Battery problem

[Fion]

Hi Bros,
My Macan GTS battery installed, Varta AGM G14. Reads 12.8V before engine ignites, 13.0V from idle to 2500rpm. Voltage only increases when braking from 13.0V to 14.4V, quickly lowers when brake is released. Anyone has idea what's going on? Thanks!

[porscot]

Hi, and welcome.

Other than the voltage varying you don't mention any problems that go with it. It reads like you car starts fine and I assume runs as expected.

If under warranty and there are issues, simplest just to give it to your local OPC to review.

Regards
Graeme

[wilko]

Completely normal.
Battery only charges when braking, unless it’s low, in which case it charges all the time.
All to do with reducing parasitic load on the engines to reduce emissions.

[Fion]

Thanks Graeme & Wilko,
It all happened last week that, all of a sudden when driving at 20mph, multiple warning lights shot up, ABS, traction control, parking brake, gear fault( yellow possible no R and then red), engine control contact dealer. So I went to change the battery, the next day all signs gone on their own.

[RickZ]

Mine reads 14 volts all the time I'm driving it. It's my understanding that to maintain a 12 volt lead acid battery at full capacity it should be charged at a minimum of 13.8 volts therefore charging at 13 volts won't maintain full capacity amp/hour rating. The knock on affect would be shorter battery life due to under charging and quicker loss of charge during multiple starter cranks and quicker loss of charge during periods when a car isn't used.