12 volt power

[wotme]

I've just been looking at a MHs basic 12v wiring diagram and from what I can make out the leisure battery is charged as well as the van battery when travelling.
Would this be the case for my 2007 Elnagh coach built or are my wires completely crossed again

 

[Spriddler]

I take a pragmatic approach.
Check the leisure batt voltage with the engine stopped and again with the engine running when you should get a higher reading. The engine must be rev'd sufficiently for the dashboard ignition light to be out.

 

[Duck Truck]

depends on the set up
I think our van does
and our old van had an aftermarket split charger
when the engine battery was fully charged
then the leisure batteries were then charged

 

[Eddystone]

I agree. Check voltage of each battery before starting the engine then again with the engine running.
Brian

 

[pappajohn]

I would be very surprised if it didn't charge the leisure battery on a 2007 van but don't expect anything startling....it won't recharge going 15 minutes round the block.
If the battery is reasonably discharged it could take many hours driving to charge fully and if its a gel or AGM battery it never will fully charge.

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[Spriddler]

I notice from your Profile it says you are 'Just looking' although in your post you say you already have a m/h. Either way it's useful to make the checks suggested.

 

[autorouter]

Yes, in most motorhomes the leisure battery and the starter battery are charged by the engine alternator while the engine is running. That means they are connected together. But when the engine is stopped, you want them to not be connected, for many reasons.

First, if you run the leisure batteries flat, you want the starter to still be able to start the engine. Also, remember that the starter motor takes a huge current for a few seconds when starting the engine. Look at how thick the wire is from the starter battery to the starter motor. You don't want to be taking that kind of current from your leisure battery along those thinner wires.

Because of this, there is an electrically operated switch (a relay) that disconnects the two batteries when the engine is stopped. There is a wire from the alternator that is powered when the engine is running, usually called the D+ wire. This is used to switch the relay.

Spriddler gives you an easy way to check that this relay function is actually working correctly

 

[wotme]

Thanks for the tip spriddler and yes your right about my profile, I'm trying to find out how to edit same.