Battery Issues - P0BBD code, voltage variation exceeded

Cells fail.

That’s my theory and I’m sticking to it.

 

P0BBD is described as "The difference between the each battery cells voltage are more than 14.1 V" from before to after the battery contactor is closed. This monitor is only checked if the 12V system is >10.2V, both during charging and ON modes.

P0B29 is triggered when an individual cell is <1.5V, or the difference between the max and the min cell in a battery is more than some threshold (0.52V when ON mode is entered or 0.97V for 5sec) or the SOC is <0% for 5sec.

My uneducated guess is that either 1 cell is going bad, or there is a bad connection from the individual cell to the circuitry that reads the individual cell voltage. In the case of a bad connection, there could be a high resistance from the cell to the sense/balance circuitry, which causes erroneous reading when an individual cell is trying to be balanced. A connection could be good at low temperatures and bad at high temperatures, or bad with vibration, etc.

Regardless, I think the IPU would need repair. I find it unlikely to be a 12V battery issues if no other trouble codes are flagged. All Clarities should still have an active IPU warranty, so I'd suggest going to talk to Honda...