B2B Trickle Charger

[ShaKen]

I’ve installed Solar in my van - Victron MPPT Smart Controller as well as a Victron Smartshunt to monitor Hab battery health as well as Cab vbattery voltage. I’m now thinking I need to stick in a B2B trickle charger to keep the Starter battery topped up if off grid.

I see there are some coming in from £150 upwards but also noticed the Votronic B2B Standby (trickle) charger which provides 3A max to the Starter battery from the hab batteries.

At £45 it looks inexpensive and probably just what I need. https://www.votronic.de/index.php/en/products/peripheral-units/cut-off-relays

Have I missed something / misunderstood what I need.

 

[Googlebot]

Battery master? Same thing but probably cheaper.

 

[DBK]

It sounds like a Battery Master which is what we have. The term B2B is usually used for something very different which takes its power from the running engine. The device you have linked to is for when the engine is not running with power coming from EHU or solar.

 

[quickweh]

I've fitted a CBE split charge relay. Works a treat on solar in summer and hook up at home on the drive. Vehicle 2009 Fiat heavy chassis 3.0l engine.
12 Volt planet good source of technical advice.

CSB2 - CBE

Electronics for Caravanning and Boating

www.cbe.it

CBE CSB-2 battery charge relay operation.

Hi, I've installed a CSB-2......I think I have done it correctly, but am not getting a lit LED. Does this just come on when charging of the starter battery is activated or should it be lit all the time once the device is installed correctly? ? Thanks for any help.

www.motorhomefun.co.uk

Voltage Sensitive Split Charge Relays | 12 Volt Planet

Voltage sensitive split charge relays for isolating and charging auxiliary and lesiure batteries in low voltage automotive & marine applications.

www.12voltplanet.co.uk

 

[peterc10]

I think you have us a bit confused. The term B2B refers to a charger that can be used to charge the leisure (not starter) batteries at a very high rate from the alternator when the engine is running. It is certainly not a trickle charge. You may need something that will trickle charge from the leisure battery to the starter battery. I say "may" because many motorhomes have that built in already. If yours does not have that built in then many on here recommend the Battery Master.

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[ShaKen]

Thanks all.

Yes, I may we’ll have been using B2B term incorrectly (although of course it will be charging the Cab battery from the Hab battery).

I must admit I am still a bit confused as to whether my install does trickle charge from the cab 12v system or not. Certainly the 12V CBE DS30 consumer / fuse box does not have a connection to the B1 stud thus not connected to the starter battery. And my CBE516 charger appears to only have one output to the Cab battery.

I wonder if I could do a continuity test from the +ve on both cab & starter batteries to determine if they are connected; which begs another question, would a continuity test (via my multimeter) work through a trickle charger in the circuit)?

 

[peterc10]

I must admit I am still a bit confused as to whether my install does trickle charge from the cab 12v system or not. Certainly the 12V CBE DS30 consumer / fuse box does not have a connection to the B1 stud thus not connected to the starter battery. And my CBE516 charger appears to only have one output to the Cab battery.

I wonder if I could do a continuity test from the +ve on both cab & starter batteries to determine if they are connected; which begs another question, would a continuity test (via my multimeter) work through a trickle charger in the circuit)?

Tell us exactly what make model and year of motorhome you have and somebody with the same set up may be able to tell you.

If you have not got one fitted the battery master is a very simple little device that allows the habitation battery to trickle charge the cab battery once the difference between their charge levels drops below a certain level.

 

[ShaKen]

It’s a 2018 model Chausson 640 Welcome VIP.

 

[DBK]

Thanks all.

Yes, I may we’ll have been using B2B term incorrectly (although of course it will be charging the Cab battery from the Hab battery).

I must admit I am still a bit confused as to whether my install does trickle charge from the cab 12v system or not. Certainly the 12V CBE DS30 consumer / fuse box does not have a connection to the B1 stud thus not connected to the starter battery. And my CBE516 charger appears to only have one output to the Cab battery.

I wonder if I could do a continuity test from the +ve on both cab & starter batteries to determine if they are connected; which begs another question, would a continuity test (via my multimeter) work through a trickle charger in the circuit)?

Its easy to check if you have a voltmeter.

Disconnect the MH from any EHU in say the afternoon and when it gets dark (assuming you have solar) check the voltage of the cab battery. It should be something around 12.5 to 12.7 volts. Then plug in the EHU or if not on EHU wait until the sun comes out (!) and check the cab battery again. You should see something around 13.5 to 13.7 volts. If you see the same 12.5 volts or whatever it was you don't have a trickle charge device - or if you do it isn't working.

 

[Sasbo]

ShaKen have a look at page19, 28 and 29 of the Chausson manual.

Page 19 advises there is a coupling relay installed between the two batteries that allows hab and vehicle batteries to be simultaneously charged when the engine is running. This relay also separates the batteries when on hookup so it seems to suggest that the CBE 516 charger does not charge the vehicle battery on hookup.

Page 28 suggests that the CBE control panel does not support vehicle battery charging when on hookup. 'B1 engine battery charging: function not available'.

Hope this helps.

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[ShaKen]

ShaKen have a look at page19, 28 and 29 of the Chausson manual.

Page 19 advises there is a coupling relay installed between the two batteries that allows hab and vehicle batteries to be simultaneously charged when the engine is running. This relay also separates the batteries when on hookup so it seems to suggest that the CBE 516 charger does not charge the vehicle battery on hookup.

Page 28 suggests that the CBE control panel does not support vehicle battery charging when on hookup. 'B1 engine battery charging: function not available'.

Hope this helps.

Thanks Sasbo - that’s what I thought.

 

[Nasher]

I use a Vanbitz Battery Master, available from Motorhome Fun at a discount, to keep my cab battery topped up

Battery Master

Simple to fit, but for those who prefer not to do electrics, a simple job for an auto electrician

 

[XxAnthxX]

Next you will need to decide what type of charging system you want.

The Battery Master and CBE CSB2 type systems work in different ways, both have their pro’s and con’s.

The Battery Master will connect both batteries when there is a voltage difference between the two batteries and disconnect when there isn't. This will maximise the duration which cab battery will remain charged (in storage etc), but eventually flatten both batteries if there is no hook up or solar input.

The CSB2 types will connect and disconnect the batteries only when the hab battery reaches set voltage thresholds. This will only maintain your cab battery when your hab battery is receiving charge from an external source such as hook up or sufficient solar.

so it depends on what you want or need.

 

[ShaKen]

All sorted! Votronic Standby (trickle) charger installed.

Thanks all for the comments / advice.

 

[dewierwan]

Hi everyone, I have a B2B for charging the leisure battery from the alternator, but also want a trickle charger to charge the starter battery from the solar panels. How do I wire these up? Do I wire the B2B and the trickle charger in parallel? Thanks!

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[autorouter]

Basically, yes. The B2B requires substantial wiring because it is carrying quite a high current - 20 to 30A is typical. The trickle charger will only be supplying a small current, typically 1A, so can use thin wires, and/or use the B2B wires if that is convenient. If you are connecting a thin wire to a thick wire, a small inline fuse is a good idea, maybe 2A or 5A.

 

[Vipar]