Rear Battery Arc

[Marmaduke’s Van]

Good afternoon all.

I’ve just changed both leisure batteries in my T5 Ocean and got a good arc/spark when I reconnected the rear battery.

Oddly the wire that sparked wasn’t one of the terminals but what could be an extra wire from the negative connector to the battery clamp bolt. There was no spark when I connected the negative terminal bock to the battery, only when I connected the additional wire.

I’m thinking that the main negative wire isn’t connected properly to the vehicle body if the extra wire sparks and also that there is a significant load/leakage even when everything is off.

Any one able to offer any wisdom?

Many thanks

 

[WelshGas]

Good afternoon all.

I’ve just changed both leisure batteries in my T5 Ocean and got a good arc/spark when I reconnected the rear battery.

Oddly the wire that sparked wasn’t one of the terminals but what could be an extra wire from the negative connector to the battery clamp bolt. There was no spark when I connected the negative terminal bock to the battery, only when I connected the additional wire.

I’m thinking that the main negative wire isn’t connected properly to the vehicle body if the extra wire sparks and also that there is a significant load/leakage even when everything is off.

Any one able to offer any wisdom?

Many thanks

How old is your vehicle? The Ocean model is the T6 onwards, prior to that it was the SE.

Are you the 1st owner?

See below the VW Leisure circuit wiring diagram.

The front Leisure battery is wired + and - to the rear battery that has the -tve terminal wired to a chassis earthing point, NOT the battery clamp bolt.

Had you charged both replacement batteries before fitting or checked that they had very similar voltages before connecting?

 

[Marmaduke’s Van]

Thanks the reply.

Still getting used to the terminology, we’ve only just bought it.

Both batteries were only delivered today with very similar voltages, with the front negative not even connected.

I’m wondering if there is a chassis connection issue and someone has added the extra wire as a work around?

Photo below for info. You can just see the terminal clamp with the black wire coming off it as well as the extra brown wire

 

[WelshGas]

Thanks the reply.

Still getting used to the terminology, we’ve only just bought it.

Both batteries were only delivered today with very similar voltages, with the front negative not even connected.

I’m wondering if there is a chassis connection issue and someone has added the extra wire as a work around?

Photo below for info. You can just see the terminal clamp with the black wire coming off it as well as the extra brown wire View attachment 106100

That is completely non-standard. BUT it maybe that the previous owner has re-sited the original earth wire.

See the photo below, 1 black cable + 1 Brown cable connected to the -tve terminal, but in this case the Brown cable passes behind the Leisure battery.

 

[Resfeber]

Looking at other posts regarding the Earth shunt should the brown wire not be the one that goes behind the battery and through the side panel to below the fridge where the Earth shunt is located?

This would mean that the Earth shunt has been disconnected from the leisure battery circuit in the OP‘s vehicle, potentially leading to iffy control unit readings and intermittent heater and fridge operation if battery voltages are not being correctly read by the control unit.

Shunt fix

Hi all. I’ve followed the VIP directions to fix the shunt and got the fridge out, now ready to do the repair. Seems I need to fit a new earth strap from shunt to the unused large diameter thread beside the wheel arch. My local dealer don’t know about this. They can sell me a shunt, but not the...

vwcaliforniaclub.com

see post #20 & #21 images

 

[WelshGas]

Looking at other posts regarding the Earth shunt should the brown wire not be the one that goes behind the battery and through the side panel to below the fridge where the Earth shunt is located?

This would mean that the Earth shunt has been disconnected from the leisure battery circuit in the OP‘s vehicle, potentially leading to iffy control unit readings and intermittent heater and fridge operation if battery voltages are not being correctly read by the control unit.

Shunt fix

Hi all. I’ve followed the VIP directions to fix the shunt and got the fridge out, now ready to do the repair. Seems I need to fit a new earth strap from shunt to the unused large diameter thread beside the wheel arch. My local dealer don’t know about this. They can sell me a shunt, but not the...

vwcaliforniaclub.com

see post #20 & #21 images

Thanks the reply.

Still getting used to the terminology, we’ve only just bought it.

Both batteries were only delivered today with very similar voltages, with the front negative not even connected.

I’m wondering if there is a chassis connection issue and someone has added the extra wire as a work around?

Photo below for info. You can just see the terminal clamp with the black wire coming off it as well as the extra brown wire View attachment 106100

See Post 5.
You May be correct or the original owner just put in a new ground wire. I think you might be correct, but if he has moved the brown cable from the shunt you shouldn’t be getting any voltage/amp readings on the Control Panel.

Shunt fix

Hi all. I’ve followed the VIP directions to fix the shunt and got the fridge out, now ready to do the repair. Seems I need to fit a new earth strap from shunt to the unused large diameter thread beside the wheel arch. My local dealer don’t know about this. They can sell me a shunt, but not the...

vwcaliforniaclub.com

 

[Marmaduke’s Van]

See Post 5.
You May be correct or the original owner just put in a new ground wire. I think you might be correct, but if he has moved the brown cable from the shunt you shouldn’t be getting any voltage/amp readings on the Control Panel.

Shunt fix

Hi all. I’ve followed the VIP directions to fix the shunt and got the fridge out, now ready to do the repair. Seems I need to fit a new earth strap from shunt to the unused large diameter thread beside the wheel arch. My local dealer don’t know about this. They can sell me a shunt, but not the...

vwcaliforniaclub.com

You’ve both got me thinking now! The control panel is giving sensible readings, although slightly lower than using a meter on the batteries directly.

The heater and fridge both work fine now and the indicted voltages/ loads seem appropriate.

I’ll see if my middle of Lidil endoscope still works and have a look under the fridge at the shunt.

Very many thanks for your thoughts.

 

[Resfeber]

You’ve both got me thinking now! The control panel is giving sensible readings, although slightly lower than using a meter on the batteries directly.

The heater and fridge both work fine now and the indicted voltages/ loads seem appropriate.

I’ll see if my middle of Lidil endoscope still works and have a look under the fridge at the shunt.

Very many thanks for your thoughts.

Would be good if you can find out with your endoscope if the original brown cable from rear battery -ve terminal to earth shunt terminal is still present and connected, in addition to this apparent extra earth.

 

[Resfeber]

See Post 5.
You May be correct or the original owner just put in a new ground wire. I think you might be correct, but if he has moved the brown cable from the shunt you shouldn’t be getting any voltage/amp readings on the Control Panel.

Shunt fix

Hi all. I’ve followed the VIP directions to fix the shunt and got the fridge out, now ready to do the repair. Seems I need to fit a new earth strap from shunt to the unused large diameter thread beside the wheel arch. My local dealer don’t know about this. They can sell me a shunt, but not the...

vwcaliforniaclub.com

Clear from this image that if there is no connection between shunt and rear battery -ve terminal then no readings of voltage or current would be possible on control unit.
However, if this was connected when the terminal was reconnected I cannot see how enough current would pass to earth when the additional lead in the OP photo was connected to the battery front clamp bolt as @Marmaduke’s Van observed?