angrypengu

One surprising upside of the 48V mild hybrid system is the 12V battery is basically always at 100%. That should help prolong the life of the battery (12V).

Torque450

Well, not in my experience I'm afraid. Bought car at 3 years old, took it back to Audi after 2 weeks as not holding charge, 48v system fully checked over 4 days, 12v battery needed replacing.

angrypengu

Damn. That's not good. Those batteries aren't cheap either at like $700 CAD last I checked. Did they use the medtronic tester on the battery to confirm it btw?

I had a very low SOC 12V battery that I thought was dead and post medtronic testing the SOC basically 'reset' and the battery has been healthy since. Yes, I know this is a ludicrous comment to make but it's what happened!

Torque450

I was paranoid about the 48v/BSG at the time, so insisted they check everything. They replaced the battery after overnight charging and testing and then ran the car and checked it over the next two days to check the 48v/12v interaction.

Anthony Sarrouf

I was about to replace my battery when I read in the repair manual that the 48V system needs to be degenerated first. I took it to the dealer, paid $600, and asked them how did they do it and said they unplug the cables and replace it lol. Now it could be that the service tech who spoke with me wasn't aware of the procedure. Before reading the manual, I removed the cables (very difficult) to reset the car because it was acting up as all cars do when the battery is almost dead. Nothing was damaged but I'd recommend to still get it done the right way. Also, registering the new battery is a must so you'll need professional software regardless