VW T5 camper battery issue / alternator issue (possibly) … help pls!

Hi, so after much searching, we’ve finally found and for a T5 camper conversion, T5 2011, 2L. V chuffed so far but v early days!

It wouldn’t start yesterday after a longish journey the day before. Pretty sure I didn’t leave anything on, and it runs 2 leisure batteries so they should’ve looked after bits and pieces if I did?

The battery has been tested at Halfords with a glowing report.
I did pick up a battery drain yesterday (multimeter in series on -ve terminal) but pulling each dash fuse individually didn’t change the reading.
Left the battery unattached overnight and voltage unchanged, and van started perfectly this morning.
Checked battery drain again and it seems to have gone???

Noticed that I’m getting 13.8V when engine running – is this too low to properly charge the battery? Wonder if a failing alternator is the problem? It does have a split charger.

Have tried a few autoelectricians but the earliest I can get one is September!! We’re due off for a trip on Thursday, so a bit stressed!

Any advice would be fab. Thanks

Has it got a solar set up and /or relay? Leisure battery is factory fitted for the heater.

The guy that fitted our solar* cocked up /was inept and our motor battery kept draining. He couldn’t work out how to connect the solar without disrupting the leisure battery relay. Ended up leaving the van with my mechanic for a couple of weeks to find the fault (each fuse out, wait 20 mins before taking a reading, blah blah blah).

*Visiontech near Colchester

Edit… By relay I mean split charger

You’ll likely have 2 pieces of equipment in there: a ‘split charger’ of some kind, and a distribution unit of some kind. Check the distribution unit isn’t set to allow drain from leisure to main battery. That might account for a voltage drain seen on the main -ve terminal.

13.8v is the charging voltage IIRC.

I’d be disconnecting the split charge first and seeing if the battery drain is still there, that’s most likely to be the weak point.

Yes to solar. It’s been converted a good few years and the couple who sold it seemed v v trustworthy, and they’re mystified to this new problem.

Distribution unit, new one for me but will hint for it…any further info as to how to check?

And 13.8v alternator charging, that ok?

Thanks

Leisure vehicle distribution units can take many forms, but its the bit of kit you use to enable the leisure power, or power to the fridge, etc, etc. Google “PMS 3V” and see if you have something similar.

Brilliant, off to look at lunch break

Might be worth checking that your van doesn’t have a Smart Alternator, if it does then I don’t think it can use a Split Charge Relay and would need a Battery to Battery Charger instead. My parents T5 had been fitted with the former and it eventually borked the battery.

If the alternator is putting out a constant 13.8v then it shouldn’t be a smart one. With the smart alternators they vary between 0 and 14.1v. That’s what plays havoc with split charge relays, since they are only really designed to work with a constant charge rate. I found mine could be ‘fooled’ by setting the fan to position 2 so that the alternator stays on constantly, but I do need to get round to fitting a DC DC charger soon!

I’ve just had this same problem on my Trafic camper conversion that I completed last year.
A couple of months ago the starter battery would randomly be flat (luckily I used a Victron relay so I could use the leisure battery to jump the van in an emergency), I checked everything and had a pal who’s an electrical engineer to check it out but to no avail. Conclusion was it was just a knackered starter battery, we’ve had the van 6 years (it’s a ’10 plate) and reckon it was still the original battery. New battery in and it’s been spot on since. I’d be getting a second opinion on the state of yours.

Actually that’s a good point – ‘tested’ can mean a whole host of things. If the battery is more than a couple of years old I’d think about a new one, if only to eliminate it.

Thanks all. Took it for several 20min drives yesterday, to work the battery a little. Left it connected up overnight and this morning, 12.85V, started spot-on.

Can’t detect a drain, so maybe I goofed on this with my multimeter. Owner is relieved (and seem v genuine), wonders if he left something on as he passed it over to me … but can’t think what.

We’re due off Thurs for a night or 2, so time will tell!

I have a mystery random drain on my T5. If you are stressing Just buy a lithium booster pack they are tiny and very useful if you get stuck some where

Old batteries can and do cause random issues. Maybe get a new one and have the old one as a spare in the van, just in case.

good thinking, off to check lithium booster packs!

Our T5.1 will discharge it’s starter battery after about 3 weeks of standing without use.
I’ve ended up getting a smart charger to keep it reasonably conditioned.

The favourite one for Battery drain in a T5 was always aftermarket head units. But overnight wouldn’t usually be long enough to do it and it shouldn’t have just appeared if nothing’s been changed.

If it plays up again first thing I’d probably do is disconnect the split charge by removing the fuse and seeing if it goes away (depending on set up you’ll likely find a Midi fuse near starter and leisure batteries).

Morning, flat battery this morning. Didn’t use the van yesterday as wanted to see ifthe battery drained. I’m suspecting the battery’s on its last legs as suggested above, off to Halfords as need one pronto!

I booked online with the AA to come and fit one for me – cost about £170 fitted for my 84bhp t5.1
Bewildering array he had with him – I would not have picked the correct one. Extremely happy with the service

Replaced battery at lunchtime and checked for battery drain and it’s around 240mA.

There are 2 leisure batteries with a split charger. One leisure battery powered primarily by solar (I think) and one primarily by the engine. Battery drain was a bit erratic yesterday and sounded like the drive battery was quite old, so I replaced it with a Bosch this morning. Drain continued. Pulled fuses one by one with no change. Pulled split charger fuse no change.

Disconnected leisure battery at solar end, and drain disappeared.

So I’m hopeful we can go off tomorrow for a couple of nights with one leisure battery disconnected – is this OK to do?

And any clues as to why that leisure battery/solar powering is causing a drain?

Appreciate it’s really tricky without seeing all the detail, but very new to multiple batteries and split chargers etc, so any broad pointers would be great.

Sounds like the solar diode pack has died causing the solar panels to discharge when not producing enough energy to balance and overcome the voltage of the battery.

Mine did this, there is a Bolt in 100Amp Fuse Hidden under the Battery Tray – AA Man did a lot of digging to find it, but that was the root cause on mine, a mechanic shorted something during a service. Alternator light would go out when Revved and drove to London from Yorkshire no problem, but despite the Alternator light not been illuminated battery was not charging.

There should be a diode preventing reverse discharge through the panel. Depending on who wired the solar setup in this might have been omitted or not working. When the potential difference between the panel reverses, IE during the hours of darkness the battery can in effect power the solar panel. Don’t know what this is called but my charge controller has one built in. Check it out :o)

You should be fine with one leisure battery for a shortish trip.

One leisure battery powered primarily by solar (I think) and one primarily by the engine.

This is an odd set up. Usually 2 batteries would be wired in parallel and treated as a single big battery.

Get some photos / diagram up after your trip 🙂

Thanks all, this is when I love STW!

Just checked the battery after leaving it all overnight (with one leisure battery (the solar one)) disconnected. Drive battery at 12.8V, van started on the button.

So we’re off shortly for (hopefully!) a couple of nights and when I’m back, I will get some pics up of the wiring/batteries – really appreciate the help and my description of the set-up might well be incorrect. Have phoned a couple of autoelectricians and they’re rammed, Sept was the earliest!