MTV10

Driving home tonight I got an orange battery light on the dash. Once home, I restarted the car and it went away, only to drive down the block and have it come back. Went through the Dyno Mode process to see Vehicle Data and got the following readings...

Car at idle:

• UB: 11.6V
• IB: -52.0 A

I understand voltage should read 14.7. Car also seems to be pulling a lot of current at -52A. I'm wondering if this is the battery not holding the charge or the alternator not charging. Checked the belts and everything is nice and tight.

Any input it appreciated. Have a road trip planned in 2 days, so hoping battery is the fix...

Critter

How old is the battery, Try to charge the battery overnight voltage should be 12.5 to 12.7 unloaded
If you want to test the battery turn on the aux in the key and turn on the headlights heater and seat heaters for 2 or 3 min now check the voltage if it is below 12.0 the battery is toast
If battery checks out start the car the voltage should be 14.2-14.4volts
Could be the regulator inside of the alternator which causes some fuss, or if the battery is old ( 5-7 years ) also load test is also good at a battery shop
Or replace the alternator all together if the mileage of the car is over 100000 km
Hope this is helpful
But if you do put in a battery and call it a good day monitor the voltage when driving it should be 14.2 volts all the time

Funkwagen

Voltage should definitely be above 13v when the car is running. Alternator or voltage regulator on the back of alternator has probably died.My case, it was the alternator entirely

WIN ER

The current drain is too high (IB:-52.0 A). I have it around -11A/-12A with engine off (radio off, heaters/coolers off).
With the engine running it should be positive..

SROC276

possibly alternator dying if not battery. Similar happened to me until it fully died and could not start car.

MTV10

Old thread... but yes it was alternator that required replacing.

bennyplunkett

How much did it cost to fix?

hachiroku

i had similar issue....i replaced the voltage regulator. it was 90 bucks? i'd have to check to be sure. very easy to replace from under the vehicle.

wannawagon

Seems weird

I have put new brushes in the old Valeo (very cheap). If you still have the old one see if that’s issue.

CaliBenzDriver

Diagnose Voltage / Amp before pegging everything on alternator or battery... it will come right back 3Mo later!

The silent killer is the poor Engine-Chassis GND strap that glitched the snuts out of overheated electronics.

Just don't jump blindly to conclusion. This is the best German engineering - Go the extra mile when it is your own toy kit.

ECU can be in on voltage swings below 12.0. What do you ecpect: this is way more fun than a Toyota!