Victron B2B with original CBE setup ?

LeccyLee

LeccyLee

Joined
Jul 8, 2021
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54
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Location
Kent, UK
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82,523
MH
IH Oregon
Exp
1yr
Hi

I may have done a naughty and posted already on an old thread ( https://www.motorhomefun.co.uk/forum/threads/problem-charging-lithium.230956/post-4884657) but maybe I should ask this hear, apologises.

I have a 2005 IH Oregon with some difficulty keeping batteries charged, so I'm adding some Victron gear and then some new batteries. I have my Victron Orion to go in this week and have dilemma with the original CBE setup. Firstly as per other post, much of the internet says "Remove R37" on the CBE PCB, sadly mine must be too old as there is no R37. Problem 1.

However on Facebook ive also been advised to not worry about the original CBE setup, which I believe is just a simple split charge setup. Just to leave it doing its thing and connect the B2B up, and they will both run at same time without any issues? Correct, or bad no-no ?

I hoping to get this fitted Mon/Tue so if anyone can help, be grateful.
 
The opinion here is you need to disable the split charge relay.
Have you looked at the suggestions on the other thread?
More than one way to skin this cat. I was lucky to just cut the r37.
 
TheBaron said:
However on Facebook ive also been advised to not worry about the original CBE setup, which I believe is just a simple split charge setup. Just to leave it doing its thing and connect the B2B up, and they will both run at same time without any issues? Correct, or bad no-no ?
Click to expand...
I can see how someone might have that view. If a split charge relay has failed, so the leisure battery is not charging, someone might fit a B2B to 'boost' the charging. It would work fine, because the split charge relay is not working. In that rare event, you could then go on Facebook and tell the world you didn't need to disable the split charge relay.

I'd need to see test results using a clamp meter on the relevant wires to be convinced the split charge relay doesn't need to be disabled.
 
the1andonly said:
The opinion here is you need to disable the split charge relay.
Have you looked at the suggestions on the other thread?
More than one way to skin this cat. I was lucky to just cut the r37.
Click to expand...
Yes I think you are right, ive read through once, waiting to Saturday now hen have time to look better. Might even just de-solder the relay coil maybe?

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If you leave the split charge relay in the circuit and connect the B2B directly between the batteries the B2B and the SC relay will be effectively in parallel. Although it will work you lose the ability to charge the battery with the correct charging profile.
What you can do is connect the B2B in series with the split charge relay which makes the wiring easy but SC relay contacts often get a carbon build up on them as converters rarely fit any spark suppression to the contacts and you can end up with a reduced charge rate.
 
If you fit the b2b in line from the cbe when the relay closes it will charge through the b2b add a 70amp n/c across the b2b terminals with a d+ to open when running, that’s how mine works just fine and very simple 👍
I am getting 30amps in at the moment
 
A few people have mentioned fitting an extra relay such as Steve and Denise , I can't quite picture what it entails apologises, if anyone has the time id appreciate a diagram and photos maybe? I can't quite get my head around what you mean, blonde moments!
 
A B2B contains diodes that act as one-way valves so that amps can only flow in one direction, from the alternator/starter battery to the leisure battery. A split charge relay is a metallic contact, which allows amps to flow both ways.

When the engine is stopped and the alternator is not charging, the wire to the starter battery can be used for other purposes. To charge the starter battery from mains or solar for example, or to measure the starter battery voltage. This would be blocked if a B2B is connected in the wire somewhere.

To get around this, a relay is connected across the B2B terminals, but only when the engine is stopped and the B2B is not charging. That relay allows amps past the B2B, to charge the starter battery for example. As soon as the engine starts, the relay opens, cutting off that bypass route, allowing the B2B to do its job.
 
autorouter said:
A B2B contains diodes that act as one-way valves so that amps can only flow in one direction, from the alternator/starter battery to the leisure battery. A split charge relay is a metallic contact, which allows amps to flow both ways.

When the engine is stopped and the alternator is not charging, the wire to the starter battery can be used for other purposes. To charge the starter battery from mains or solar for example, or to measure the starter battery voltage. This would be blocked if a B2B is connected in the wire somewhere.

To get around this, a relay is connected across the B2B terminals, but only when the engine is stopped and the B2B is not charging. That relay allows amps past the B2B, to charge the starter battery for example. As soon as the engine starts, the relay opens, cutting off that bypass route, allowing the B2B to do its job.
Click to expand...
That’s what I was trying to say 👍 thank you

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I get the theory (I’m electrical engineer) but for some reason I couldn’t picture it.
No takers for photos or diagrams?
 
Just to further bolster Lenny HB comments on not isolating the SC relay, when the engine is running causing a parallel loop between B2B and SC relay, effectively putting a charge from both the alternator via the SC relay, plus the charge from the B2B, if not isolated properly, you may well experience as "Gadget John" has that he has now blown his EBL charger.
It doesn't even work on mains hook up! so he has bought another separate charger for hook up only as it should been wired in the first place, hopefully now with the correct charge profile selected.
He did state initially, that because he was using an "Isolated" Victron 30amp B2B there was "no conflict between the two" methods of getting charge into the leisure batts, he even bragged about how he was getting 20/30amps from the alternator when the engine was started from the alternator, then a few seconds later the B2B kicked in showing he was achieving 60/70amps into the leisure batts.
He is using Lithium's as well, which as we all know are charged in a completely different way to AGM's.
So Subscribers beware!
LES
 
TheBaron said:
I get the theory (I’m electrical engineer) but for some reason I couldn’t picture it.
No takers for photos or diagrams?
Click to expand...
This thread from 2019 has some pictures.
www.motorhomefun.co.uk

Carthago Split Charging Unit

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...
www.motorhomefun.co.uk www.motorhomefun.co.uk
 
Pausim said:
Gadget John will show you exactly how NOT to wire something.
Click to expand...
Yea I know, sadly many dont, my post was a nudge to see what response it would generate from LennyHB ;) Gadget John is obviously not worth his time time or effort, despite me using the word AGM in my text.:LOL:
Ah well, kettle on, need to use better bait next time.:giggle:
LES
 
TinaL said:
Yea I know, sadly many dont, my post was a nudge to see what response it would generate from LennyHB ;) Gadget John is obviously not worth his time time or effort, despite me using the word AGM in my text.:LOL:
Ah well, kettle on, need to use better bait next time.:giggle:
LES
Click to expand...
Seem enough of Gadget John's bodges to last a lifetime, one video was enough.:LOL:
 
When you say leaving it in situ would cause a conflict and parallel loop, I get that.. But, surely that's always the case with the solar charger being always on? Its always charging in parallel again with everything else?

As a sparky im fine with starting from scratch, I could happily wire the whole setup with chargers, relays etc, its just the CBE and existing motorhome wiring that throws me! Maybe I just rip it all out! ha

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TheBaron said:
When you say leaving it in situ would cause a conflict and parallel loop, I get that.. But, surely that's always the case with the solar charger being always on? Its always charging in parallel again with everything else?

As a sparky im fine with starting from scratch, I could happily wire the whole setup with chargers, relays etc, its just the CBE and existing motorhome wiring that throws me! Maybe I just rip it all out! ha
Click to expand...
No need just put a normally closed relay on the existing engine battery connection to the CBE, which will open using the D+ signal when the engine and B2B are running. See link at #16 for pictures.
 
I'll jump in here with an alternative idea, although I did mine 2 years ago so I'm going to have to check exactly what I've done mind.

I've also got an ih, a 2008 with the leisure battery mounted in the bottom of the cupboard behind the drivers seat, and found that the 50A fuse had overheated the fuse holder but not blown the fuse.
I ended up rewiring the charging circuit using a separate split charge relay and heavy cables and did away with the cbe split charge function completely by physically removing the starter battery input to the cbe ds320 as my van had a separate fridge relay mounted behind the fridge, and the automatic step was ignition controlled rather than engine controlled.
So there is now no starter battery input to the cbe panel, so no starter battery charge indicator but I can live with that
 
Pausim said:
No need just put a normally closed relay on the existing engine battery connection to the CBE, which will open using the D+ signal when the engine and B2B are running. See link at #16 for pictures.
Click to expand...
Ahhh.. I think finally the penny is dropping!
 
Bobby-gg said:
I'll jump in here with an alternative idea, although I did mine 2 years ago so I'm going to have to check exactly what I've done mind.

I've also got an ih, a 2008 with the leisure battery mounted in the bottom of the cupboard behind the drivers seat, and found that the 50A fuse had overheated the fuse holder but not melted.
I ended up rewiring the charging circuit using a separate split charge relay and heavy cables and did away with the cbe split charge function completely by physically removing the starter battery input to the cbe ds320 as my van had a separate fridge relay mounted behind the fridge, and the automatic step was ignition controlled rather than engine controlled.
So there is now no starter battery input to the cbe panel, so no starter battery charge indicator but I can live with that
Click to expand...
That is in fact something ive been considering! Im just trying to establish what will/won't work right if I do so.. Maybe some experiments this week with temp removing it.
 
TheBaron said:
That is in fact something ive been considering! Im just trying to establish what will/won't work right if I do so.. Maybe some experiments this week with temp removing it.
Click to expand...
I wanted to keep the engine battery connection to maintain the CBE functions, including the trickle charge when on hook up.

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Pausim said:
I wanted to keep the engine battery connection to maintain the CBE functions, including the trickle charge when on hook up.
Click to expand...
Yea, im not fussed about trickle charge of SB, as im full-time, my van gets driven daily 365days so SB unlikely to need any extra charging thankfully..
 
I think I just need to do some experiments, Pauls relay idea (now ive got it) seems feasible, but still a huge part of me, as an electrical engineer that still thinks "why". Im still struggling to see how both looped will affect anything much, maybe if you guys have lithium true. Im not, lithium in my view is a OTT complete unnecessary cost. Im still good ol Lead all the way!
 
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Possibly less of an issue with lead than lithium. However if the voltages are not matched the current can be flowing back through the loop rather than into the desired battery. The B2B should be monitoring the leisure battery to optimise charging but if the engine battery and alternator are also connected then it won’t be able to do this. In effect it could be powering itself which can’t be efficient. If the base vehicle has a smart alternator it is unlikely that you will get the leisure battery charged properly unless you cut the loop.
 
Pausim said:
Possibly less of an issue with lead than lithium. However if the voltages are not matched the current can be flowing back through the loop rather than into the desired battery. The B2B should be monitoring the leisure battery to optimise charging but if the engine battery and alternator are also connected then it won’t be able to do this. In effect it could be powering itself which can’t be efficient. If the base vehicle has a smart alternator it is unlikely that you will get the leisure battery charged properly unless you cut the loop.
Click to expand...
But as I said, the solar setup is already doing just that, creating a loop. So even with your relay the solar loop still creates a parallel.
 
TheBaron said:
But as I said, the solar setup is already doing just that, creating a loop. So even with your relay the solar loop still creates a parallel.
Click to expand...
That is a parallel feed not a loop and the one with the lowest voltage will just stop flowing. A loop is different because it is going round in a circle back to the same source. Your B2B is not only trying to charge the leisure battery but is feeding back through the original relay to the engine battery which in turn is powering the B2B. This means the B2B can’t monitor the leisure battery and the vehicle‘s systems can’t monitor the engine battery.

Does your base vehicle have a smart alternator?

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