Milan TDI

I still have some worries about battery discharging when car not running. My voltmeter indicates:
- when engine is running: 13 V constant (OK)
- when ignition on: between 10 and 11 (seems to depend also on how many days car has not been used); after a while, even if I do not start, the reading tends to go to 12 V.
Are these readings normal?

paulroad

What are you hooking your meter to?

Milan TDI

It's the voltmeter in the dash

ReWa

Hi,
I have taken some measurements with a Dig. VoltMeter, this because the In-dash one is not that accurate. And since my allroad is pretty much comparable with yours (2.5 TDI) I guess that the readings should be more or less equal. I measuered it at the cigarette lighter plug, and also give you the In-dash meter results:

Ignition off: DVM: 12.50V In-dash: 12V
Ignition on: DVM: 12.28V In-dash: 12V
During starting: DVM: 10.41V In-dash 10V
Engine running for 1 minute DVM: 14.01V In-dash: 14V

Now your values are lower, this could be caused by an In-dash meter not giving real values, it is more an indicator then a measuring device, or because there is something wrong.
The behavior that the battery voltage gets higher after ignition on for a while might indicate a bad battery condition. Because after switching ignition on several things happen, Automatic valves are set up for the airconditioning, interior lights come on and of, Radio might switch on, all computer controllers like ECU and so on start up.
However during ignition-on also the glowplug(s) (correct English?) is / are heated, which draws much current Now here in NL it is warm (+12 C)so the glow-time is currently less then a second. If in your case the glow-time is longer then it could be normal that the voltage drops to 10 / 11V.

I would suggest to find a better measuring device and measure "real" values.
During charging the battery (running engine) the voltage should be 14V or higher. Especially under normal driving conditions for more then 15 minutes or so. If it actualy is 13V someting is wrong , and the battery would be most suspected.
This all of course in my opinion.
Success!

Milan TDI

Makes sense.
The battery is new though (they just changed it).
It may be that when ignition on the reading is 10-11 during "glowing", then goes to 12.
I will check that.
I also need to check the "glowtimes", because mine seems longer (a few seconds). Outside temp here in Milan is now 12°, rarely goes below 0°, and my car is parked in a garage (not heated but protected, I guess temp is not lower than 5-8° even in winter)