Cab Battery Wiring

[Silver-Fox]

Good afternoon fellow Funsters.

I’m looking for a pointer from one of you clever lot how to wire in and charge my cab battery from the MPPT controller.

Prefer not to run a cable from the back of the van where all the electrics are.

I have been reliably informed I can do the above using a connection via my CBE unit.

I have a Rapido 995M van.

Pictures of my set up below.

Thanks

 

[Silver-Fox]

I’ve had a look through my owners manuals but unfortunately can’t find a wiring diagram

 

[Two on Tour]

Where is your hab battery located Richard ?

 

[Silver-Fox]

Hab battery and all solar/wiring is in the garage at the rear.

If I need to I can run a cable to the front but would prefer not to.

 

[Two on Tour]

Hab battery and all solar/wiring is in the garage at the rear.

If I need to I can run a cable to the front but would prefer not to.

Can't help you unfortunately with your CBE setup as I know bugger about that system, but as ever your easy option might be a Battery Master, one small single wire to your cab battery run under your van.

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[GeoffnDee]

The large terminal on the far lower left in the photo if marked +B1 could be the Starter (Cab) battery connection positive side and there may be another marked -B1 for the negative side (I cannot see them in the photo but if they are there you can confirm things with a meter , the+B2 terminal shown on the far right may well be the positive supply from the leisure battery) )

 

[Silver-Fox]

Can't help you unfortunately with your CBE setup as I know bugger about that system, but as ever your easy option might be a Battery Master, one small single wire to your cab battery run under your van.

I can run a cable from my MPPT controller as I have a spare out I can use apparently.

 

[Two on Tour]

I can run a cable from my MPPT controller as I have a spare out I can use apparently.

That's only good for topping up your cab battery as long as the sun shines, whereas a Battery Master keeps your cab battery topper up all the time. (well pretty well all the time - to keep the pedantic's happy )

 

[Silver-Fox]

The large terminal on the far lower left in the photo if marked +B1 could be the Starter (Cab) battery connection positive side and there may be another marked -B1 for the negative side (I cannot see them in the photo but if they are there you can confirm things with a meter , the+B2 terminal shown on the far right may well be the positive supply from the leisure battery) )

Pictures below

It looks like

 

[Silver-Fox]

Another picture

To confirm +B terminals to the right and negative to the left.

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[Silver-Fox]

And the MPPT controller

 

[Silver-Fox]

That's only good for topping up your cab battery as long as the sun shines, whereas a Battery Master keeps your cab battery topper up all the time. (well pretty well all the time - to keep the pedantic's happy )

Hi Paul

Yes as you say only when the sun shines.

I have very little drain on the cab battery when the van is laid up.
And as we know the sun always shines in Gloucestershire

 

[Silver-Fox]

I love this forum, great response for a “techie” question

 

[Sheddy]

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This will do what you require, it will top up the cab battery with a small charge when the leisure batteries are at 12.5v or above. It is relatively easy to wire in, only 3 connections required. I have fitted mine connected direct from leisure batteries to cab battery as they are both at the front of our van.

 

[Silver-Fox]

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This will do what you require, it will top up the cab battery with a small charge when the leisure batteries are at 12.5v or above. It is relatively easy to wire in, only 3 connections required. I have fitted mine connected direct from leisure batteries to cab battery as they are both at the front of our van.

This is what I’m trying to avoid, running a cable the length of the van.
Cab battery is at the front and hab at the back in the garage.

I’d also be using solar with that set up.

Thanks for the suggestion though

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[GeoffnDee]

You need to check with a meter but I think you should find that the +B1 is starter battery positive connection and +B2 is the leisure battery positive connection and also you may find that the -B terminal is a negative connection for both , If this checks out these connections could also be used for wiring in a battery master if you decided to fit one.
I cannot see the solar control connections but , if it is a duel controller , you could connect the second output to the points +B1 and -B to send a solar charge to the starter battery.

 

[Silver-Fox]

You need to check with a meter but I think you should find that the +B1 is starter battery positive connection and +B2 is the leisure battery positive connection and also you may find that the -B terminal is a negative connection for both , If this checks out these connections could also be used for wiring in a battery master if you decided to fit one.
I cannot see the solar control connections but , if it is a duel controller , you could connect the second output to the points +B1 and -B to send a solar charge to the starter battery.

Thanks for your help.

I can check in my user manual which +B is the cab battery.

I’ve been told the battery + output from the solar controller can be used to trickle charge to the cab battery.
It’s the first of the smaller outputs on the controller.

 

[Silver-Fox]

Just had a thought if I connect to the correct place to trickle charge the cab battery.

Could I damage the MPPT controller when on EHU?

 

[GeoffnDee]

No it will not damage the MPPT, connecting in this way is an often used method of connecting duel solar controllers (and battery master units) into the battery systems.

 

[Silver-Fox]

No it will not damage the MPPT, connecting in this way is an often used method of connecting duel solar controllers (and battery master units) into the battery charging systems.

Many thanks for your posts.

I’ll check which point on the cbe is for the cab battery and get it wired up

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[autorouter]

There's probably no need to run a negative for the starter battery trickle charge, the two battery negatives will be connected to the chassis. The trickle charge amps is very small, so no problem with voltage drop. Note 'MASSE' next to the negative bolt on the circuit board means chassis.

 

[Silver-Fox]

There's probably no need to run a negative for the starter battery trickle charge, the two battery negatives will be connected to the chassis. The trickle charge amps is very small, so no problem with voltage drop. Note 'MASSE' next to the negative bolt on the circuit board means chassis.

Thankyou for the above.

It sometimes looks a bit daunting when you delve into these boxes.

I’ve never liked 12v electrics.

Happy to get inside a consumer unit though

 

[autorouter]

It sometimes looks a bit daunting when you delve into these boxes.

I’ve never liked 12v electrics.

While you are looking at it, the small black box with '70A 12V' on it, between the B1 and B2 terminal bolts, is the famous split charge relay, that connects B1 and B2 together when the engine is running.

 

[Silver-Fox]

While you are looking at it, the small black box with '70A 12V' on it, between the B1 and B2 terminal bolts, is the famous split charge relay, that connects B1 and B2 together when the engine is running.

Ok thanks

Do i need to do anything other than connect a cable from the MPPT controller "starter" out put connection?
Just checking

 

[autorouter]

Do i need to do anything other than connect a cable from the MPPT controller "starter" out put connection?

Yes, I think that's all you need to do. Doesn't have to be thick wire either, it's only about an amp, so very little voltage drop even for ordinary 1.5mm2 wire.