MrFlibble wrote: ↑Sun Jun 09, 2024 10:42 am With your knowledge on reverse engineering of ECUs, is it likely that there is an EEPROM on either J840 or J497 where the batterty capacity is encoded?

Yes, 90% Chance its a simple external eeprom on pcba.
10% Chance its internal one in the CPU used

The link you posted has some interesting info:

Address 8C: Hybrid Battery (J840) Labels: None
Part No SW: 5GE 915 225 B HW: 5GE 915 225 B
Component: K8C 005 0400
Serial number: 03012001013888
Coding: 000000000000000000000000000000000000000000000000000000000000
Shop #: WSC 00000 000 00000 ...

Hallo
I did not check your alternative Battery Cells.
I am preparing to Convert my T5.2 to E using E-Golf and E-Up Parts.
So i started in gathering Data.
I am doing Reverse engeneering VW ECU´s for some Years ....

Regarding your Capacy Change.
I guess the BMS is responsible for Broadcasting the ...