B2B wiring?

[Ronaldo]

Hi All. I'm a newby to Fun. I've just fitted a Renogy DC to DC charger to my 2006 Elddis Suntor 120.
Two questions please.
1) Do I have to disable the existing split charge relay?
2) If so how do I do it? I attach pic of my leisure fusebox. Is it just a case of pulling a fuse? If so which one!?
Cheers
Ron

 

[Pausim]

Hi Ron.

The answer to 1) is yes. If you have connected the B2B directly from the engine battery to the leisure battery you will need to disable the split charge relay. I don’t know enough about your motorhome to answer 2) properly but it might be worth pulling the fuse marked VAN BATT+ to see what happens. I assume this fuse is for the connection to the engine battery, you may lose some functions but hopefully it would break the loop.

 

[Ronaldo]

Thanks for your thoughts. I was also thinking the same fuse! I'll give it a go and see what happens.

 

[JockandRita]

Come back here and let us all know please.

Good luck achieving the disconnection, without losing other functions.

Jock.

 

[Tombola]

Good answer above...
Sometimes the same fuse controls things like step or some fridge functions...have a good check once done. Be v interested to know your findings it will certainly help others with same setup in future.

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[Guigsy]

I've got a 30A Votronic B2B. I've kept it that low because the existing wiring will cope. So it can just sit between the cab battery and the EBL without disabling anything... that's the hope anyway.

 

[Pausim]

I've got a 30A Votronic B2B. I've kept it that low because the existing wiring will cope. So it can just sit between the cab battery and the EBL without disabling anything... that's the hope anyway.

Ronaldo doesn’t have an EBL and the 15A fuse in his picture suggests a much lower wiring/relay capacity. In his installation a direct connection of the B2B to the battery is likely to be needed.

 

[Ronaldo]

Just completed a weekend away. Prior to starting the engine I removed the Van batt + fuse as suggested. Then started the engine and manually powered up the B2B charger using the +ve terminal on the leisure battery. I will get around to finding a switched live soon but any 12v source works. Everything appeared to work fine. Good charging volts to both batteries and the fridge worked on 12 volts as normal. When switching off the engine I replaced the Van batt fuse and disconnected the "D+" cable.
So all good. Thanks for your comments.

 

[autorouter]

Good charging volts to both batteries

The best test is to see if the voltages are different. If they are about the same, the split charge relay is still operating. If they are different, the B2B is operating independently of the alternator. It's possible that they are occasionally the same by coincidence, but if they are always the same the split charge relay is still working.