My auto Stop/Start hasn't worked for a while now ( months ).

I tested the battery and found it to be around 12.2 volts so bought a new one today. Much to my surprise the auto Stop/Start worked again right away, but just for 1 short drive, now it's back to not working again.

Any ideas?

 

What model details?

 

If you haven't already,
I do know you have to re-register the battery to let the vehicle and battery management system know that the battery has been replaced because it could be still thinking the old battery is still in place if you still haven't registered it yet. You will need an OBD-2 port scan tool that has an battery registration feature to do it.

 

I had this happen to me on a different vehicle, turned out the the new battery was bad. They replaced it & no problems since.

 

What model details?

 

Apologies for the delay.

I fixed this by putting the new battery on a charger overnight then reconnecting it once it was fully charged. Everything has been working correctly since. I suppose the new battery I bought wasn't fully charged.

Interestingly enough I did not have to do anything with the BMS and registering the new battery, never had any errors and have driven about 400 miles since. Everything seems to be good.