Why doesn’t my battery charge?

payydg · Sep 25, 2021

After having the engine and transmission out it’s all back together. Starts fine. Problem is alternator doesn’t charge at the battery.

Theres charge coming out of the back of the alternator (about 15 volts) it’s just not getting to the battery. All the wires are connected.

I’m going to get the multimeter out tomorrow but how does the charging system work? There’s no wire directly from the alternator to the battery? The thick brown wire from to the battery goes to a relay in the engine bay (photo two) and the a couple of wires go from the alternator to a plug (photo 1).

Any thought. Have I ****ed something up?

kermit_rr · Sep 25, 2021

There should be a big thick cable (finger thickness) going direct to the battery from the alternator. There should be another thick cable going to the fusebox from the battery.
There should be an earth of the same thickness going from the chassis to the battery

kermit_rr · Sep 25, 2021

Non of the wires in your pics are thick enough for alternator output

payydg · Sep 25, 2021

kermit_rr said:
There should be a big thick cable (finger thickness) going direct to the battery from the alternator. There should be another thick cable going to the fusebox from the battery.
There should be an earth of the same thickness going from the chassis to the battery

Thanks mate. It seems the thick brown cable goes from the battery to the relay in picture two - you can just see the brown cable at the bottom of that picture.

maybe the cable you describe has got hidden behind something and I didn’t notice

lynall · Sep 25, 2021

Most cars have the alt wire running direct to the positive terminal on the starter motor, then a fatter cable from that terminal back to the battery positive.

Scooby22 · Sep 25, 2021

Not sure what model/engine you have but this is a 300 tdi diagram.

m

payydg · Sep 25, 2021

Scooby22 said:
Not sure what model/engine you have but this is a 300 tdi diagram.
View attachment 248849m

Thanks, it a 200 tdi but maybe I missed a wire that connects to the starter

payydg · Sep 26, 2021

You were all right I’d missed the cable from alternator to starter

Why doesn’t my battery charge?

payydg

Well-Known Member

kermit_rr

Very

kermit_rr

Very

payydg

Well-Known Member

lynall

Well-Known Member

Scooby22

Well-Known Member

payydg

Well-Known Member

payydg

Well-Known Member

Similar threads