Wierd electrics

Evening all!
Just got home with our first campervan a 1999 Duetto, travelled from Yorkshire via Ashbourne and Ebury Hill as a shakedown and here are our findings so far, van is an auto and drove very well although doesn't like hills unless you can get a good run at them!
So spent today trying to get to the bottom of some electrical gremlins that were revealed e.g. the fridge will only work on 12v when driving as soon as you shut off the engine the 12v to the fridge goes off.
There is no 12v supply to the control panel with the engine off but when the hook up cable is connected the 12v is present so as things stand we must have a hook up or else we have no fridge, water heater or water pump so no shower.
There are 2 batteries fitted under the bonnet, however, contrary to the handbook they are both starting batteries, there is no split charging relay present but the installation appears to be factory so doesn't appear to be someones "improvement"
The positive cable from the nearside battery goes down and over the bellhousing to the starter motor, the cable then continues up to the other battery, the connection at the starter motor is an inline fitting through a moulded plastic fitting which I think can only be OEM.
The drivers side battery is April '21 fit so quite new but the one in the passenger side is old and finished, quickly drops to about 11v when disconnected so I've left it disconnected as it was pulling the other battery down.
A PO had fitted a solar panel with leisure battery which was only powering a retro fit Chinese diesel heater which I have removed today as the internal fuel tank was stinking out the interior not good! I am in the process of connecting this battery to a cigar lighter type socket and a double USB socket with voltage display which was already fitted but connected to a cable which came live with the hook up but the cable fitted would be rated at maybe 0.5A so have terminated this safely, whoever did the previous installation thought it OK to twist wires together with a bit of tape so will need to go through the electrics thoroughly and eliminate any more that I find.
A second leisure battery had been fitted in the locker under the cooker but this has gone AWOL, this was connected via cables under the floor to the other leisure battery under the seat on the nearside, there are 2 relays in this locker which are next on the investigation list to determine how they were supposed to do.
Sorry it's a bit long but wanted to get all the details in first time.
Graham

Welcome to the forum
Phew long intro.  It is quite normal for the fridge to work on on 12v only when the vehicle is running.  Whilst stationaryits gas or mains if you are on EHU.  AS used the 2nd battery under the bonnet as a leisure battery on some models.
Think you will need more investigation to establish what supplies what.
There a quite a few of those vans on here so hopefully someone will be more help than me.

Micky

Hello and welcome to this most friendly and informative forum. 

Roli is absolutely correct. The appliances you list would drain a battery in no time at all if running direct on 12v. Gas or EHU is the way to go.

And... just to confirm your assumption that the two batteries under the bonnet are "twinned" from the factory - yes, that's correct. That's how Ford wired them on a Mk.5 with auto box.

Hi Graham.
I have learn from our own recent issues with electrical issues that issues with relays are sometimes to fault.
Check your relays first and see what the outcomes are as if it is this, then they are cheap enough to replace.

Bob.

Roopert wrote:And... just to confirm your assumption that the two batteries under the bonnet are "twinned" from the factory - yes, that's correct. That's how Ford wired them on a Mk.5 with auto box.

That makes sense as being Automatic you can't push start it, thank goodness a fellow camper had a set of jump leads when the Chinese crap radio refused to switch off and drained the battery!
I'm going to link the starter batteries to the leisure batteries via a split charge relay for charging on the road then the solar panel will help to keep them topped up when stopped.
I'll be checking the relays to figure out how they are supposed to function and make sure they are sound, fortunately as a retired marine engineer electrics don't phase me, in fact I quite enjoy a challenge!
Thanks
Graham

Grabea wrote:I'm going to link the starter batteries to the leisure batteries via a split charge relay for charging on the road then the solar panel will help to keep them topped up when stopped.

A conventional split charge relay won't do that (it's one-direction only), but a VSR will.

We fitted a Victron Cyrix unit to the Trooper, in place of the relay fitted by A/S at the factory, and it works well - costs about £40-45.

Been doing a bit more digging today in the locker under the oven, removed the back panel to gain access to the charger which checked out fully working so that's one less thing to worry about.
When I said split charge relay I meant a VSR which I've already purchased and will be fitting it tomorrow when a second leisure battery should be delivered.
There are 2 relays and 2 fuses mounted on the back panel which seem to function as follows:-
Both relays get a 12v signal from a green wire when the engine is running which energises the relay coils so with engine off the charger feeds the leisure battery via the c/o relay, 30 to 87a so that part seems to make sense.
The problem I have is that both wiring diagrams I have don't apply to my vehicle as it is an auto i.e. 2 batteries under the bonnet both for starting, presumably this is as you can't push start an auto so doubles the starting battery capacity.
87 on the c/o relay goes through a 20A fuse to a red wire fridge supply? live when engine running.
The other relay, I think, charges the leisure battery from the alternator when the engine is running?
I guess I could replace this relay with the VSR?
Thanks
Graham

I have a 1998 Ford Auto Amethyst so the same front end on a chassis cab. I'm not sure the fully twinned batteries are specific to the auto, just Ford gave up on the complication of the accessory battery idea.

Before that both batteries were still connected to the starter motor via a special 3 terminal solenoid. When you turned the key all 3 terminals were shorted feeding both batteries to the starter motor. Drop the relay once the engine is running separated the batteries and Fords own split charge relay kicked in to charge up the accessory battery.

Business operators being cheapskates would only replace batteries one at a time and it was the primary that would fail 1st. Once the accessory did fail when you tried to start the primary would be trying to boost the accessory battery as well as start the engine somewhat unsuccessfully. So much so that operators found that if they disconnected the accessory battery the engine would start and couldn't understand why.

AS being cheapskates were until the change using the accessory battery as the habitation battery. Once the batteries were fully paired they couldn't do that without discharging the starter batteries. I wonder when they found that out?

One relay is the split charge relay to charge the habitation battery the other is the changeover relay to stop the 12v services working with the engine running and enable the fridge to run off the alternator. So one is 4 terminal, the other 5.

My Power Supply (I will NOT call it a charger) was also hidden behind the cupboard back panel with a hole to stick your finger in to turn it on/off, the idea of blindly sticking my finger in a hole knowing there is 240v AC mains somewhere in there does not appeal to me .

When I took the panel out to work on the rear lights I found the frame to fit the panel where it should be further back was still there so I took the opportunity to use it. The battery is now turned around, the PSU is where I can see it and I have space for a second habitation battery if I so desire. If I do sell it I will stick up a warning that ONLY sealed maintenance free batteries should be fitted and the vent pipe MUST be used

Second habitation battery installed and charging from the solar panel so tomorrows job is to run the cables under the van between the two habitation batteries and install the VSR and I should be complete with the habitation electrics.
Second starting battery will be replaced when it arrives, probably Monday then we'll be good to go.
Graham

One of the things that you may need to think about is current surge (or more accurately, initial current peak). The issue here is that with a VSR (or simple split charge for that matter) you will be placing the load of four batteries on the alternator.

This shouldn't be an issue in mid-summer, but let's say that the van has sat for a week or so in midwinter when you've had little sun and low temperatures which make battery self-discharge worse.

You then have a difficult engine start (glow plugs running for max time due to the cold, thick oil, etc) so when the engine starts the alternator will have to charge four part-depleted batteries, while also supplying all of the winter vehicle loads such as lights, wipers, HRW and blower. This is likely to be a very high load on the alternator.

If it were mine, I would think seriously about adding a longer delay (a VSR will typically have a built-in delay of maybe 10 seconds), giving the alternator several minutes to bring the voltage of the engine batteries up, before the leisure batteries get added in.

You may have a similar issue with the mains charger, because the VSR will connect all four batteries together when it detects the mains charger being turned on. This should be less of an issue because you won't have any of the vehicle loads present, but I suspect that four batteries may exceed the load rating of the charger in a typical late 90's A/S installation if some or all of them are part-discharged.

Valid points so will have to see how it goes, battery charger output is still fused so that will pop if load is too great, leisure batteries charged fine just on the solar panel so maybe that will keep them topped up during idle periods and prevent excess draw on alternator?
Will see how it goes and update later.
Graham

Hi  

As far as the charger is concerned (I'll call it a power supply as that's what it really is):

Grabea wrote: battery charger output is still fused so that will pop if load is too great

Not if it’s the original Zig it won’t. The Zig will just sit at the current limit whether it’s connected to one battery or ten. It’ll just stay in current limit (about 12A) for longer. You can’t overload a Zig.

It may get a bit warm but it will be fine if there is enough ventilation. If it does over heat there is a temperature cut out that will operate and reset when it cools down.

Brod

If you connect multiple batteries together which weren't previously then the 1st thing that will happen is they will have to equalise the voltage between them which will be instantaneous. This will be achieved by a high battery delivering current to a low battery, this collapses the voltage of the high and raises the low due to the internal resistance. This current can blow the fuse especially if the difference in the state of charge is large.

The internal resistance of the alternator is such that in comparison to the batteries dumping current into each other it won't be of major significance. Assuming the solar panels have maintained the leisure batteries at full charge after a few seconds the alternator will feed current into the starter battery off loading the leisure and all 4 will rise up to the regulated output of the alternator.

Thanks all, will continue to monitor system and see how it copes.
Graham

Another complication arises because you have multiple batteries equalising with the same. Although at one level batteries paralleled can be treated as one it is not an absolute rule. You cannot do anything about the vehicle batteries but each of the leisure batteries should have a separate fuse at least

HairyFool wrote:Another complication arises because you have multiple batteries equalising with the same. Although at one level batteries paralleled can be treated as one it is not an absolute rule. You cannot do anything about the vehicle batteries but each of the leisure batteries should have a separate fuse at least

Yes that's how they're connected via a separate fuse box, got a neat one from Amazon with an led for each fuse which lights up if the fuse pops!
Graham