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Battery drained after long ride

Posted: 30 Jul 2025, 17:56
by FarWare12
I've been experiencing some electrical issues. I drove about 5 hours with the van and the next morning, the van would not start. The voltage on the battery was 9,4V, so I recharged it and this time the van started and drove without any issues.

During the 5 hour drive I experienced some electrical issues. The radio kept resetting. What I noticed previously, is that the radio would sometimes reset when switching the lights on. Also, the windshield wipers were returning very slowly to their starter position when turning them off. The drive must have taken a lot out of the battery because I had the lights on, the radio on some of the time and the heater on. Two weeks ago the blinkers were also not working, but I replaced fuse 21 and they have been working ever since.

I don't know if I have alternator issues or there is something wrong with my electrical setup. I drove quite a bit with the van in the past weeks and stayed mostly in campsites. I have two leisure batteries which I charge with a battery charger at campsites. The leisure batteries are also wired to a Cyrix CT which is wired to the starter battery. However, I've noticed the Cyrix never seems to charge the leisure batteries during the drive. I am not sure however if charging the other way is possible, in other words if the starter battery is also being charged when the leisure batteries are charged at the campsite. I also wonder if it's the Cyrix that's emptying my starter battery somehow.

After recharging my starter battery, I noticed the voltage is around 13,1V. After starting the van, the voltage is 12,86/12,9V. I believe this is too low?

How do I test what the problem is here?

Re: Battery drained after long ride

Posted: 30 Jul 2025, 20:01
by colinthefox
What engine?

Re: Battery drained after long ride

Posted: 31 Jul 2025, 05:36
by FarWare12
colinthefox wrote: 30 Jul 2025, 20:01 What engine?

WBX 1.9 petrol

Re: Battery drained after long ride

Posted: 31 Jul 2025, 07:54
by Aidan
alternator voltage regulator has probably failed/brushes worn out, so the engine and everything else has been draining the battery, easy to check with multimeter, if you don't see 14v ish at the battery with engine running then you are not charging the battery from the alternator
worth carying a spare with these old vans unless you know it has been replaced fairly recently, febi ones aren't expensive and are decent quality

Re: Battery drained after long ride

Posted: 31 Jul 2025, 08:02
by Oldiebut goodie
If your starter has been down to 9.4v you have almost certainly fooked it!

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Re: Battery drained after long ride

Posted: 31 Jul 2025, 08:59
by colinthefox
FarWare12 wrote: 31 Jul 2025, 05:36
colinthefox wrote: 30 Jul 2025, 20:01 What engine?

WBX 1.9 petrol

The reason I asked was because I had a similar problem due to glow plug relay malfunction. That won't apply to a 1.9wbx!
Best to include engine type in your signature to avoid confusion.

Re: Battery drained after long ride

Posted: 31 Jul 2025, 10:50
by ZsZ
It seems like your alternator is not charging. With a fully charged battery running on idle measuring at the battery voltage should be around 13.8V on a petrol van.

Check voltage at the alternator stud, at the starter stud, and at the battery. Check the ground strap at the nose of the tranny. Clean all the contacts, ground paths.
The alternator might charge OK, but the voltage cannot reach the battery.

Check the blue wire of the alternator.
The aternator might not excite - although then the dash light should illuminate.

Re: Battery drained after long ride

Posted: 01 Aug 2025, 09:42
by FarWare12
Aidan wrote: 31 Jul 2025, 07:54 alternator voltage regulator has probably failed/brushes worn out, so the engine and everything else has been draining the battery, easy to check with multimeter, if you don't see 14v ish at the battery with engine running then you are not charging the battery from the alternator
worth carying a spare with these old vans unless you know it has been replaced fairly recently, febi ones aren't expensive and are decent quality

Right now I'm seeing 12,9V with the battery off, 13,1V with the engine running. But this goes down to 12,7/12,8V if I put radio/lights/heater on. So it seems the alternator is charging somewhat but not fully.

I haven't checked the alternator itself yet. Will do so this weekend.

Re: Battery drained after long ride

Posted: 02 Aug 2025, 18:19
by Mocki
Petrol WBX have a known weak link in the charge circuit as they age , the main wire from the alternator to the starter motor ( and thus to the battery ) rots internally , goes high resistance and eventually breaks down completely , meaning you have charge coming out of the alternator but not much ( if any) gets to the battery .
Take a voltage reading at the alternator ( using the casing as neg )
If you have less than 14v between the alternator output and the casing , either the blue wire isnt connecting or the brush pack is faulty
If you have 14v on the first test Then take another another from the alternator pos using the van body as neg connection , if there is any difference between these two readings clean the earths , both the actual facings on the alternator to the bracket and the gear box nose earth strap , then take another voltage reading at the battery .
If you have a difference of more than 0.5v between those readings and the readings at the battery it’s connections or wire fault,
Clean earth faces and earth leads .

Re: Battery drained after long ride

Posted: 03 Aug 2025, 06:42
by TwinTurbo
big tip. don't use a multimeter to check for voltage. use a 25w bulb.  A multi meter draws very little current and can easily show a voltage on a circuit and look good, but once uou put a real load on the circuit it can expose faulty cable or connections.