# Help needed: Understanding my electrics! 1989 Hymer B544



## Watoh (Jan 31, 2015)

Hi folks, 

I've been putting this subject off for a bit.. but i need to bite the bullet and figure out my electrics.  I'm starting from a real position of ignorance, it's my 1st motorhome and to be honest I'm not sure how it is meant to work.

Present situation: 
Main engine battery works as expected, charges well, holds charge and does not get run down by the habitation area.
Leisure battery charges off the running engine only, does not charge when hooked up to the mains.
When on mains hook up the entire habitation area runs off 240 volts.  There is a RCD in a cupboard in the habitation area.

Under the drivers seat is a "battery charger" labeled: Elektromatic LA 110 Batterie-Ladegerat made by Schaudt.

See image below

 

Here is where something is amiss.  There is a black cable from the engine compartment that goes to the front of this box (the blue & brown cables seen above).
There is another cable that comes from the back of the charger and plugs into the white socket you can see in the picture. From this socket, the white cable goes to the leisure battery compartment with a 3 prog english plug that is NOT plugged into anything, there is nothing to plug it into.  It would seem something is missing!

The leisure battery has a single cable connected to either terminal.

Can anyone explain this mystery of motorhome electrics please!  I'm quite confused!  I suspect it has been 'modified'.  :idea:

Thanks for any help, i hope I have been clear in the present setup.

Cheers.


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## K9d (Jan 31, 2015)

This is exactly the same as my charger, there should be a lead to the mains plug, 2 pin in your case, and the blue and brown lead should go to the leisure battery. It sounds like your have been rerouted to the engine battery.

I would have a look at the engine battery to see if there are extra wires attached to it.

The other possibility is that a fuse has blown or the charger isn't working.

Having another read of your post it sounds like the white lead should get power form the 3 pin plug, can you plug that into an extension lead to see if you get any power.
Am I correct it goes Charger-2 pin plug/socket-3 pin plug ?


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## GRWXJR (Jan 31, 2015)

If I  read your text correctly.....

The plug next to the charger in the white box is a Euro 2 pin AC input to the charger.

This in turn is being fed by a UK 3 pin plug on the end of the white cable, which you say isnt plugged into anything.

It sounds like this charger cant work as its not plugged in!

You can plug it into one oc the van AC sockets which should in turn have juice off your EHU to get it power, or run an extension lead out and plug the plug intk that.

Sounds like it might be just that simple  if you are lucky!

G.


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## Watoh (Jan 31, 2015)

K9d said:


> Having another read of your post it sounds like the white lead should get power form the 3 pin plug, can you plug that into an extension lead to see if you get any power.
> Am I correct it goes Charger-2 pin plug/socket-3 pin plug ?



WOW WOW WOW talking about a brain fart!  

Plugging the english 3 pin plug (that is not connected to anything) into a socket in the habitation area could in theory complete the circuit and allow charging from the mains.  Jesus wept, if this is all that was needed i feel very very silly!

Even though i'm in the middle of cooking and it is horrid outside I'm gonna have to check this now!

Will report back.


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## Watoh (Jan 31, 2015)

GRWXJR said:


> It sounds like this charger cant work as its not plugged in!
> .



Yes I'm feeling very silly! 

I've only had it since June!  i hate electrics!


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## GRWXJR (Jan 31, 2015)

Dont worry! Feeling silly is free!

Much better than spending bucks on a diagnosis / fix!


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## Watoh (Jan 31, 2015)

GRWXJR said:


> Dont worry! Feeling silly is free!
> 
> Much better than spending bucks on a diagnosis / fix!



Well I might need that too!

When plugged in the main RCD in the house is tripping! 

I'll have to have another look tomorrow in the light... seems something is amiss.

Any ideas what to look at that would cause the RCD in the house to trip?


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## K9d (Jan 31, 2015)

Watoh said:


> Yes I'm feeling very silly!
> 
> I've only had it since June!  i hate electrics!



We all have moments like that


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## K9d (Jan 31, 2015)

Watoh said:


> Well I might need that too!
> 
> When plugged in the main RCD in the house is tripping!
> 
> ...



So when you plug the 3 pin plug in it trips the RCD inside ?

I take it the RCD doesn't trip when the EHU is plugged in, only when the charger is plugged in.

I would check the 3 pin plug, assuming that's fine unplug the 2 pin plug and plug in the 3 pin plug, if the RCD doesn't trip that part of the circuit is OK. Then plug in the 2 pin plug if that trips the RCD then I'm guessing the charger is the issue.

In mine there is no 2 pin plug, someone in the past has wired it direct to a 3 pin plug and fitted a socket under the seat.


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## Watoh (Jan 31, 2015)

Thanks k9d, i'll do some routing about tomorrow.  Thanks for the help, its much appreciated.


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## GRWXJR (Jan 31, 2015)

Watoh said:


> Well I might need that too!
> 
> When plugged in the main RCD in the house is tripping!
> 
> ...



The Euro is 2 pin, so theres no earth electrode.  Its a stab in the dark, but RCDs look for any kind of earth leakage or potential difference to earth so I  wonder if its just that the charger isnt earthed?  Might be worth taking an earth lead from the body of the charger unit and bolting if to a good chassis earth and see if that does the trick, as well as making sure all the connections in the plugs are correct and tight (with it unplugged of course  ).


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## Canalsman (Jan 31, 2015)

I would urge extreme caution when dealing with 230v connections.

The house RCD is tripping - this suggests there's a fundamental fault.

*Consider consulting an electrician before you injure yourself and/or damage the vehicle!*


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## GRWXJR (Jan 31, 2015)

POI Admin said:


> I would urge extreme caution when dealing with 230v connections.
> 
> The house RCD is tripping - this suggests there's a fundamental fault.
> 
> *Consider consulting an electrician before you injure yourself and/or damage the vehicle!*



I do agree with the above.

I'd add though that as you had no rcd trip issues on ehu before you plugged in the charger, this strongly indicates that the problem is isolated to the charger circuit.

Ok dont mess with it if youre clueless, but this at least gives you an area to start the fault finding at.

Bear in mind the charger might have been left unplugged as the previous owners found the same problem and simply disconnected the charger instead of getting someon to fix it!

I realised after posting this, that  you didnt say that the rcd tripped instantly when you plugged in the charger?  If it took a short while to knock the trip off, the Odds that its a faulty charger unit get higher (as the charger warms up and the resistances change internally its exacerbating a fault enough to trip the rcd).

G.


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## piman (Feb 1, 2015)

Hello Watoh, 

the plug from the charger that goes to the white socket, is it two pin with a hole and does the socket have two holes and a pin? It is possible that the charger has some earth leakage and I don't believe it would have been installed without an earth to the case, as it is metal. But it is possible that the charger to plug and socket to the U.K. plug has been cross wired? no earth won't cause an rcd to trip but connecting a neutral to earth will. Without any test equipment, I would rewire the charger directly onto a U.K. plug, i.e. remove the original two pin plug cable from the charger and connect the three pin plug lead directly (Ensure the earth wire is connected directly to the metal case). Try again and if the rcd still trips then there is a charger fault.

Alec


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## Deleted member 5816 (Feb 1, 2015)

If the charger has NO earth connection there cannot be a leakage to earth so the RCD would not trip 

( the case could be bolted to the chassis so could be earthed that way ) 

But if the cable to the charger is only 2 core it would indicate the unit is Double Insulated and requires no earth ( unless cable changed wrongly )

Alf




GRWXJR said:


> The Euro is 2 pin, so theres no earth electrode.  Its a stab in the dark, but RCDs look for any kind of earth leakage or potential difference to earth so I  wonder if its just that the charger isnt earthed?  Might be worth taking an earth lead from the body of the charger unit and bolting if to a good chassis earth and see if that does the trick, as well as making sure all the connections in the plugs are correct and tight (with it unplugged of course  ).


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## Polar Bear (Feb 1, 2015)

When testing for faults it helps if you only test one thing at once. IE; charger or socket!
You could try testing the two pin socket with something like an electric tooth brush or other two pin adapter gadget to ensure that this is working. 
If that works okay then the problem is in your charger. 
If the electric tooth brush/gadget does not work/trips out consumer unit try cutting off the two pin plug and replace with an English plug and try it in an extension lead.
There is usually a reason that things in campers are not plugged in and that's because it's scrap!


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## piman (Feb 1, 2015)

Hello Alf, 

"If the charger has NO earth connection there cannot be a leakage to earth so the RCD would not trip "

That is true of original earth leakage breakers but modern breakers are residual current and measure the current in and the current back and if the difference is more than 30mA (domestic breakers) then it trips, an earth is not required. I also doubt if it is double insulated as it has a metal case. 

Alec


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## Deleted member 5816 (Feb 1, 2015)

Hi Alec so with your therorie where dose the leakage go if the item does not work there is no leakage.
For a modern RCD to trip it must sense a imbalance that imbalance is why they are loosely referred to as Earth Leakage Trips  

so no leakage  =  no imbalance  =  no trip.

Most RCD trip at about 27 / 28mA in total any leakage below this figure will not trip. 

The first generation of Earth Leakage Trips were voltage operated  and required a voltage of 40 volts to trip, subsequent generations of trips have all been current balanced types

As I said could be wired wrongly.  ie working live to earth. remote diagnose I very difficult and fraught with trying to understand the OP.



piman said:


> Hello Alf,
> 
> "If the charger has NO earth connection there cannot be a leakage to earth so the RCD would not trip "
> 
> ...


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## piman (Feb 1, 2015)

Hello Alf, 

I think we are slight cross purposes, I was only referring to an earth connection in the charger cable. I would anticipate a connection between the charger case and the van chassis and also a bond between the incoming mains to the chassis.

I haven't heard anyone call them earth leakage breakers for many years, by the way. 

Alec


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## Deleted member 5816 (Feb 1, 2015)

this does not follow from your previous post I do not follow how an Earth connection is not required, as you stated in your previous post

_That is true of original earth leakage breakers but modern breakers are residual current and measure the current in and the current back and if the difference is more than 30mA (domestic breakers) then it trips, an earth is not required. I also doubt if it is double insulated as it has a metal case. _






piman said:


> Hello Alf,
> 
> I think we are slight cross purposes, I was only referring to an earth connection in the charger cable. I would anticipate a connection between the charger case and the van chassis and also a bond between the incoming mains to the chassis.
> 
> ...


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## Watoh (Feb 2, 2015)

Thanks all for some great suggested things to look at.

Don't worry, I won't be applying for a Darwin award.. I might find electrics annoying but I won't let them kill me, I know enough to keep myself safe! 

I've got some time today to do some fault testing.  I can't say if the RCD was tripping straight away, but i'll do some looking today with the MH by the front door with some daylight.  Will report back.  Ta.


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## Watoh (Feb 2, 2015)

Well that was enlightening!

Just had a really good root around the hab electrics.

The unplugged English 3 pin plug was a complete red herring!  It was not the power inlet for the charger but a random two plug extension that had been run from the back cupboard to the leisure battery compartment.  I think it must be to allow a 12 volt to 240 volt converter to be but onto the battery and then this plugs into it to give so 240 volt in the rear when on battery.  A complete red herring.  (I was only able to see this after removing all the electrical ducting)

The tripping RCD is also a false led.  My fridge trips the mains when on 240 volt, an already known issue, somehow it was switch on hence causing the trip. (* looks at wife, she must be to blame!)

Bottom line is, the battery charger is wired in... and i think it's charging... but very slowly.  I'm the middle of testing it.  It seems odd as 2 months ago the leisure battery was dead and after 24 hours on mains was still dead, so I concluded it was not charging. 

I did find and fix a loose earth connection on the 240 volt circuit, not sure if this has any bearing.  But good to find none the less.

Sorry for wasting people's time.

I do have a question:  Is this leisure battery charging just a trickle charger?  The output seems very low.


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## piman (Feb 2, 2015)

Hello Watoh, 

yes, I would expect that it only gives a few amps, so takes some time to fully charge a battery especially if allowed to become really discharged.  (To be avoided if possible as it's detrimental to battery life) It's not good to force charge a battery, again, it knocks some of the life out of it.

Alec


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## GRWXJR (Feb 2, 2015)

The output Amps is often written on the dataplate or the body of the charger somewhere, and normally refers to the output rating.

Lots of trickle chargers are rated at 5A which is sufficient to maintain a battery of up to 100AH that hasn't been pounded, but a really and ideally a charger rated at 10% of the total battery capacity to be charged is a good thing to have.

I have a 5A in my van (happened to have it lying around off a scrapped emergency generator control panel so it made sense to hard wire it in).  I also have a portable Numax 10A Intelligent Charger with a bit more spuds in it.

I am not familiar with your type of charger so have no idea what its output is, but you can probably google it easily enough.


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## K9d (Feb 2, 2015)

The charger is rated at 7A, I've never had a flat battery on mine so not sure how it would cope with a flat battery.
I have noticed that when mine is on and the battery is fully charged the meter above the kitchen will flicker from 0 to slightly above as if the charger is pulsing.
Does your meter show charge going into the battery, what voltage does the leisure battery read OFF charge and then ON charge ?


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## Deleted member 5816 (Feb 2, 2015)

If you have let the LB battery go flat you will have difficulty charging from the on board charger take it of and try a garage to give you a booster charge.
You may find you need , a new battery

Alf


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## Hymie (Mar 21, 2016)

[No message]


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