B2B charger install query

[RichardB]

Hi all
I am considering getting either a Sterling or Victron B2B charger to boost the charge time on my leisure batteries.
My motorhome is a 2013 Elddis 115. I think I will need to disconnect the connection that currently charges the leisure battery so it doesn’t create a loop but I still need to power the fridge when van is moving.
Has anyone fitted a B2B to an elddis, did you disconnect the existing charge cable and if so how and where so the fridge still works
Thanks

 

[autorouter]

The method for disabling the existing charging connection (split charge relay) without disabling the other functions varies depending on the exact make/model of the distribution/fusebox. What make/model is it?

 

[RichardB]

The method for disabling the existing charging connection (split charge relay) without disabling the other functions varies depending on the exact make/model of the distribution/fusebox. What make/model is it?

It’s a BCA similar to this piccy

 

[Two on Tour]

Are you sure that your leisure battery is being charged via the alternator as we have the same BCA gear on our 2013 Elddis Autoquest 175 and found our leisure battery was being charged via the alternator
which is backed up by what it says in the Elddis owners handbook.

I fitted a Sterling BB1260 and wired it directly to our leisure battery via our Victron shunt and because I'm bypassing the BCA unit the fridge works fine.

 

[RichardB]

Yes I’m sure it does. There is one cable comes out of the BCA to the leisure batteries - when ignition is running it has 13v on it

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[Two on Tour]

Yes I’m sure it does. There is one cable comes out of the BCA to the leisure batteries - when ignition is running it has 13v on it

That could well be the voltage from the relay triggered by the D+ to fire the fridge relay to run it on 12volts.
To see for definite, check the voltage on your leisure battery and then with the engine running.

 

[RichardB]

The voltage on that cable goes to 13v when engine is running

 

[Two on Tour]

.

 

[Two on Tour]

Apologise, I think I need to correct myself here as I believe I'm getting mixed up with it being that the 240v charger only charges the leisure battery and not the starter battery as well, as this was a discussion sometime back on another thread, which was why I fitted a Battery Master.

Bypassing the BCA unit and going direct to your leisure battery is probably the easy option.

 

[autorouter]

Bypassing the BCA unit and going direct to your leisure battery is probably the easy option.

That's Part 1 of what has to be done. Part 2 is, as the OP says, to disable the connection between the starter and leisure battery

I haven't got a picture of a BCA circuit board. I can tell you what needs to be done, but not how to do it. Looking at the circuit board, there will be a power input wire from the starter battery and leisure battery. Close to where they connect to the PCB, there will be a relay (a small black plastic box). There will be several relays, but the split charge relay is likely to be the one closest to the two power input pins

Once you have identified the relay, it's a matter of disabling it. The relay will have two power pins and two trigger pins. Obviously removing the relay by desoldering it will definitely work. Alternatively the trigger signal sometimes comes in through a resistor or a wire link, which is easy to cut. Looking at the tracks on the back of the PCB you can trace the path of the trigger signal from the relay pin.

You have to be careful, because you can't just cut the complete trigger signal (labelled D+ on most PCBs) where it comes into the PCB, because it's used to trigger the other relays that you don't want to disable.

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[Two on Tour]

That's Part 1 of what has to be done. Part 2 is, as the OP says, to disable the connection between the starter and leisure battery

I haven't got a picture of a BCA circuit board. I can tell you what needs to be done, but not how to do it. Looking at the circuit board, there will be a power input wire from the starter battery and leisure battery. Close to where they connect to the PCB, there will be a relay (a small black plastic box). There will be several relays, but the split charge relay is likely to be the one closest to the two power input pins

Once you have identified the relay, it's a matter of disabling it. The relay will have two power pins and two trigger pins. Obviously removing the relay by desoldering it will definitely work. Alternatively the trigger signal sometimes comes in through a resistor or a wire link, which is easy to cut. Looking at the tracks on the back of the PCB you can trace the path of the trigger signal from the relay pin.

You have to be careful, because you can't just cut the complete trigger signal (labelled D+ on most PCBs) where it comes into the PCB, because it's used to trigger the other relays that you don't want to disable.

BCA PDU schematic

 

[Two on Tour]

Our van and a couple of other Elddis Autoquest that I have had dealings with, have a CBE SRX 250 relay unit which has a D+ feed to it at the bottom of the drivers side "B" post.

 

[Hoovie]

.... You have to be careful, because you can't just cut the complete trigger signal (labelled D+ on most PCBs) where it comes into the PCB, because it's used to trigger the other relays that you don't want to disable.

You are quite correct there. It activates the Split-Charge, Provides 12V to the 3-way fridge, disables the Hab electrics (EMC "rules") and retracts the Step (if fitted).

I did actually fit a Victron B2B to a Bailey with the same BCA unit, and I took the easy option of just pulling the fuse to disable the D+ signal getting passed to the BCA
Allowed the B2B to work well. There was no Step on this van, Bailey never connected the Fridge to the 12V to start with (design? fault? don't know) and having the Hab Electrics carry on working was a bonus for the owner! win-win.

 

[Two on Tour]

Our van and a couple of other Elddis Autoquest that I have had dealings with, have a CBE SRX 250 relay unit which has a D+ feed to it at the bottom of the drivers side "B" post.

This relay unit is used to switch off the hab electrics and switch a 12v feed to the fridge when it gets a D+ signal from the alternator.