Can vagcom test battery/alternator?

khcomp

Take it into work - they should be able to diagnose it in minutes: Let us know the outcome.
If the battery is significantly damaged, the voltage readings at the terminals may well be lower than the alternator is able to produce: It may well be a faulty alternator, but get the guys at work to check for you.
Although the alternator should theoretically push out around 13 volts at idle, an internal short in the battery may well prevent it doing so (just as some background, a battery is made up of several 'cells', usually six, providing around 2.1v per cell in tip top condition.). This would mean that VAGCOM or a meter across the battery could well indicate a terminal voltage of 11v or less even with a good alternator, as the battery is effectively negating around 2 volts per damaged cell.
re your pictures: Yes, meter set to volts, red to positive, black to negative, but again, it will tell you very little without disconnecting, charging & testing the battery first. It looks like a very old, American made meter, so there's no telling how accurate it would be anyway, but it may give you an indication. Try it with VAGCOM running and see if it gives similar readings - this should at least tell you if it's reading somewhere near.

AdrianC

JustAnotherSaver wrote: »

Ok i've just called through to my mothers & picked up what i think is a multimeter?



Though it doesn't just have a red & black coming from it, it has that 3rd thing whatever it is.



It's pretty old as it was my dads.

So if this is the correct bit of kit, old as it is, do i just leave the wheel set to 'Volt', put the red to pos, black to neg (& what of that 3rd thing that runs off this?) & then read off whatever it says in that middle band for Volts?

And engine running or not for that?

The science museum called. They'd like that, if it wasn't quite so badly-stored-looking.

Frankly, I wouldn't be surprised if that lied like a politician. But it'll probably do the job. When you start the car, and rev it to 2,000rpm or so, you should see the voltage across the battery rise by 15-20% or so.

BeenThroughItAll

JustAnotherSaver wrote: »

Ok i've just called through to my mothers & picked up what i think is a multimeter?



Though it doesn't just have a red & black coming from it, it has that 3rd thing whatever it is.



It's pretty old as it was my dads.

So if this is the correct bit of kit, old as it is, do i just leave the wheel set to 'Volt', put the red to pos, black to neg (& what of that 3rd thing that runs off this?) & then read off whatever it says in that middle band for Volts?

And engine running or not for that?

That 'third thing' is a shunt, used for the amperage measurement.

JustAnotherSaver

Out of interest would anyone care to hazard a guess as to when this is likely from?
I can't give anyone the answer tbh as my dad died a few years ago. The way he kept things i'd guess perhaps 80s or something but i could be out by a decade or more.

Nothing more than curiosity.

khcomp

Best guess is late 1970s

JustAnotherSaver

khcomp wrote: »

Best guess is late 1970s

Would certainly make sense. I know he was doing plenty of messing with cars back then and he was just handy in general at a whole range of different things, electronics included. Unfortunately i didn't inherit the ability.

khcomp

Then I won't mention the dwell angle setting...
Hang on to it, it's a nice relic!

Strider590

If that thing measures current without changing any leads around, then it has the potential to be quite dangerous, because if you connect it to a car and switch via the current/amp setting it'll short across the battery and go up in smoke with a surprising bang.

BeenThroughItAll

Strider590 wrote: »

If that thing measures current without changing any leads around, then it has the potential to be quite dangerous, because if you connect it to a car and switch via the current/amp setting it'll short across the battery and go up in smoke with a surprising bang.

That's why it has the shunt as the 'third thing' mentioned.

JustAnotherSaver

^^ The battery which i bought a couple years ago. Don't worry i have a trade card.

So i saw the garage tonight. He had some Snap On gizmo with a load of lights and numbers and switches on.
Basically he read it off with the engine off which (my memory can be terrible at times, was about 12v tops. He kept switching things on this thing.

He ran a test which basically said the battery was borderline in need of replacement. Another test said it was at 70% capacity.

Then we ran it with the engine on - volts were about the 11.8V marker. Turned electrics on bit by bit and he had me revving the car also, eventually all electrics on.

Now if i've remembered right then he said it should've been about 14V or so. I know a 14 was mentioned at some point but that the volts weren't getting any higher. They were between 11-12V and getting lower.

So he was leaning towards the alternator being the problem. The battery has that glass sight thing on it which from the looks of it says discharged and to fully charge.

So he says i'm to put it on a good full 24hours charge this time, battery off the car and then go back and test again but he's reckoning on it being the alternator and not the battery.