My iMiev started to interrupt charging because of a BMS error.
I brought it to the garage, hoping they could just fix the problem, like one would expect as a customer. Because the car has a battery pack still using the old LEV50 cells an not the new LEV50N, Mitsubishi does not deliver any replacement parts.
The garage did quite a good job diagnosing the problem, they saw problems on the cell voltage sensor of BMU06 and the error code P1A7B.
With this information I've started to research for myself. Hoping to be able to fix the problem.
I've attached all the cables of the battery to the car, except the orange high voltage cables. This allowed to test the BMU and observe the cell voltages using OVMS again.
Be aware, this triggered an airbag warning, wich needs to be reset by the garage. The warning is due to powering the car (attach the 12V battery) with disconnected airbags. The airbags are disconnected because I've taken out the drivers seat to gain access to the HV plug of the battery.
I've actually had the plan to replace the LTC6802, but unfortunately it had a very small pin pitch and I am not so good at soldering. That's why I've odered some secondhand BMU PCBs found on Ebay. They unfortunately did not have the correct ID (01 and 12, I need 06) that's why I've decided to move the EEPROM from the original PCB to a new one.
On this occasion I've pulled a dump of each EEPROM using an Minipro EEPROM reader. See the *.srec files in the project documentation.
It would be easiest to use a car lift to take down the battery, unfortunately I don't have access to one. So I've helped myself using stacked euro pallets and a forklift. The Mitsubishi dismantiling guide I've found on the internet also helped a lot to take down the battery. It's quite some hours of work.
First I've installed an OVMS (https://www.openvehicles.com ), which has a great diagnostic interface for the BMS. There, I could see the voltages of all 4 cells of BMU6 floating around, having values clearly out of any sensible range. If this happens too long the BMU will issue an error and hence charging will be stpped.
Having researched online I've found others also have similar problems. There are some good threads in forums: