[engolling]

Hi Stephan,
I let the TX run on UPS, after an hour no more power at the output. It starts again after i plug a 12V 2A PSU.
I have 8.2V at B-B+ (with or without PSU), only 3V at P-P+ ?
Is the TP5100 faulty ?

At least, the protection circuit seems to be open. Maybe you can remove and insert the 18650 Cells again and check if something changes.
Because it the switches are closed you would see 8.2V at P+ and P-

What that means for the TP5100 I can not tell you at the moment but maybe it trys to bring up the battery voltage with the "precharge" current again and that why it seems to be faulty.