Carthago Split Charging Unit (1 Viewer)

[Pausim]

Interested to know how you've connected the fairly heavy cable that comes from the starter battery, to your new relay, and the relay to the B1 terminal. The relays seem only to have spade terminals. Are they adequate for the job?

Working out how to attach the short length of heavy cable available to the relay was a challenge. In the end I used a fuse carrier with studs and nuts and simply attached the cable with it‘s existing ring terminal onto it. I then wired the other end to the relay using 10mm cable and a heavy duty bulkhead socket. Then from this back to B1 on the CBE board, again using a short length of 10mm cable. I decided this socket https://www.arc-components.com/0-729-04-durite-heavy-duty-bulkhead-socket-for-relays.html would make more more secure connections in the confined space. The fuse carrier sits snugly alongside the CBE unit and is there for the ease of connection not because a fuse is needed at this point.

 

[Pausim]

For the few occasions that I hook up to mains, I may just keep it simple and isolate that cable from the CBE with a manual isolator switch.

You might also lose the engine battery reading from the control panel. An alternative location for the relay might be in the engine battery compartment where the other end of the cable connects.

 

[Mr David]

I have followed this thread, with interest, and I see great merits to the solution that Pausim has adopted. There is, in my opinion, a need to isolated the engine and leisure batteries after fitting a B2B charger as that is one of the reasons for fitting it as the two battery systems require different charging regimes.
With Pausim solution I would expect the loss of an engine battery voltage reading from the MH control panel, but I don't see that as a problem because the reading should return once the engine is no longer running. My main concern, though, is that there would also be the loss of the 12 volt supply to power the fridge when the engine is running.
Has Pausim been able to confirm if his fridge still works on 12 volts when the engine is running?

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[Pausim]

I have followed this thread, with interest, and I see great merits to the solution that Pausim has adopted. There is, in my opinion, a need to isolated the engine and leisure batteries after fitting a B2B charger as that is one of the reasons for fitting it as the two battery systems require different charging regimes.
With Pausim solution I would expect the loss of an engine battery voltage reading from the MH control panel, but I don't see that as a problem because the reading should return once the engine is no longer running. My main concern, though, is that there would also be the loss of the 12 volt supply to power the fridge when the engine is running.
Has Pausim been able to confirm if his fridge still works on 12 volts when the engine is running?

I hope to be able to check the 12V fridge operation tomorrow. I think it will be ok because it looks as if the supply comes from the live side of the CBE unit with its own D+ operated relay. In normal operation both batteries are connected to this live feed when the engine is running. In my set up it will only be the leisure battery connected but this will be getting a healthy supply from the B2B.

 

[Pausim]

Fridge still switches over to 12v operation automatically when the engine is running. No problems identified yet.

TinaL photo as requested.



Relay bottom left.

 

[G7UXG]

Pausim Any idea what the small grey box is, at the bottom right with a clip-on lid? Mine has two small fuses in it, but I don’t know what they’re for.

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[Pausim]

Pausim Any idea what the small grey box is, at the bottom right with a clip-on lid? Mine has two small fuses in it, but I don’t know what they’re for.

Sorry no idea what the fuses are for. I haven’t got my manual at home but it probably will not help.

 

[G7UXG]

The manual doesn’t help at all.

 

[Pausim]

Not surprised.

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[Wagoneer]

Pausim, you will be pleased to know that Clive Mott, MMM electrical guru, respond to a query about installing a B2B in the the MMM January 2020 issue, page 132.

He describes the use of a NC relay, exactly as per your circuit diagram.....not that I was ever doubting your solution

However, he failed to add that it was only applicable to systems where the 12v power to the fridge was supplied from the leisure battery.

I've identified the simulated D+ wiring in my CBE box, built around 2009. Conveniently, it is coloured yellow and marked with D+.

I might add that I never had any charging issues with my previous Hymer (Schault) but the Carthago (CBE) has been very poor in this regard. Possibly, the onboard 30amp split-charge relay is passed it's best.

 

[nabsim]

I have been looking at disabling the battery parallel option on the CB300 also. There is a two pin connector inside the DS300 marked as number 18 on the drawings. Pin 1 is ignition sense (D+) and pin 2 is CBE battery charger sense.

I am thinking of just removing the pin 1 from the plug going to socket 18. From what I can see this will disable the onboard relay so starter and habitation battery’s can’t link together.

I can’t see from any of the diagrams that it will affect anything else. Has anyone tried this?

 

[Pausim]

I have been looking at disabling the battery parallel option on the CB300 also. There is a two pin connector inside the DS300 marked as number 18 on the drawings. Pin 1 is ignition sense (D+) and pin 2 is CBE battery charger sense.

I am thinking of just removing the pin 1 from the plug going to socket 18. From what I can see this will disable the onboard relay so starter and habitation battery’s can’t link together.

I can’t see from any of the diagrams that it will affect anything else. Has anyone tried this?

I think it will also affect the 12V operation of the fridge.

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[nabsim]

I think it will also affect the 12V operation of the fridge.

I think I may give it a go as a first option and see what happens. Not sure if the fridge would matter but would have to check/ask.

edit: actually, looking at it again what would you expect to happens if fuse 10 was pulled here?

 

[Pausim]

Not sure about the fuse. Also not sure whether the step alarm is somewhere on this circuit or picked up from the D+ at the engine end.

 

[nabsim]

What I am looking at isn’t on a Cathargo but it’s similar equipment in parts which is why I posted, for my situation rather than others so sorry for hijack. I think I need to try a few things with multimeter to hand ?

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[Pausim]

What I am looking at isn’t on a Cathargo but it’s similar equipment in parts which is why I posted, for my situation rather than others so sorry for hijack. I think I need to try a few things with multimeter to hand ?

The DS300 is likely to behave the same.

 

[andy63]

ill resurrect this thread just to thank the contributors Pausim G7UXG and others.. I did contribute and at the time but couldn't see the need for the measures and lengths you were going to to install a B to B charger..
well lets just say that faced with the same task myself and that having the effect of concentrating my mind a bit I now get it..
thanks again
Andy

 

[G7UXG]

Still haven't progressed things as yet.

I'm thinking of adding another 80ah Exide gel battery to the two I've already got. The motorhome was built in August 2018 and registered in June 2019, so they're 18 months old with 8 months' use, so hopefully may be OK to add another one to them. The other option is to push the boat out and buy two 100ah lithiums, but I'm not sure that's good value at the moment.. weight isn't an issue.

Then, I will add a B2B charger, advice appreciated as to whether to go for a Sterling or a Votronic. Probably will need a larger mains charger as well, or perhaps not? (it's a 16A charger at the moment).

May also consider moving the batteries towards the front of the motorhome. It's a 5 tonne tag axle and the batteries are behind the rear axles. No big deal weight wise, as there's about 200kgs spare on the rear pair of axles, but it would shift a bit of weight forwards.

The benefit would be shorter cables between the starter battery and the B2B, and short cables from the B2B to the leisure batteries. Downside is a longer cable to the distribution panel.

Need to start collecting the bits and pieces ready to do the job in the spring when the weather's a bit more pleasant.

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[PJGWiltshire]

I'm exploring the possibility of putting a B2B charger on my Carthago, but I understand that I'll need to disable the existing split charging unit. Does anybody know where it is? Is it a separate unit, or is it built into the electronic gubbins in the boot? I can't even identify a fuse for it. Is it likely to be an ordinary automotive fuse, or one of the midi fuses which are attached to the multi-connector that is on the +ve of the vehicle battery?

It's a Carthago 5.5XL but I think the electrics are the same on all the 'A' classes. Electronics are CBE

Might even consider a Votronic triple unit (mains/B2B/solar), although they're a bit expensive.

Thanks in advance.

Hope you can help

Saw your original post from last year.

I am also intending to put a Stirling B2B charger on a Carthago Chic C line. By chance did you self install one on your van. If so was it simples.

 

[Poutie57]

I have a Laika kreos 5009 which has a cbe set up similar to the Carthago And didn’t touch the cbe side at all just installed the B2B as Sterling recommended and alls been well over the last year and we wild camp 60% of the time (10,000 miles). I read and re-read all the posts on B2b installations regarding fitting relays etc but felt this was the best way to go basically running the B2b as a separate system

 

[Pausim]

I have a Laika kreos 5009 which has a cbe set up similar to the Carthago And didn’t touch the cbe side at all just installed the B2B as Sterling recommended and alls been well over the last year and we wild camp 60% of the time (10,000 miles). I read and re-read all the posts on B2b installations regarding fitting relays etc but felt this was the best way to go basically running the B2b as a separate system

Running the B2B as a separate system makes sense, however to do this I found I needed to add a relay as described earlier. The Sterling manual shows a basic wiring arrangement which is fine but most motorhomes already have a split charging or battery linking relay which complicates matters by joining the two systems and removing the separation.

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[G7UXG]

PJGWiltshire funny you should resurrect this thread. I've just fitted one this weekend. I went for a Votronic VBCS triple unit (45/30/350), the middle one of their range that provides 45amps B2B, 30amp mains charger and will take 350wh of solar panels. Battery cables from the starter battery, mains power and solar all feed into the VBCS and it sorts the rest out.

The downside is that if it goes wrong, the whole lot may pack up, but I've allowed for that and prepared accordingly.

The split charge relay is built into the CBE unit and when the engine is started and D+ has sufficient voltage, the split charge simply parallels the starter and leisure batteries by linking terminals B1 (starter) and B2 (leisure together). The lead that connects to B1 at the CBE is blue, but there aren't any blue leads at the starter battery and so I set about tracing the wire. It goes to the front of the van along the offside and terminates behind a small panel that is alongside/behind the handbrake (I'm referring to a right hand drive model here). Take off the panel (three screws) and there are a whole lot of wires there. the blue wire connects to a chunky black plug with a red and black lead at the other side. This goes to the starter battery. To disable the split charge, simply unplug this connector. The CBE split charge relay still works but the the leisure battery voltage is now on both terminals rather than the starter voltage (this comes in useful later on).

I know that Pausim has done things differently but he needed to maintain the original mains charging facility. My new VBCS includes a new mains charger and so I just unplugged the mains connector of the original CBE 16amp charger and left it in situ and out of use.

I could also have just taken the cable off B1 at the CBE to disable the split charge but that would need securing somewhere, and I'd traced the wire to the connector anyway.

So, I've disconnected/disabled the original mains charger and split charge system, and I've completely disconnected the solar panel from the original regulator and will wire it directly the Votronic unit (that's Friday's job... need some terminals to sort that out).

The Votronic unit needs a D+ signal to switch it on as it's not voltage sensing. I prefer that option to the voltage sensing method. There is a D+ signal wire above the fridge in my van. It's part of the satellite wiring system and is used to put the sat dish down when the engine is started. I could quite easily run a wire from there to the back of the van (that's where all of the electronics are) and use that to switch the Votronic charger on to B2B mode.

However, I realised that when the engine is not running, because the split charge cable is disconnected, the B1 terminal of the CBE is at zero volts. When the engine is running, the split charge relay in the CBE kicks in and the B1 terminal is now at the same voltage as the leisure batteries, i.e 12 volts or so (depending on their state of charge). So I have connected the Votronic charger's D+ terminal to B1 of the CBE as the only time it has voltage is when the engine is running. It's not affected by the original mains charger because that is disconnected. If it wasn't, my plan wouldn't work because the original mains charger also charges the starter battery through that terminal. I haven't yet found a downside to this method. I suppose it would fall over if the leisure batteries went to less than 10 volts or so, in which case I've got a problem anyway.

The CBE panel above the door obviously doesn't report the starter battery voltage any more because it's disconnected. By the way, the Votronic unit also charges the starter battery on mains and solar.

If the Votronic all goes wrong, then it's a simple case of disconnecting the D+ wire, reconnecting the split charge cable and plugging in the original mains charger, it'll take 10 minutes. The only thing I would lose is solar power. I may, at a later date, fit a cross-over switch so that I can just switch the B1 terminal between a connection to the Votronic unit's D+ terminal or to the original split charge system. If I have any problems with my solution to the D+ signal, I'll just wire it direct from above the fridge, but so far, it seems to work well. l've used 25mm sq cable throughout, put an extra battery on to give me 240ah, and replaced all of the battery leads with 25mm sq cable.

I've also bought a NASA battery monitor which I've yet to fit so that I can keep an eye on things. That will be fitted in the cab on the passenger's side, in the panel where a reversing camera would go if it was a left-hand-drive. The information on the CBE control panel above the door is largely redundant and it's now just a switch panel.

Hopefully, it'll all work OK and secure my power needs. Might add a second solar panel later in the year.

It wasn't technically difficult, just a bit of a fiddle to get the cables through. I bought a proper cable crimping tool to make sure all of my connections were good. It all took me a couple of days but I know where everything is and how it all works. If I'd have paid someone to fit it, I would be in the dark.

All in all, it's easily achievable by a competent DIYer.

Mike

 

[PJGWiltshire]

Thanks for the info. Lets me go through your reply again and if you do not mind can i drop you a line if i get stuck

 

[Pausim]

I know that @Pausim has done things differently but he needed to maintain the original mains charging facility. My new VBCS includes a new mains charger and so I just unplugged the mains connector of the original CBE 16amp charger and left it in situ and out of use.

I like your solution, makes good sense with your VBCS. Well done for finding where the blue B1 battery wire turns red, that had puzzled and defeated me. I now know where to look, indeed it might have been a better point to insert my relay into the circuit but I am not planning on changing it now that it is set up and working.

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[G7UXG]

Pausim I think I remember that yours is a Votronic B2B. If so, I assume it needs a D+ signal to switch it on? Where did you pick that up from to switch your relay?

 

[Pausim]

Pausim I think I remember that yours is a Votronic B2B. If so, I assume it needs a D+ signal to switch it on? Where did you pick that up from to switch your relay?

I had some of the new wiring put in by the dealer before I purchased. This included a new 50A engine battery connection in the leisure battery compartment with a D+ powered relay. I am not sure where they picked up the D+, the motorhome is in storage and unfortunately I am not currently in a position to pop out and check. My additional isolating relay is triggered from the relay installed for me.

Edit. Sorry, yes it is a Votronic VCC1212-45 and the D+ trigger is picked up from the dealer installed relay.

 

[Steve and Denise]

JockandRita

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[JockandRita]

JockandRita

Thanks for the "heads up" to this thread Steve.

Cheers,

Jock.

 

[the1andonly]

Perhaps the most straightforward solution might be to disconnect the starter battery cable from B1 of the CBE. It sounds like this wire goes directly to the starter battery, through a fuse which is mounted at the starter battery end. Could this then be connected to the relevant terminal of the B2B?

Pausim
For the few occasions that I hook up to mains, I may just keep it simple and isolate that cable from the CBE with a manual isolator switch.

The use of a manual issolator and wiring up a b2b to the removed B2 and the B1 on my cbe300 sounds like a simple doable solution. Pausim the d+ is even close to hand 12 on cbe. The fridge runs off hab battery.
This is on a rapido using a votronics 1212-30
The location next to cbe rather than near batteries has merits due to need to relocate solar controlers (votronics duo) to battery box due to length of temperature sensors. Or can sensors be extended more than 3m? Adding lithium, hence need for temp sensors.

 

[Pausim]

Not sure about extending temperature sender, probably best to check with manufacturer. My B2B is next to the Li battery so I have not experienced this problem. Extending the D+ feed may be easier.

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