Thread: Battery and Alternator

You need a battery tester to check the battery. However, your short drive each day is not helping, so expect the battery to only last two to three years. Also, once the car has travelled around 150,000km it's time to consider replacing the alternator. They tend to go at around 170,000km. Your use of the car translates as arduous conditions, so you can expect other stuff like discs and pads and fluids to need regular replacing. To this end, I hope you are replacing the engine oil and filter every 10,000km, gearbox at 90,000 and every 40,000 thereafter, diffs and transfer case every 40,000 and brake fluid every two or so years.

Short trips kills these cars and most diesels imho.

Need to go for a long drive and "give it the berries" as they say.

The smart alternator in these cars only put out the current that is being asked for, so short trips does not allow them to top up the battery sufficiently, more than likely the cars electronics are being run off the battery, and the alternator just (barely) maintains a float charge on the baytery.

What’s the battery specifications for D4 sdv6?

Check main battery voltage on IID tool.

Car running: 13.8v to 14V
Not running: 12.5v
Starting: drop to 9.8V in the process

From those data, can you tell whether the battery or alternator needs replacing? Thanks

Alternator is fine. Get a new battery

Originally Posted by fourteen8

Check main battery voltage on IID tool.

Car running: 13.8v to 14V
Not running: 12.5v
Starting: drop to 9.8V in the process

From those data, can you tell whether the battery or alternator needs replacing? Thanks

When voltage drop below 10v at start up, battery is done for