Starter Battery Wiring - VW Disagreement

[Ann3x]

Interesting one. I've had a few problems with my starter battery discharging (its a Varta, not a Moll so thats not the issue!). Basically my battery goes flat after around 5-7d inactivity. Thats pretty short imo. This was an issue before lockdown and is not just due to the extended hiatus.

I've taken it into VW Liverpool for a look and they told me the battery charges fine and the problem is my leisure wiring. Specifically that it's discharging due to the wiring onto the negative battery terminal. Their position is that NOTHING should ever be attached to the starter negative due to the shunt and the drain is due to my wiring.

I have the following items wired to my starter negative:

• BM2 monitor
• VB Air Pump for Suspension (fitted by an approved VB installer so I would assume its done right)
• B2B Common negative (fed to cabin)

I don't see any issue with the above items - the B2B specifically says to use a common negative (not a chassis earth), BM2 has to be wired across terminals, VB I can only assume is wired right (Ill ask the installer tho).

Is the VW guy talking cr*p?

 

[Deaky]

Sounds about right to me. If your B2B -ve is connected to the battery post then the van won't be aware of the amps being taken out of the starter battery by the B2B charger and the alternator won't be replacing them. This will mean your starter battery is always in a lower SOC than is should be.

Their position is that NOTHING should ever be attached to the starter negative due to the shunt and the drain is due to my wiring.

Correct

 

[Ann3x]

Sounds about right to me. If your B2B -ve is connected to the battery post then the van won't be aware of the amps being taken out of the starter battery by the B2B charger and the alternator won't be replacing them. This will mean your starter battery is always in a lower SOC than is should be.


Correct

So your B2B negative goes to a chassis earth? My Sterling's manual explicitly says not to do this.

 

[Deaky]

So your B2B negative goes to a chassis earth? My Sterling's manual explicitly says not to do this.

Yes

 

[Ann3x]

Yes

Clear, Ill change my wiring to chassis earth. Learn something new every day.

 

[Deaky]

Clear, Ill change my wiring to chassis earth. Learn something new every day.

I'd move your VB air too. There is an earth point under the scuttle panel just behind the battery.

 

[Dellmassive]

That's correct.

All ground connections to body ground.

Only the vw shunt to the battery neg post.

Or the van wont see the drain from your loads and assume the battery is charged when it isn't.

 

[Ann3x]

I'd move your VB air too. There is an earth point under the scuttle panel just behind the battery.

Its only been in a week so ill be calling the installer about that!

 

[Ann3x]

Here's the Sterling manual, relevant bit in red, kinda surprised this is so wrong:

 

[Nigel W]

My Sterling negative is connected to the battery post as well (installed by converter) so following this with interest.
if it is decided best to remove any suggestions where to, near the battery please.
i have also just emailed my converter to ask why - will revert.

 

[Pauly]

Follow the main negative coming away from the shunt and you will see the main engine earth point down to the left of the battery (the cables only about 18 inches long)
Its a bit fiddly to get at with everything in situ

 

[Loz]

Here's the Sterling manual, relevant bit in red, kinda surprised this is so wrong:

Doesn't cater for smart alternator setup with battery shunt.

 

[Ann3x]

Doesn't cater for smart alternator setup with battery shunt.

Clearly. Just a bad oversight considering that its a B2B specifically stated to work with smart alternators.

I guess I can just terminate the current negative cable between starter and leisure and run my leisure battery negative to the earthing stud under the seat. VB ill have to check with the convertor on.

 

[Deaky]

Clearly. Just a bad oversight considering that its a B2B specifically stated to work with smart alternators.

I guess I can just terminate the current negative cable between starter and leisure and run my leisure battery negative to the earthing stud under the seat. VB ill have to check with the convertor on.

That's how my Redarc is connected.

 

[Ann3x]

VB guy has never heard of the need to avoid the negative terminal either but "no issues with using a chassis negative" so ill move that one too.

It amazes me what professional convertors dont know (but this forum does).

Thanks everyone.

 

[Nigel W]

As I already have the cable running to the battery and I don’t have a clue where, or the knowledge, how to shorten and then fix to a stud under the seat could I fix it to this point which dellmassive showed on another thread? If it’s long enough to reach.
or is there another point I can get to with my arthritic hands?

 

[Jollyvan]

So just to get this clear ALL negative connections to body earth and not battery terminal. My westfalia tow bar electrics all go to the battery as does my BM2 monitor. Just as an aside I have lots of wires terminating on the positive post has anyone got a tidy solution to this?

 

[Martinf]

VB guy has never heard of the need to avoid the negative terminal

I've just realised that it appears my VB negative also goes direct to the battery negative post. Maybe the cause of my battery charge challenges?

I guess I should discuss this with my VB installer. Anyone know their approved installation configuration?

In the photo the two small black cables are my battery monitors, but the bundled brown and yellow cables behind are I believe my VB negative.

 

[Nigel W]

Help.....I have moved the negative cable to the headlight bracket bolt as per pic a few comments up but after looking at one of the guides Loz has done there is a ground point underneath the front plastic scuttle - how does this scuttle come off I can see no fixing points?
is it worth the effort or do you think my bracket bolt is good enough? (the BtoB still lights up so there is a circuit)
thanks guys.

 

[Ann3x]

Help.....I have moved the negative cable to the headlight bracket bolt as per pic a few comments up but after looking at one of the guides Loz has done there is a ground point underneath the front plastic scuttle - how does this scuttle come off I can see no fixing points?
is it worth the effort or do you think my bracket bolt is good enough? (the BtoB still lights up so there is a circuit)
thanks guys.

Read this: T5 scuttlebay soundproofing