Hi

My car is eating up 0.3v from the battery and I believe it is the resistance from the internal circuits etc.

I have Varta E39 AGM battery in Mercedes B160. Few days ago I checked the voltage of the battery and it was 12.1v. I removed the battery to charge it and straight away the battery voltage increased to 12.4v. After fully charging and removing the surface charge the voltage was 12.72. As I reconnected the battery in the car, the voltage dropped by 0.3v to 12.42

So is it normal for 0.3v drop when battery is connected in the car? Would you consider the correct voltage when battery is connected or the open circuit voltage is correct ?

Is there something wrong with the battery or something wrong with the car?

Btw so far I had no issues to start the car.

Thanks

Raj

Edited by Raj Kanwal on 20/10/2020 at 05:14