Can I use VCDS to check the alternator / battery charging OK ?

[headache56]

I have the latest VCDS and the Ross-Tech cable.

My car battery is weak and I probably need a new battery but, just to check beforehand, I wonder if I VCDS has any functionality to check if the alternator output / battery charging is satisfactory ?

I have an Audi A4 late 2008 1.8t (B9).

[headache56]

Er fat finger syndrome, that's a B8

[bearthebruce]

VCDS is a tool that allows the user to communicate with the modules in the car. In that regard, VCDS has no ability to monitor systems. It can only pull information that is monitored by the control module built into the model platform.

The B8 A4 has a lot of monitoring capability. I am certain that you can view live measuring values that would display the "system" voltage. Whether or not that will actually help to determine if the alternator is bad, may depend on which module does the monitoring.

I know my answer is not quite what you wanted to hear. If you are asking if there is a parameter that tells that the alternator is functioning properly, I do not recall seeing any such parameter. Live voltage value on many modules - yes. Good alternator? Probably not.

In an alternator test, it should always be tested under load. I would be looking to see if you had a big voltage drop when lots of accessories are turned on. By big, I'm talking about a 2 volt or more drop in system voltage. If so, then I would suspect a blown diode in the alternator.

[headache56]

Bruce, thank you, most helpful.

Measuring block 1 gives me a steady 14v. Perhaps more relevant, to the charging circuit, I connected a multi-meter (in series) across the battery. This gave me 14.2v at tickover with no real load and it dropped only to 13.7v with aircon, fan blower, heated rear screen and radio on. So this is all good. Thanks for the diode tip, in case of need. Maybe its just the cold weather but I will keep an eye on it.

On passing, looking at the web size www.audizine.com , I saw a poster who had posted a screen print showing VCDS release 10.6.0 -> 19-CAN Gateway --> measuring blocks -> Basic Settings -> measuring blocks 18, 9, 20 which showed measurements like Battery state of charge, battery state, battery aging, internal battery resistance, battery capacity, quiescent voltage. Should I be able to see similar measuring blocks for my Audi A4 (B8) using my later version of VCDS (v 11.x) ?

[headache56]

Bruce,

My final post on this -> I found all the measuring blocks 18,19 & 20 OK.

After 12 hours of charging via a battery charger last night, Measuring Block Group 19 shows an unimpressive 59% battery charge but - even worse - measuring block Group 20 Battery Capacity Available (actual/available) shows only 12Ah. This compares to 53Ah that I saw on the other poster's sample screen print. So I will buy a new battery ASAP.

Cheers, Headache

[a8 tech]

see here no need to visit those lesser sites lol as most of the detail is from here anyway
https://www.vwaudiforum.co.uk/forum/s...attery+manager

post #28

[Kategolf]

vw mk5 golf. my intercooler has blown of and oil is coming out of it, i tryd to clip it back on but clip seems to be broke, there is also no power out of car, does this mean the turbo has gone

[a8 tech]

no replace the pipe and clip also possible inter cooler housing damaged

there can be at least 1 litre of oil running around the system so unless there is major oil repair as you find and make sure there is no excess oil in the inlet manifold but also if possible feel the free play on the turbine intake side for possible wear

[bearthebruce]

To the OP (Headache):

Should read before I type... glad to see you have found your answers.....