Starter to Battery Rewire - Already done?

[bmouthboyo]

So as with most things on my early T25 it has undergone many modifications by past owners (Engine, Gearbox etc) and so most of the time I am trying to find out whats standard and whats not.

I went to rewire the Starter to Battery cable this month and had all the wire purchased, crimp tools, terminals etc however when I finally got round to it I noticed the cable already installed seems even bigger than that which I purchased (24mm2).

I only had 2 weeks to work on the van this year as I live abroad and so moved onto a few other jobs, but thought I would check here if it might still be worth doing in the future.

I measured the diameter of the Main starter cable and the dash fuse box wire and these are the measurements (I know wire insulation may throw these):


10.4mm Outer Diameter


5mm Outer Diameter

Providing the terminals are in good nick should I just leave the starter cable as is and add a new live feed for a separate fuse box under the dash for the heavier load items as this seems to be the original 6mm2 one at the moment?

Lastly I measured the voltage across the terminals with the engine running (no idea if this is the correct method) and I got 13.57v:



Does this look about right?

Cheers

[bigherb]

I went to rewire the Starter to Battery cable this month and had all the wire purchased, crimp tools, terminals etc however when I finally got round to it I noticed the cable already installed seems even bigger than that which I purchased (24mm2).

Cheers

That looks like the original cable which was 35mm2 for early vans and then 70mm2 for later vans.
If the cable is OK at both ends there is no need to replace it.
The charging voltage looks a bit low it should be minimum of 13.8V

[bmouthboyo]

I went to rewire the Starter to Battery cable this month and had all the wire purchased, crimp tools, terminals etc however when I finally got round to it I noticed the cable already installed seems even bigger than that which I purchased (24mm2).

Cheers

That looks like the original cable which was 35mm2 for early vans and then 70mm2 for later vans.
If the cable is OK at both ends there is no need to replace it.
The charging voltage looks a bit low it should be minimum of 13.8V

Any ideas what could cause the lower voltage? Alternator or something else?

The battery is pretty old and not used in over a year apart from an overnight charge, would that effect it?

[bmouthboyo]

I went to rewire the Starter to Battery cable this month and had all the wire purchased, crimp tools, terminals etc however when I finally got round to it I noticed the cable already installed seems even bigger than that which I purchased (24mm2).

Cheers

That looks like the original cable which was 35mm2 for early vans and then 70mm2 for later vans.
If the cable is OK at both ends there is no need to replace it.
The charging voltage looks a bit low it should be minimum of 13.8V

Any ideas what could cause the lower voltage? Alternator or something else?

The battery is pretty old and not used in over a year apart from an overnight charge, would that effect it?

[ghost123uk]

If the battery starts the van ok, then it is ok and won't be the cause of low charging voltage.

The first thing to do is measure the voltage at the fat output wire on the back of the alternator, using the alternator body as "earth" for your black meter probe. If it is less than 13.8 Volts there too, then the cause is almost certainly the little box that is held onto the back of the alternator with 2 screws, about 2" apart. It is a voltage regulator and brush pack.

They do wear out and are only £10 to £15 to buy and only take minutes to replace. Suggest getting a replacement from Brickwerks as you will then be sure of getting the correct thing and of good quality. After fitting you should see about 14V at the battery.

[CovKid]

Theres also a 14.5v version around but to be honest this is kind of sticking a plaster on things.

and in case you missed it:
https://club8090.co.uk/wiki/VW ... ain_cables" onclick="window.open(this.href);return false;

and
https://club8090.co.uk/wiki/VW ... ry_to_dash" onclick="window.open(this.href);return false;

[bmouthboyo]

Theres also a 14.5v version around but to be honest this is kind of sticking a plaster on things.

and in case you missed it:
https://club8090.co.uk/wiki/VW ... ain_cables" onclick="window.open(this.href);return false;

and
https://club8090.co.uk/wiki/VW ... ry_to_dash" onclick="window.open(this.href);return false;

Sorry what do you mean by 'sticking a plaster on things'? Do you mean it could be something else? Alternator itself on the way out?

I am not sure if it makes any difference but my engine and alternator are from a Mk1 Gti:

[bigherb]

Do what ghost said first, you need a starting point of the alternator output voltage before you do anything else.

[CovKid]

Agree, and don't forget voltage drop.

[ghost123uk]

I measured the voltage across the terminals with the engine running (no idea if this is the correct method) and I got 13.57v Does this look about right?

and don't forget voltage drop.

I know, it's too hot today to be explaining what that means in this situation to someone not fully conversant in such matters

p.s. bmouthboyo at this stage it's nothing to worry about.
Basically, if the voltage measured at the alternators output is more than about .2 of a Volt higher than when measured at the battery, with the engine running and the headlights on, then you are getting a voltage drop in either the main cable from the alternator to the battery, or in one of 2 earthing cables.
As BigHerb intimated, do one thing at a time. First measure the output of the alternator