Engine Battery Drain and Fuse #8 (Solved)

[R88]

I’ve experienced engine battery drainage issues since I got my converted van back from Rolling Homes, resulting in a dead battery on several occasions and not being able to start the van when needed.
It’s been to my VW dealer in Norwich twice. The first time they said that they’d charged the battery, there was no drain on it and there was nothing wrong, but it again fully drained within a week when sat idle. The second time they said that the battery was fine but that there was a 1.4amp drain, which they suspected was caused by the conversion (taking the easy way out!), so they now refuse to do anything unless the conversion wiring is removed.
The converters have come back to me with some feedback from their electrician, but overall it’s been of little help.
I carried out some experiments myself and got a 0.15-0.2amp drain, which drops to a normal level if I remove fuse 8, and that is apparently for the headlight switch. I tried disconnecting the headlight switch and plugging the fuse back in, but the drain is still there, so I’m wondering what else is fed through fuse 8?
With regard to the engine battery itself, I twice charged it in about 3.5hours from ~50% with a max 4amp charger, which I calculate to be a max input of 14ah. This does not seem very high for a battery that is supposed to have a capacity of 70ah and that VW say is absolutely fine.
Can anyone help with information about what is fed through fuse 8? If I can eliminate the drain problem, I can then go back to arguing with VW about the state of the battery.

 

[mmi]

what is fed through fuse 8?

5 Amp fuse in center dash? - just light switch.
Did you keep all the doors+hood closed and locked. Without doing so the BCM remains quite busy some time - the 0.2 Amps seems to be what I remember it drawing.

 

[Loz]

What make is the battery?

 

[R88]

mmi: Yes, the lower of the two orange 5A fuses in the left column of the centre dash fuse panel. When testing, I had the passenger door and bonnet open, but internal light switched off and I left it until the dash went blank and the amp reading settled down. It was around 0.15-0.2A with the fuse in and dropped to 0.06A with the fuse taken out, and the readings were the same with or without the headlight switch connected. The battery was constantly draining within a week with the fuse in, but with it taken out I've had no flat battery issues and the van is usable, albeit with the lights on all the time when the ignition is switched on, which I assume is a fail-safe feature.

 

[R88]

Loz: The battery is a Varta EFB+

 

[Nevtiger]

Hi,

Did you ever get to the bottom of this?

My new camper is doing the same :-(

 

[Niknak]

Check your split charge system if you can isolate I put an isolator in so can cut out all the camper system off if I want to, if you have a low lesiure battery and an issue with your split charge there a chance the batteries are equalising charge,

 

[Niknak]

Seen some right nightmare conversions with vehicle wiring all connected into, I like to keep it all separate as possible, better to have a flat lesiure battery than a vehicle battery

 

[Nevtiger]

The Van is a new Danbury conversion (Although actually converted Nov 2019 and in stock since then) so i hope its not doing anything silly.

I have been using the Leisure battery to start the van via jump leads....... as the main vehicle battery won't last a day without giving up.

I tried chasing a 'drain' but the van takes a long time to go to full sleep and stop a small drain on the battery. There seems to be no 'leak' in current due to the camper conversion., i checked the main battery current draw with the fridge on and off etc and the current draw was constant.

 

[Niknak]

Have you got the fridge on vehicle battery ?, could just be a duff battery

 

[Nevtiger]

Fridge is on the Leisure Battery.

My guess is that it is probably just knackered after been sat around for best part of 10 months before being sold. I think i will call VW Assist next time it happens and let VW sort it.

 

[R88]

No Nevtiger, I haven't got to the bottom of my issue yet. Without wiring diagrams or more vehicle knowledge, I'm not sure what else I can try. I have disconnected and isolated my domestic system from the vehicle electrics following instructions from the converters, but the starter battery drain is still there, so I'm pretty sure it's not due to the conversion. I had wondered if it could be my towbar wiring, but taking out fuse 8 for the headlight switch stops my battery drain and I don't think the towbar wiring connects directly to the light switch. Disconnecting the light switch does not stop the drain, so the switch isn't the problem, but 'mmi' said fuse 8 does not feed anything else, so I don't know what else to look for.

 

[nickg77]

I have exactly the same issue guys on mine - Varta battery. 2amp drain. Nothing obvious at all. I've isolated the camper side of things and still have the drain.

Tried a new battery, drained it in 3 days.

 

[Martinf]

And my drain is usually about .15A. But not always. I’ve never been able to work out what is taking the current.

 

[Shaun Witts]

...I don't think the towbar wiring connects directly to the light switch.

When I fitted the towbar wiring to my T6, there was a wiring option that was determined by what type of light wiring the van had On the back of the switch. One option involved some connection to the vans light wiring under the passenger seat, the other just joining 2 wires of the harness together.
So that does kind of infer there is a connection of some sort.

 

[Big.mac]

No Nevtiger, I haven't got to the bottom of my issue yet. Without wiring diagrams or more vehicle knowledge, I'm not sure what else I can try. I have disconnected and isolated my domestic system from the vehicle electrics following instructions from the converters, but the starter battery drain is still there, so I'm pretty sure it's not due to the conversion. I had wondered if it could be my towbar wiring, but taking out fuse 8 for the headlight switch stops my battery drain and I don't think the towbar wiring connects directly to the light switch. Disconnecting the light switch does not stop the drain, so the switch isn't the problem, but 'mmi' said fuse 8 does not feed anything else, so I don't know what else to look for.

Have you tried removing the fuse and then testing thoroughly to see if anything else stops working? In your original message you implied this started when it came back from the converters so it seems likely to me it is something they have done. Did they fit the tow bar at the same time?

 

[R88]

When I fitted the towbar wiring to my T6, there was a wiring option that was determined by what type of light wiring the van had On the back of the switch. One option involved some connection to the vans light wiring under the passenger seat, the other just joining 2 wires of the harness together.
So that does kind of infer there is a connection of some sort.

Yeah, that sounds like the towbar wiring fitting instructions I've seen. It tells you to pull out the light switch and look at the back of it, and then depending on which of two connector types it has, that determines how you connect up the wiring for the rear fog light under the passenger seat. However, even if this fog light wiring did come from the light switch, I'm not really sure how it could cause a drain through the light switch and fuse 8 if the fog lights are not actually switched on.

All I do know is that ever since I pulled out fuse 8, my van has been behaving itself and not ending up with a flat battery all the time. The only difference it makes is that my lights are on all the time with the ignition on, which I assume is a sort of fail safe in case of fuse 8 blowing.

 

[R88]

Have you tried removing the fuse and then testing thoroughly to see if anything else stops working? In your original message you implied this started when it came back from the converters so it seems likely to me it is something they have done. Did they fit the tow bar at the same time?

Yes I had come to the conclusion that it must have been something to do with what was done at the converters, and yes they did get the towbar fitted by someone while they had the van. Like I mentioned above, the only difference removing fuse 8 makes is that my light switch no longer works and the lights are on all the time with the ignition. However, it does remove the drain and stops the battery from flattening all the time.

 

[Big.mac]

Yes I had come to the conclusion that it must have been something to do with what was done at the converters, and yes they did get the towbar fitted by someone while they had the van. Like I mentioned above, the only difference removing fuse 8 makes is that my light switch no longer works and the lights are on all the time with the ignition. However, it does remove the drain and stops the battery from flattening all the time.

I assume that means you can’t switch your fog lights on either as they operate through the light switch? I guess you could disconnect the tow bar wiring in the connector under the seat and if that solves the problem it gives you the ability to take it back to the converters with a strong indicator that the problem is being caused by the tow bar wiring.

 

[R88]

I assume that means you can’t switch your fog lights on either as they operate through the light switch? I guess you could disconnect the tow bar wiring in the connector under the seat and if that solves the problem it gives you the ability to take it back to the converters with a strong indicator that the problem is being caused by the tow bar wiring.

Yes you are correct, I cannot turn on the fog lights with the fuse removed. However, I figured if I needed to use the light switch I'd just pop the fuse back in, as it only needs to be out to prevent the battery from draining, which is obviously not an issue while the engine is running.

Thank you for the advice, but as it happens I'm taking the van back to the converters soon anyway for them to sort out some other issues, and they are going to get their electrician in to look at it while they've got it. I might go and take a look under the seat anyway though, as I've not actually investigated the wiring under there before.