We are currently in the Alps in our motorhome, how we made it I don’t know. I’m not sure we’re going to make it back unless someone can help solve this total mystery.

Van is a coachbuilt on a Fiat 2.3 diesel, 2008 (Ci conversion)

Our charging system is failing but appears to be failing randomly. We drove from swindon to Dover fine and stopped the van waiting for the ferry. Then I started it to drive on and got the battery warning light. I thought this was odd but ignored it. Driving off the ferry warning light again. We stopped in a layby and I measured voltage over the battery, 12.4 volts. Not good as it should be 14v with the alternator going.

I stopped then started the van and the voltage went up to 14v. So we decided to keep going.

We then drove 200 miles and stopped for diesel. Starting the van, warning light comes on again. No amount of fiddling or fuse pulling can get it to go away. Our only choice was to gamble, so we drove another 120 miles until the battery was near flat (I have a spare) and camped for the night.

Next morning, the van just about manages to start on the old battery, and guess what 14v at the battery. We drive 300km and stop for diesel. Start again and the warning light is back on.

The only link I can make is a warm engine is causing it and there is some sort of relay/cut-out circuit that is killing the charging current to the battery. There must be a split charging circuit as the leisure battery charges when we are moving.

I have 4 days to fix this before we head home. I’m pretty certain the alternator is ok (when it works) as it is brand new (replaced in Feb).

What else should I check? I cannot find the schematics for the van online and don’t have them with us. Any other ideas most greatly appreciated. All comedy will be laughed at in that “wish you were here in this situation” type way 😉

Thanks in advance. This place is usually tops for sound advice mixed in with the noise.

ps. locals say DO NOT use a mechanic/electrician in this area if you ever want to start the van again.

ps. apols for bike forum posting..it’s the stress that did it

Well, I just read that and thought the alternator was goosed, until the part where you said you had a new alternator fitted. Could the new one be faulty?

could be sticking brushes in the alternator,or poss dry joint,or diode failing,or of course the obvious slipping belt ? you really need an amp meter to test charging,not a volt meter.

obviously something is draining power, when its dark look for any lights on,even dim, heated windows/mirrros,etc, can drain the power.

As project said, sounds like something is draining power, and pretty fast by the sounds of things…

However, have a look at the main battery earths – make sure they are tight/clean/etc.

Is the voltage at the leisure batteries staying at 14v even when the warning light is on and the starter battery is 12.4v? If so, give the earth strap between starter battery and chassis a firm tug. Also check the earth strap between engine and chassis.

If the alternator is driven by a V groove belt, check the grooves are not too worn as this can cause slippage. It would normally be replaced along with the new alternator though… Check the tensioner is tensioning if you can reach it. Check positive cable between alternator and battery.

My van had an issue where the voltage would start off at 14.4v and then gradually drop until after an hour or so of driving, the voltage would fall to around 13.5v and the split charge for my leisure batteries would disconnect. It was the alternator.

Finally, if you get some jump leads long enough, you may find you can connect the leisure and starter battery together so you can use the leisure batteries to provide power whilst driving. It would give you a bit more range. Normally they would be connected whilst driving but if the voltage drops they will disconnect as the split charge will think the engine has stopped.

Edit: I don’t think its something consuming power as there’s nothing on the van that will suck the alternator voltage down from 14.4 to 12.4v.

Work out how many batteries you’d need to use to get home and just buy that many and change as they go flat?

Poor earth or battery + connection
Drop of washing up liquid on alternator pully to degrease incase its slipping

Thanks for all of that. One further bit of evidence

There is a PCB behind the seat which controls the charging of the leisure battery. I notice that when starting the fridge DC light goes on for 10 seconds then I hear a “click” then it goes off. Surely this could only get power from the alternator? and some sort of relay/kill circuit is shutting it all down.

I’ll check the leisure voltages when it stops pissing it down. Luckily I brought a spare van battery and charger so maybe two + the leisure will get us home?

Is the voltage at the leisure batteries staying at 14v even when the warning light is on and the starter battery is 12.4v? If so, give the earth strap between starter battery and chassis a firm tug. Also check the earth strap between engine and chassis.

Ah dodgy earth strap, had this snap on a old car, and when it does it used the accelerator cable as the earth strp, problem being theres a lot of power going through ther, so the outer melted and jammed open the accelerator and car shot off reving like mad, get an old batery lead and connect betwen engoine and a metal aprt of vehicle as a get you home jig, thats what the AA man did for me.

Thanks for all of that. One further bit of evidence

There is a PCB behind the seat which controls the charging of the leisure battery. I notice that when starting the fridge DC light goes on for 10 seconds then I hear a “click” then it goes off. Surely this could only get power from the alternator? and some sort of relay/kill circuit is shutting it all down.

I’ll check the leisure voltages when it stops pissing it down. Luckily I brought a spare van battery and charger so maybe two + the leisure will get us home?

That sounds like a VSR circuit (voltage sensing relay) it’ll disconnect the leisure battery when the voltage drops below a certain level (about 13.8V?) to ensure you have enough juice in your engine starter battery to start up the engine. If your engine starting battery is continuing to discharge after the VSR has disconnected it you have either an earth leak, or something staying on and draining the battery.

Right i’m going to assume 2 basic things:

1) the alternator is being spun fine by the engine (no excessive belt slip etc)

and

2) you can get to the alternator in the engine compartment

First, start and idle VAN, check if “charge warning lamp” is lit of not

With voltmeter, measure voltage on both the B+ terminals (the big one that goes to the battery) and the smaller ones (probably in a “multiconnector” maybe more than one depending on alternator spec /control.

The alternator is initially “excited” by the power coming from the ignition key via the warning light, however once it starts to generate power it can then “self excite” so there is no longer a differential voltage across the warning lamp, hence the lamp extinguishes.

if the lamp is coming on, this does suggest the alternator is faulty, and the regulator pack (most likely) is not maintaing the rotor magnetic field correctly (it’s going back down to earth (or close too) and hence the warning lamp is illuminating.

If there was a wiring fault downstream of the alternator in the main output wire to the battery, the warning lamp would not illuminate because the alternator would be maintaining it’s target output voltage (but at no current output).

However, if the alternator is loosing it’s EARTH, this can also cause funny things to happen, including putting the lamp out when it should be on.

I would find an auto electrician and get the regulator unit changed! In the mean time, all you can do if check the security of the terminals and mechanical fixings of the alternator and all the wires to the battery.

I don’t follow exactly what is happening with the PCB/fridge, but it should normally work like:

Engine stopped: No DC power to fridge. Leisure batteries isolated from starter.

Engine running: DC power to fridge, starter battery and leisure batteries linked.

Engine running with dud charging system: No DC power to fridge and batteries isolated.

If the charging system is a voltage sensing type, there will often be quite a long delay after stopping the engine before the batteries are isolated, as the starter battery voltage takes a while settle. Turning on something power hungry will normally drop the voltage sufficiently to isolate. When you start the fridge and get the click after 10 seconds, this could be triggering the relay to isolate, however it would only do it the once after stopping the engine.

Whilst fixing this, keep an eye on any fuses between the batteries and leisure charging system, as flat batteries at either end can cause a current surge and blow the charging fuses when cranking the engine or the alternator decides to work.

P.S DO NOT be tempted to start the engine and then disconnect the starter battery to check the alternator output. It can kill the alternator as it needs a load connected at all times when running.

BTW, if the alternator and regulator is functioning correctly, there should be pretty much always 14.4-14.7 v on the B+ output terminals at all times the engine is running, no matter what the load (flash your main beams/ heated windows etc on and off to check)

Also, the voltage regulator is built in to the back of the alternator, and can and do fail, they also can act funny when hot / cold etc

I have checked the charging fuses and they are fine.

maxtorque: when the light was off during the random working periods, the nearly flat battery was charged right back up. So the alternator is working during this period. When you saying losing it’s earth, is it not getting it from the chasis?

spooky: to be clear, I am not starting the fridge. I’m starting the van with the fridge set to DV charging, this normally keeps it working when we are driving as the power comes from the alternator. In “duff” mode, the light comes on as expected after we start the van, then we get the click and it turns off.

I guess I need to eliminate alternator fault once and for all. Which will mean getting a volt reading at source with the engine running. Not as easy as it sounds as it is behind and under the engine with a protective pan on the underside. I’ll try tomorrow in daylight.

THANKS for all of the suggestions so far.

How old / good is the battery? If it’s on the way out, or the electolyte is low, it could have a high internal resistance, which would drop the apparent voltage. I suspect temperature may influence this but am not an expert.

Is the fault the same with the spare battery fitted?

One other thought – being diesel, the engine doesn’t need battery for ignition, but it will use it for ECU. I guess you’re already minimising electrical load; driving in daylight where possible, etc? Empty the fridge and turn it off for the way home.

Modern diesels need the power for the fuel pump they really dont like having the battery taken out the circuit

Ran my old mechanical diesel for near 2 months with no battery just bumping it as needed and driving round and round till i could park on a hill…..

Had to replacd the battery and alternator though once i had money from summer job .

You say you have a spare battery?
It’s worth trying the other battery, it could be a battery fault (unlikely, but possible)
How far do you have to drive? 2 charged batteries should get you a couple of hundred miles + in daylight.
HTH
SmartMonkey

Well I hope it gets you home ok but if it doesn’t you can also draw the curtains and

“self excite”

I know this sounds obvious but you haven’t said you have checked ALL conections on the charging and earth side of the system,if theres any loose or bad contacts it will give the symptoms you describe.

Start at the battery,(for condition) and check the charging altenator and circuit/system from there..some great advice above..hth

Well, I just read that and thought the alternator was goosed, until the part where you said you had a new alternator fitted. Could the new one be faulty?

Don’t discount this, especially if it came from Halfords! Over the years I have had three electrical items duff from Halfords, each one caused a hell of a problem (condenser, rotor arm, battery).

Right I am going to run through all of that lot tomorrow in the daylight and report back. If we fix it then there will be a STW pub session for all involved on me, but self excitement will not be part of it.

Start to remove fuses one by one till you isolate the circuit with the problem…

Personally I’d isolate EVERYTHING bar the basic automotive circuits required to keep the vehicle legal.

I’m thinking iffy leads to the alternator, alternator faulty or something with the leisure side taking the charge from the battery. As said before, I would isolate the leisure side first and see if that makes a difference.

Just found this which could explain it all

As a few have said, I wonder if this earth is failing after the engine warms?

Earth fault, fit an extra earth lead Bart neg terminal to engine and body, low cost an likely to remove the problem.

Excuses the over top American style but this is a simple test to help find earth problems

Easy to check for earth fault Get one jump lead, clip one end to part of chassis (a metal bit!) and the other end to the alternator alluminium body, if this fixes it, leave it in place and drive home! (zip tie it up to stop it falling off)

However, with symptoms described, i’d be suprised if it were anything but a goosed alternator (the only real way the light can come on is for the alternator to become (un-energised) which requires a regulator fault

BTW, an engine earth fault is often also the cause of poor starting, as the starter motor earth current uses this to return to the battery during starting. So if your cranking performance is slow, even with a decent fully charged battery then the earth fault could be the issue. If the engine flys around on the starter fine, it’s unlikely to be the issue.

New alternator? I’d check all the connections to it. Are they tight? Did the person fitting the alternator crack the wiring? (Old wiring can fatigue snide the PVC cover so you might not know it)

14V sounds like alternator volts, while 12.4V sounds like battery only so a fortuitous contact that charges the battery / powers the system occasionally might well be the problem – it certainly was on a Cavalier we had in the 80s.

The earth strap issue is essentially the same sort of problem so I’m not discounting that.

I’ve no knowledge of motorhomes but seeing as it has a second battery, & I’m guessing a fridge too that probably runs while your moving; there must be a split charge relay somewhere that’s sending power to the second battery. These are designed to drop the charge to the second charging circuit when the engine revs drop to idling. If this failed the engine would be effectively trying to charge both the main battery & the second battery (which is being drained by the fridge). Had one fail when we were towing a caravan once. Cars battery was flat after a stop. A 12v fridge will flatten a battery in no time. I’d try & find the split relay, & also disconnect the fridge for the trip back.

I’m not an auto electrician and know nothing of motor homes but, logically,

The light comes on, which would indicate a charging issue rather than drain. It’s intermittent, so we’re looking at things like loose connections. The alternator has been replaced recently, so it’s unlikely but possible that’s the cause. You’ve tried different batteries, so we can probably rule that out.

I’d be looking at the multi-plug that connects to the alternator, as it’s plausible that this wasn’t reconnected properly when the alternator was changed. Or, the rectifier, which isn’t normally changed when you swap the alternator. Corrosion in the rectifier could readily cause intermittent charging issues.

Maybe.

Whereabouts are you in the Alps and why not use a local mechanic? The French go nuts for motor homes so it stands to reason that there might be some good mechanics around. I have a few mates with motorhomes in the alps and can ask them if they’ve any recommendations if you like? Just depends on where you are.

there must be a split charge relay somewhere that’s sending power to the second battery. These are designed to drop the charge to the second charging circuit when the engine revs drop to idling.

If it does that its set incorrectly, it should only turn off when the engine is stopped. The different in voltage between idle and driving is often only 0.1v and turning on the headlights or similar could easily make the split charge think the engine had stopped.

The only detrimental effect the split charge/leisure side could be having is if the leisure battery has a bad cell or two, but then the split charge would constantly cut in and out.

(Local mechanics also like screwing over stranded holidaymakers who are affluent enough to be driving a big motorhome! Not all of them, granted)

Update: I think we are sorted.

Today I removed the earth strap from chasis to gearbox, this was a joke, a braided pile of crap that had corroded and was loose as hell. I used a battery neg cable in its place and the problem has gone away.

I’ve bought a temp cable setup from the local auto shop which should get us home. Then I am going to fit a proper earth strap that has some protection from the elements.

I owe everyone on this thread who mentioned earth problems a fair few pints.

Thanks again
Dave

Glad you’re sorted! The braided earth wire was the first thing I thought of because it happened on our fiat camper. Ours was so bad it killed the alternator and boiled the battery. The van stunk!

Woohoo! Bet you are glad you gambled rather than turning round and getting the ferry straight home.

Today I removed the earth strap from chasis to gearbox, this was a joke, a braided pile of crap that had corroded and was loose as hell. I used a battery neg cable in its place and the problem has gone away.

As one of the ones who mentioned this, also check your acceletator and clutch cable as mine melted after taking the load off the earth strap and accelerator stuck open, as i ve previuously said.

The cable doesnt melt as such but the outer sheath does and causes the cable to stick in the sheathing.

The accelerator is probably electronic via the ECU, i.e. no physical cable. Clutch almost certainly hydraulic too.