Alternator and Starter rewire.

[shepster]

I'm about to rewire the Alternator and starter circuit following the Wiki info and would just like to confirm something.

The 2 cables going from the Alternator to the black box can be done away with and replaced with a larger one that goes directly between Alternator and starter then from starter directly to the positive side of the battery.

So far so good, my question is what is the other thick cable in the black box and do I still need a connection from the Alternator to the 'post'?

I'll be using 25mm cable for both runs as it's what I happen to have lying around.

Reason for doing this is after changing the brush pack I'm still only getting 13.6v at the battery yet 14.4 at the Alternator.

Thanks in advance.

[Mocki]

You still need power to that post for the manifold heater .
Are you sure it’s not the -12v ( chassis neg) that is loosing your volts ? Alternator contact to engine, engine to body ??

[shepster]

You still need power to that post for the manifold heater .
Are you sure it’s not the -12v ( chassis neg) that is loosing your volts ? Alternator contact to engine, engine to body ??

I've a second earth from starter to chassis and the gearbox earth was changed last year so pretty happy with those, the starter spins up nicely so I'm guessing the earth is sound?

I haven't got an extra earth from alternator as I assumed the bracketry would be adequate and when I tested the voltage I used the body as the earth point and saw 14.4 so presumed its good.

So just to confirm the 2 cables that are crimped together that go to the Alternator can be done away with but I need to replace them in order to power the manifold heater or have I misunderstood?

[davidoft1]

Try putting your multi meter into the cable at the battery rather than on the battery terminal , is your van diesel or petrol ?

[Robsey]

Try putting your multi meter into the cable at the battery rather than on the battery terminal , is your van diesel or petrol ?

Signature says 2.1 petrol, but running a carb.

[shepster]

2.1 so battery under drivers seat, I can try at the cable rather than on the terminal but why would that make a difference?

[davidoft1]

2.1 so battery under drivers seat, I can try at the cable rather than on the terminal but why would that make a difference?

Poor conduction through the terminal or the terminal’s connection to the battery post but that level of volt drop over 10-12 ft of cable isn’t unusual, what happens to the voltage if you check when not running and after running for 5 mins ? , what happens if you disconnect the battery and check the voltage at the battery whilst running ?