Amme

How do I know if my battery is healthy?
I went in to vehicle data and the car had under 12 volt when cold, haven’t started over night. The car started fine and went to 14,8 volt
the IB was high over 30 A but as the car got warmer the IB got lower. It went as low as 1A

how much should it be when coasting on the highway?

Andy74

How do you get this information on your dashboard?

CA_E55

Sounds about right - in cold temperatures the battery voltage is lower, the charging on start up looks good, and as the battery charge is reaching its max, the current is gradually lowered. But the health of the battery can really only be tested with a battery tester, either a load tester or with an electronic tester measuring the internal resistance of the battery.

Amme

first one in the menu is vehicle data

Amme

Thanks. I’ve read that newer Merc’s have smart charging and the alternator charges up to 75%. The rest has to come from regenerating, if it’s braking or coasting I don’t know.
I just want to know if I need to change the main battery or auxiliary battery. Have had small problems like the start/stop not working and the rear diff inoperative message(when the message is on dash the car won’t start, usually goes away on its own)

Andy74

Great thanks.

stockbmw

Grab a multimeter and check the voltage directly from your battery. When I checked mine, it read 12.6 from battery and checking the car using workshop menu, it decreased to 12.2 in span of 30seconds.

I regularly top off my battery every month using a battery maintainer and check the voltage for both battery and in car. And all the time, I get stump when get lower readings in car.

4.20.20 Corona update :
Battery maintainer on for past few days because car was infected. Voltage meter read 12.6 and but when I hopped into the car, workshop menu again shat me with 12.3

Senecat

Great, now YOU'RE infected.

You might wanna get a couple more boosters, stat.