Leisure battery not charging from engine.

!996 Harmony......Suspecting that the leisure battery was not charging from the engine, and following advice on here, we looked at the 2 fuses near to the battery.  Apparently, one is for the fridge and the other for the leisure battery.
Both fuses were green in colour and marked 30amp.  One was fine, the other was indeed blown with one 'blade' charred and the holder looking a bit suspect.  We duly changed this for one of the same, although it was difficult to replace.  
Don't know how to tell if it is now charging, without going on a long run, but the voltmeter that we plugged in goes off when the engine is running on idle.
More puzzling is the fact that the fridge light no longer comes on when changed to 12v and the engine running.....this was working fine yesterday!
What have we done wrong?

first thing I would do is check the fuse again. If the leisure battery voltage is too low you can get (depending on your charging system) a current rush at start up that can blow the fuse again.

If it has blown again, or your LB voltage is low I would suggest charging it from the mains first before replacing the fuse. It may be sensible to do that anyway.

Momac wrote:but the voltmeter that we plugged in goes off when the engine is running on idle.

That would depend on what you plugged it into, but in general for that year you would expect the controller to shut off power to habitation circuits while the engine is running. If you connect the voltmeter directly to the battery you should see whether it is charging or not.

The points that dbroada makes are all relevant. In addition, it would be worth checking that you have re-inserted accurately any fuses that you removed - unfortunately on some fuse holders it is possible to misengage the fuse in the housing. Also, if the damage to the fuse holder is bad then I would definitely have it replaced - the holder should only cost a couple of quid or so.

Thankyou both.  The leisure battery was already charged up from EHU and then run down a little, but showing 12v at rest. That makes sense that the controller has shut off power to habitation circuits when the engine is running. We have checked the 'good' fuse again and it seems OK...they are both the blade type that can only go in one way really.  
We still have 2 problems.....the fridge is still not working on 12v with the engine running, and we have no way of knowing whether the battery is charging, or even which fuse controls which?  They are both the same wattage (which I think is wrong anyway) and they are both on the live side of the battery, although one has red leads and the other black leads.  The one with black leads looks newer than the other....maybe it has been changed and came with black leads? 
I have ordered 2 new fuse housings from ebay....just have to figure out how to fit them, then see what works.

There should be a relay which switches the fridge and battery supply on when engine is running. Worth a check.

Where is that likely to be, please?  And what does it look like? Thanks

Sorry can't help, don't know your base vehicle. Somebody who knows will be along shortly.

There is a thread in this forum from a couple (or more) years ago in which a member produced a very clear and simple diagram with accompanying photographs of relays to show how this section of circuitry works. I can't find it and we are awaiting the imminent arrival of overnight guests so if anyone else can find it......

If Momac has not resolved his problem by then I can produce something tomorrow afternoon.

Momac wrote:Where is that likely to be, please?  And what does it look like? Thanks

Have a read of this thread (Symphony and Harmony should be wired the same)..


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Some more info at link above, don't worry that its not the same van.

Is this any help?
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It does.

In this instance RL2 is a split charge relay and RL1 the fridge relay. However in many vans RL1 will be a changeover relay with pin 30 connected to the leisure battery +ve, pin 87a to the habitation equipment and pin 87 to the fridge. The effect is that when the engine is off the leisure battery is connected to the living area equipment but when the engine is started the engine battery is connected to the leisure battery and them both to the fridge, the living area equipment being disconnected.

The D+ fuse will be 5A but the others will probably be 20A (on mine 40A).

The split charge relay will usually be rated at 70A and the fridge relay at 40A but...

OK....so far - put in new leisure battery, put in new relays under seat next to battery, replaced fuses from main battery.  Still no joy...battery not charging from engine, fridge not working on 12V.  Getting desperate now.

Well there's no real substitute for a complete methodical check from battery/alternator through to the load at the other end, but if both relays are failing to close I would check that terminal 86 (might be 85 - you can connect the coil either way round) on each relay goes to +12V when the engine starts, and that there is a good earth connection on terminal 85 (or 86 if the coil is "reversed").

Still no joy on this.....we had Moran's of Ludlow look at it for a couple of hours last week.  After much probing and testing with meter, he said we had 14v on the relays but only 13v on the leisure battery with the engine running.  He also replaced fuses, tested everything, and could not solve the mystery.  There is a small box next to the leisure battery called 'Battery Mate' with a green light glowing all the time - engine running or not.  He didn't seem to know what this is....can anyone enlighten us on this one?  Could that be part of the problem?

The Battery Mate is an electrical circuit that allows the transfer of energy from the leisure battery to the vehicle battery whilst the leisure battery is under charge by the on-board mains charger or solar panel.

Any competent electrician would know that the reduction in voltage in a circuit is caused by the current flowing through a resistance in the circuit so somewhere between the split charge relay and the battery terminal there is a resistance causing at least one volts drop. The cause could be any connection or component in the +ve or -ve circuit and the only way to find it is to work through the wiring and components element be element. Its simple stuff but may he hard to locate the exact cause.

Thanks Peter.  Yes, I think he did realise that, but still couldn't find the cause. Basically, we ran out of time in the end and had to move on....he didn't charge us anything!  I have contacted West Country Motorhomes service division and am just waiting for a reply to see if they can help. If you, or anyone reading this, know of a good motorhome electrician in our area who could help please let us know....we tried a mobile caravan chap who, quite frankly, seemed to know less about the system than we did! We are based in Honiton in Devon, half way between Exeter and Taunton and don't mind travelling 30 or 40 miles or so.

Sorry I have no experience in your area but I'm sure some members will.

Could Chelston not help?

I have contacted Chelston by email.  Westcountry Motorhomes replied to say they only book vans in that are purchased from them.

It could well be TOTALLY irrelevant but on my Hymer which was fitted with a Schaudt charger unit there were two 50A fuses in series in the charging circuit for the habitation battery. One was located by thevehicle battery and the other close to the habitation battrey which was under the passenger seat.
On a couple of occasions i unwittingly tried to start the vehicle when the vehicle battery was discharged. On thetwo occasions one of the 50A fuses blew - a different one each time - as the starter motor tried to take current from the habitation battery.

There is the possibility of a blown fuse but that does not easily reconcile with the 1 Volt drop between the relay and the Habitation battery. To me that says that the Battery Mate is feeding some amps back to the vehicle battery. You could try disconnecting that box but do be careful to disconnect the blacks on both batteries before you fiddle with the battery mate or you may see some spectacular sparks!
Another possibility is that the wire from the relays to the battery and the fridge are considerably under-rated.  They should be around 5mm thick with their insulation at a guess.  if they are much less they will cause voltage drop.
But you have two independent problems as the fridge has stopped working as well!
As Peter said - you just have to follow each wire - and do look out for any signs that cables have overheated. If they are light the battery mate may have tried to charge the vehicle battery from the habitation with a current more than the cable could take.
This is all guesses i am afraid.
Good luck

Hooray!!!! It's fixed! By 'the best Auto-electrician in the world'(as described by the bloke who gave us his name).  It took him less than 10 minutes to find the fault, and 10 minutes to fix it...a small wire (purple coloured) from the alternator connected by a failed Scotchlock.  He disposed of this and soldered the connection - quite an awkward job involving lying underneath the van - and, lo and behold, all working again! 
Bear in mind, this was the third so-called expert to look at it.  If you are anywhere near Exeter and require a fast, confident job contact Kevin Blackmore of Rhino Auto Electrics (mobile).

Ah yes - Scotchloks - a curse on any electrical installation. I guess they may be Ok for anything fully protected from roadspray, but they are a real liability anywhere underneath or in the engine bay, because they penetrate the outer insulation of the cable but don't then protect it from water (or salt water in the winter) entering the core. Personally I don't think any professional installer should even consider Scotchloks in that situation.

Momac wrote:Hooray!!!! It's fixed! By 'the best Auto-electrician in the world'(as described by the bloke who gave us his name).  It took him less than 10 minutes to find the fault, and 10 minutes to fix it...a small wire (purple coloured) from the alternator connected by a failed Scotchlock.  He disposed of this and soldered the connection - quite an awkward job involving lying underneath the van - and, lo and behold, all working again! 
Bear in mind, this was the third so-called expert to look at it.  If you are anywhere near Exeter and require a fast, confident job contact Kevin Blackmore of Rhino Auto Electrics (mobile).

Where i live there is an auto electrician who fits that description to a tee! Exactly the same sought of guy. Works entirely single handed, 8am - 6pm six days a week, from a tiny garage down a back street in a local town. Never advertises as his customers do that for him! Many garages use him as they know how good his work is. Once you find a guy like this you don't even bother looking elsewhere.

He recon'd a starter motor on a previous Transit i had. He's only a small chap and i thought he'd take it out from underneath but no, he simply lifted the bonnet and launched himself into the engine bay, legs dangling (!!), and whipped it off in minutes! A few minutes later he had the recon'd motor back on...no messing! 

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Oh and that red Audi TT is his which he's owned for years yet it looks like it's just left the showroom!

My R reg Trident bought second hand 5 years ago has not got a leisure battery but an ordinary car battery. The previous owner gave me some long explanation about amps etc which I don't really understand. The whole 12v habitation system is now not working. The red/green light does not come on at all now. All fuses that we can find have been checked. Can anyone shed any light on this.  Should I in fact have a proper leisure battery? Anyone know of a good auto electrician in the Newmarket/Cambridge area?