alternator for only outputting 12.8v

[milfredo]

I noticed that my stereo that is powered off the leisure battery wasn’t charging as I can see the voltage reading on the radio. I thought this might be a problem with the split charge relay, but after checking the output of my alternator, it’s only putting out 12.8 V when I put the multimeter from the output of the alternator and the other ground. This is the same voltage that I measure across the battery. Terminals is my alternator knackered as I thought they should be at least 14 V when running (tick over)?

 

[milfredo]

I noticed that my stereo that is powered off the leisure battery wasn’t charging as I can see the voltage reading on the radio. I thought this might be a problem with the split charge relay, but after checking the output of my alternator, it’s only putting out 12.8 V when I put the multimeter from the output of the alternator and the other ground. This is the same voltage that I measure across the battery. Terminals is my alternator knackered as I thought they should be at least 14 V when running (tick over)?

When I rev the engine to about 2000rpm, it goes to 12.9 ish.

 

[sparkywig]

It's not charging, have you got an internal or external regulator?

 

[milfredo]

It's not charging, have you got an internal or external regulator?

Altinator. I drove it all day yesterday and the main battery is still showing 12.8v across the terminals without the engine on.

 

[milfredo]

Altinator. I drove it all day yesterday and the main battery is still showing 12.8v across the terminals without the engine on.

I might add, the clock runs 24/7 and the engine still turns and starts on a dime.

 

[milfredo]

Altinator. I drove it all day yesterday and the main battery is still showing 12.8v across the terminals without the engine on.

Sorry, I don’t know if it’s internal or external. I guess it’s internal as I’ve not seen a regulator while going over the bus.

Also worth noting that the charging light goes out once the engine is running.

 

[sparkywig]

The battery is good, 12.8V is spot on for a fully charged battery.
Have you tried measuring alternator output with everything electrical turned on?

 

[milfredo]

The battery is good, 12.8V is spot on for a fully charged battery.
Have you tried measuring alternator output with everything electrical turned on?

No I’ve not. I jumped ahead and pulled out the contacts. One is a lot shorter which is odd.

This is a hella. Does anyone know of spares?

 

[milfredo]

The battery is good, 12.8V is spot on for a fully charged battery.
Have you tried measuring alternator output with everything electrical turned on?

With everything on; lights, wipers on full and hazards, I get 13.8 v output from the alt’. Seems ok considering the above photo.

 

[milfredo]

With everything on; lights, wipers on full and hazards, I get 13.8 v output from the alt’. Seems ok considering the above photo.

And now my stereo is showing charging via the split relay.

This is what set me off in the first place.

I ran a pencil rubber around the inside of the alternator and some wire wool on the graphite prongs. Looks as though I need a new bit (please not a new alternator!)

 

[milfredo]

Can not find a spare. There is no part number on the bit I removed.

 

[sparkywig]

That's OK, charging output should be between 13.5V and 14.5V depending on load.

 

[purpledog07]

Yes on the stereo looks ok now. 13.6V at tickover ain't bad.
If you really want new carbon brushes just take them to a local alternator refurb or auto electrician. They will be able to source. They shouldn't be expensive really either.
Otherwise, get the numbers off the alternator, they may be very common as VW didn't use that many. Bosch or hella generally. There may be only one hella alternator used for your engine?
Measure them and search for vw hella alternator brushes. Worth a punt.
I needed brushes for an ancient vintage sewing machine and ended up buying similar and sanding down to fit in the original holders. Just be careful, they are brittle!

 

[milfredo]

Yes on the stereo looks ok now. 13.6V at tickover ain't bad.
If you really want new carbon brushes just take them to a local alternator refurb or auto electrician. They will be able to source. They shouldn't be expensive really either.
Otherwise, get the numbers off the alternator, they may be very common as VW didn't use that many. Bosch or hella generally. There may be only one hella alternator used for your engine?
Measure them and search for vw hella alternator brushes. Worth a punt.
I needed brushes for an ancient vintage sewing machine and ended up buying similar and sanding down to fit in the original holders. Just be careful, they are brittle!

There are no part numbers on the brush ‘module’ and I’m not keen on removing the whole alternator until I have to. Double annoying; the brushes are part of the whole module and non-removable. You need the complete unit.

 

[purpledog07]

Bugger

 

[milfredo]

If I had to buy a new one (the bus needs to be reliable for the six hour journey to Glastonbury), is it wise to get the 70amp version or will it likely be a lot larger?

 

[purpledog07]

Not sure, I would assume it is the same dims on the outside if listed for your engine as it would beed to fit the pedestal.
If you can afford it get a bosch unit, they make a 55amp and they have replaceable brushes usually. Pricey though.
Best option would be to get yours refurbished if possible, have a search for places that rebuild them.

 

[Mechanoid]

You might be able to just change the carbon brushes in the holder. You need to unsolder the wires going to the brushes. Measure the brush sizes and try and match them up. That's if you are keen not to have to buy a new alternator!

 

[milfredo]

You might be able to just change the carbon brushes in the holder. You need to unsolder the wires going to the brushes. Measure the brush sizes and try and match them up. That's if you are keen not to have to buy a new alternator!

I bought a new unit and swapped the brushes to see if made a difference and it didn't

Today I fitted the new alternator and the was not a fun job, made even harder but the engine bay being so low down. I couldn't get the fan undone from behind the shroud so a lot of bits needed to come off. New unit is chucking out 13.8v