Leisure battery diode issue?

Sledgeracer · Sep 29, 2016

Hi all, would like your thoughts on this please. Over the summer while away in our Cali SE we twice ended up with flat starter battery and the nice AA coming out to start us.
First time we were at a festival and thought had just had the interior lights on too long with the doors open it me being stupid. Second time we were on hook up , had made sure the interior lights were switched off on the panel above the mirror , and no radio on etc. Starter batter flat after 1 1/2 days.
The only thing that we had changed from being away any other time we had the van was we were running a 12v cold box both times the starter went flat. We were running this from the 12v socket next to the sink.
Have had the van to VW up here and they say nothing wrong , no faults and that the 12v cool box will just pull a load of current and that then it flattens the starter battery.
That just seems like a fob off to me?
On both occasions , the leisure batteries remained pretty full and the fridge, lights etc worked fine , just all the stuff connected to the starter battery went.
I was reading on here about a diode being possibly the wrong way round? Where is this and how do I know which way round ?
Thanks for any help, not good being stuck with 2 little ones when trying to get home!

sidepod · Sep 29, 2016

how old is the van ?

First thought. Knackered starter battery?
Everything south of the drivers seat runs off leisure batteries.

andyinluton · Sep 29, 2016

I thought someone had established that on some vans that socket was run off the starter battery & one on the dashboard was run from the leisure batteries.

snowy55 · Sep 29, 2016

On some Calis the sink side 12v socket is run from the starter battery. There is a thread on here somewhere.

Hotel California · Sep 29, 2016

Think the diode info is in the download section.
If you become full member and pay the membership you get acces to many downloads and discounts.
If you plugged things in the 12v next to the sink it normally is powerd by the lesure bat.
Welcome on your first post btw.

WelshGas · Sep 29, 2016

snowy55 said:
On some Calis the sink side 12v socket is run from the starter battery. There is a thread on here somewhere.

And despite what VW might say, that should be a fault.
The only way to test would be with a Voltmeter and check all the socket voltages with the Engine battery disconnected.

However, I just don't see how it could happen with modern production methods as they use pre-made wiring looms and all the fuses for the habitation area are under the front seat in the SE.

Sledgeracer · Sep 29, 2016

Thanks for the replies everyone, very helpful. Will have a chat with VW and ask if they can check if that socket is connected to the starter battery.
Take the point on the diode that is unlikely to be that .
Once again thanks

bvddobb · Sep 29, 2016

We had the diode issue on our Cal, which is from Jan 2008. I believe it was rectified somewhere in 2010. From when is your Cali? If from between 2007-2010, you may have the issue and we can give you more details on it and how to rectify it.

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Sledgeracer · Sep 29, 2016

Hi, our Cali is a 2015. Thanks for the info , have just read the post on the digital voltmeter and testing where all the 12v sockets are powered from. I had assumed that the cupboard socket was from the leisure batteries as per the manual but it would appear not always. I bet it is that ours is off the starter as that is the socket the cool box was plugged into . Hadn't even considered that being the case ! Will check when she comes back from VW . Thanks again

sidepod · Sep 29, 2016

The tech manual in the download section (2004 Cali) shows the radio connected to the socket in question and the leisure batteries. Odd.

sidepod · Sep 29, 2016

I wonder if the split charge relay (J713) could be at fault.
If so the starter battery may be draining into the leisure batteries whilst parked.

Gavinskii · Sep 30, 2016

bvddobb said:
We had the diode issue on our Cal, which is from Jan 2008. I believe it was rectified somewhere in 2010. From when is your Cali? If from between 2007-2010, you may have the issue and we can give you more details on it and how to rectify it.

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I am interested to know more about this. I had a look in the technical section in members area, but can't find any info. Any help you can offer is greatly appreciated.

SimonB · Sep 30, 2016

andyinluton said:
I thought someone had established that on some vans that socket was run off the starter battery & one on the dashboard was run from the leisure batteries.

This is one of the threads on where the power comes from for each of the sockets
https://vwcaliforniaclub.com/threads/help-on-power.15078/#post-162272 We were told by our dealer that everything behind the front seats comes from the Leisure batteries and everything in front is from the starter battery. I have checked at least 4 Californias now and they were not wired up like this.
Ours is a 2015 model and at least 1 of the ones we checked was.
The socket on top of the dash is from the Leisure battery.
The one in the cup holder is from the starter battery.
The one on the side of the sink behind the passenger seat, in a UK model, is from the starter batter.
The other two, one under the bench seat by the sliding door and the one right in the back are from the Leisure battery.

andyinluton · Sep 30, 2016

Ours is also a 2015 model & Im 100% certain that the dash top socket is off the starter battery - it goes dead when the ignition is turned off. & the cupboard socket is fed from the leisure battery so completely the reverse of SimonB

Bigted · Sep 30, 2016

My 2015 beach - all sockets are off the leisure battery except the lower dash one (ashtray) which is starter. All stay live ignition on or off.

WelshGas · Sep 30, 2016

Bigted said:
My 2015 beach - all sockets are off the leisure battery except the lower dash one (ashtray) which is starter. All stay live ignition on or off.

Same on my SE.

bvddobb · Sep 30, 2016

It seems a bit like the fuse lay-out: like every build series has its own layout, and documented nowhere... You just have to find it out by yourself.

Gavinskii said:
I am interested to know more about this. I had a look in the technical section in members area, but can't find any info. Any help you can offer is greatly appreciated.

The diode issue is well documented on the german Caliboard, e.g. under this link. It is in german, but Google Translate is your friend!

In short:

Before 2007, the leisure and starter circuits were separate.

From 2007 onwards, they were coupled, in such a way that when one is on hookup and the leisure batteries are topped up, the charger will start to charge the starter battery. VW put a diode between the two circuits to make sure that current could run from leisure circuit to starter circuit (to charge), but not the other way around, so that the starter battery could never empty itself on leisure items.

BUT: in a series built roughly from 2007 into early 2008 THEY PUT IN THE DIODE THE WRONG WAY!! With the effect that:

The starter battery was never charged when on hookup (no current possible in that direction);
When the voltage of the leisure batteries dropped below that of the starter battery, the starter battery started to happily 'help' the leisure circuit, emptying itself on leisure items.

We had that happen on our first trip, when we used the parking heater a lot, the fridge, lights on, etc... And after a few days we need starter help

The german document states exactly by VIN which cars were effected.

The remedy is to solder the diode around yourself. Because, if you order a new one, using the part number on the diode, you will get a new one SOLDERED AROUND THE WRONG WAY AGAIN!

The diode is beneath the right cupboard, under the round lid you will find at the bottom of the cupboard. Open that, and you will easily recognise the diode. It has connectors on both sides, so you can easily remove it, solder it around and put it back.

We never had an empty starter battery again!! :bananadance

Sledgeracer · Oct 2, 2016

Thanks again guys , so frustrated with this , van was in at VW , no fault , lots of excuses like when the cool box is connected will draw lots of current and if the leisure batteries are running flat then it will start to use the starter battery !
Any way asked them to check where the sockets were connected to, any way rush to get the van and lady dealing with wasn't there etc. Get van home, thought I would check myself , unplug starter battery and lo and behold the socket in the cabinet is connected incorrectly to the starter battery . FYI in ours so is the one in the cup holder , the rest including dash top are off the leisure batteries.
( on a second note they also told me my camping heater was fine taken it apart no fault , get home, turn that on and thunk thunk thunk . Time to try a new van centre I think. What a waste of time)
Thanks for the posts guys , shouldn't have to diagnose these things ourselves though!

Joss Apps · Jan 8, 2021

So my 08 Cali appears to suffer from this and for years I've struggled with flat started battery.
Can't work out the campaign entry but the Chassis number is close! WV2ZZZ7HZ8H089267
I'll take a look for the diode tomorrow and get my multimeter ready