

[exmadscientist]

JEITA profile compliant chargers require temperature monitoring (usually a 10k NTC thermistor). This is the third (yellow) wire coming out of a typical protected cell.

Many people also like to have fuel gauging but that isn't required.

[knotimpressed]

Definitely agreed on the lack of consistency between orders and even between boards in the same order. I’m doing very low volume for myself and not giving anyone else the banks, so I’m more than happy to check over all the boards for visually obvious issues with a loupe.

As another commenter said, is there anything beyond short circuit/overcurrent for the load side, and undervoltage/overcurrent protection on the cell side that’s crucial for a non professional bank? I’m happy to pop a few boards testing them myself.