Whilst driving, does the 3 way fridge source it’s power from the vehicle or the habitation battery ?

[No-Dun-Roamin’]

I thought I knew the answer to this, which is that the fridge connects to the starter battery/ alternator while driving.

But now I’m not so sure. I now have a lithium battery and a Sterling Power B2B charger. When this was installed, I think, to disconnect the split charge relay, one of the connections to the CBE thingy was disconnected. I have an app to monitor the Lithium battery charge/ discharge rates. While driving, there is a 9 Amp draw from the leisure battery, which presumably, must be going to the fridge.

Confused, but looking for enlightened guidance . . .

 

[Charlie9038]

Sounds about right, as I understood when driving it will maintain the current temp, which will draw from the 12v battery

 

[Captain Yoghurtpot]

I am no Auto or electrical guru, and there are some very knowledgeable people on here, but my van is 20 years old, runs lead acid leisure battery and to get 12v to the fridge it can only be done with the engine running and I believe that is direct from the alternator, with not a lot going into the cab battery or any into the leisure battery.
Switch off the fridge on 12v whilst travelling and the cab battery gets a good schooling with, I believe, some going to the leisure battery, but only whilst the fridge is not engaged.
But please don’t take my word as gospel.

 

[cmcardle75]

I thought I knew the answer to this, which is that the fridge connects to the starter battery/ alternator while driving.

But now I’m not so sure. I now have a lithium battery and a Sterling Power B2B charger. When this was installed, I think, to disconnect the split charge relay, one of the connections to the CBE thingy was disconnected. I have an app to monitor the Lithium battery charge/ discharge rates. While driving, there is a 9 Amp draw from the leisure battery, which presumably, must be going to the fridge.

Confused, but looking for enlightened guidance . . .

Sounds like something is going very wrong if your leisure battery is actually draining 9A whilst driving.

 

[Podney]

Why would the power have to come from the leisure battery when the engine is running? I thought it came from the alternator.......why wouldn’t it????

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[No-Dun-Roamin’]

It only has the draw, when the fridge is on ! I usually have the B2B on standby when the leisure battery is fully charged from the solar panel Before a journey. However I now put it on when the fridge is on and this more than compensates for the 9 Amp draw, otherwise the leisure battery would have lost a percentage of its charge, after a reasonable journey.

 

[DBK]

It only has the draw, when the fridge is on ! I usually have the B2B on standby when the leisure battery is fully charged from the solar panel Before a journey. However I now put it on when the fridge is on and this more than compensates for the 9 Amp draw, otherwise the leisure battery would have lost a percentage of its charge, after a reasonable journey.

You've completely confused me - but that is easily done.

I've not heard of a B2B on standby, they sense the voltages and turn on when required. This only happens when the engine is running.

If while driving your leisure batteries are discharging something is wrong. All the power should be coming from the engine and any solar and the batteries should be being charged.

 

[cmcardle75]

It only has the draw, when the fridge is on ! I usually have the B2B on standby when the leisure battery is fully charged from the solar panel Before a journey. However I now put it on when the fridge is on and this more than compensates for the 9 Amp draw, otherwise the leisure battery would have lost a percentage of its charge, after a reasonable journey.

It sounds like your fridge is programmed to come on when the engine is running, but the actual power feed is from the leisure side. Probably some hack to get round your distribution system electronics. I'd suggest not turning off your B2B.

 

[TheBig1]

electrically when the engine is running and the alternator charging both batteries and powering the fridge, they are in effect all connected. If the engine battery is drawing a lot of current, it is not unknown for the leisure battery to back feed it and support the fridge. Some but not all newer vans do indeed power the fridge direct from the leisure battery too

think of relays as a switch and when energised, the alternator passes current through that switch, but it is not intelligent and will allow current to pass in either direction. When testing the split charge on a van, or tow car, it is best to run the engine for a while before measuring actual current flow or voltage to allow for the surge of power taken from the vehicle battery by the starter to be at least in part replaced by the alternator. The voltage at each battery and the fridge should then be pretty much the same with allowances made for voltage drop across the lengths of wires

 

[cmcardle75]

electrically when the engine is running and the alternator charging both batteries and powering the fridge, they are in effect all connected. If the engine battery is drawing a lot of current, it is not unknown for the leisure battery to back feed it and support the fridge. Some but not all newer vans do indeed power the fridge direct from the leisure battery too

think of relays as a switch and when energised, the alternator passes current through that switch, but it is not intelligent and will allow current to pass in either direction. When testing the split charge on a van, or tow car, it is best to run the engine for a while before measuring actual current flow or voltage to allow for the surge of power taken from the vehicle battery by the starter to be at least in part replaced by the alternator. The voltage at each battery and the fridge should then be pretty much the same with allowances made for voltage drop across the lengths of wires

However, in the OP's case, this is not the case, as rather than a split charge relay, there is a B2B charger involved and no direct connection between the batteries. It appears the fridge is sensing the engine running (presumably through a D+ signal), but its element is connected to the leisure side, so it draws power from the leisure battery when the engine is running. This leads to a net draw on the leisure battery as the B2B charger has been disabled. I imagine a redesign where the fridge is connected to the engine battery side would be in order. Until then, the B2B should not be disabled.

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[Ian Bosman]

I thought I knew the answer to this, which is that the fridge connects to the starter battery/ alternator while driving.

But now I’m not so sure. I now have a lithium battery and a Sterling Power B2B charger. When this was installed, I think, to disconnect the split charge relay, one of the connections to the CBE thingy was disconnected. I have an app to monitor the Lithium battery charge/ discharge rates. While driving, there is a 9 Amp draw from the leisure battery, which presumably, must be going to the fridge.

Confused, but looking for enlightened guidance . . .

There should be a relay between the alternator and the fridge so that it only gets 12V power at the fridge when the engine is running thus not flattening the starting battery if you forget to change over to gas/mains. This has long been the arrangements that tuggers know about.

 

[cmcardle75]

There should be a relay between the alternator and the fridge so that it only gets 12V power at the fridge when the engine is running thus not flattening the starting battery if you forget to change over to gas/mains. This has long been the arrangements that tuggers know about.

It appears that part if working fine and the fridge only draws 12V power when the engine is running.

The issue is that it takes the actual power from the leisure battery rather than from the alternator. As there is no split charge relay and the B2B charger is disconnected, this results in a substantial net draw on the leisure battery.

 

[No-Dun-Roamin’]

If only their were good circuit, or wiring diagrams, it would be possible to see exactly what is going on and what is connected to where, and where things actually are. My hunch is that the disconnection to the CBE, to presumably disable the split charge relay, is contributing to what is happening, and that the fridge is directly connected to the wrong side of the split charge relay, wherever it might be. Probably not an issue when the CBE is fully connected. If if we not for the lithium battery app, I would have been non the wiser to what was happening. I now get round it by enabling the B2B when the fridge is on for longer journeys.

 

[cmcardle75]

If only their were good circuit, or wiring diagrams, it would be possible to see exactly what is going on and what is connected to where, and where things actually are. My hunch is that the disconnection to the CBE, to presumably disable the split charge relay, is contributing to what is happening, and that the fridge is directly connected to the wrong side of the split charge relay, wherever it might be. Probably not an issue when the CBE is fully connected. If if we not for the lithium battery app, I would have been non the wiser to what was happening. I now get round it by enabling the B2B when the fridge is on for longer journeys.

There is no reason to disable the B2B, unless it has the wrong settings for your battery chemistry. It may still be worth rewiring the fridge to the correct side, as its 9A are being taken off your maximum B2B charging capacity. (i.e. your 30A B2B is now a 21A B2B!)

 

[Potty]

What model is your fridge and is auto or manual select for fuel?

We had a similar problem on our Adria with a large draw on the leisure battery when the engine was running. We also thought that it must be the fridge but the dealer couldn’t figure out why it was happening. Eventually we contacted Adria direct and were told to check if there was a fuse in the fuse holder marked fridge and to remove it if there was. The van would not have left the factory with a fuse in there. There was, removed it, problem solved. The van had been serviced shortly before we noticed the problem.

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[the1andonly]

My Rapido also runs off LB. The Fridge is feed by a relay switched by D+. Did you fit the b2b yourself? No-Dun-Roamin’ . if so did you cut the r27 link on the CBE. I had the idea that a b2b was a fit and forget if all connected correctly.
We also had aggravation with a fridge recall having to downrate from the factory fitted 30A to 20A.

 

[No-Dun-Roamin’]

Hi the1and only - it’s a Sterling Power BB1260, 60 amp B2B charger. It was dealer installed and I’m sure it was all wired up correctly and properly set for the lithium battery setting. I don’t have a wiring or layout diagram and would like to be in a position to trace to whatever relays might be in place and the the D+ link, etc. I know that the BB1260 is wired such that it only automatically activates when the ignition feed is switched on and always reverts to standby when the ignition is off, per the option 2 wiring arrangement on the BB1260 pdf. I’ll need to double check the r27 link to the CBE, but I know that the furthest right hand lead to the CBE was disconnected by the dealer, if this makes sense. Also, on my last habitation check, the person doing it noted that there was no connection between the vehicle or leisure battery, which I would have hoped to be the case.
I went out last week for a few good days at Kinlochewe, and on route, I had set the BB1260 to be on float charge mode (since the leisure battery was fully charged by the PowerXtreme MPPT charger). With the fridge on there was no draw from the leisure battery, so things were looking good. However on the way home, I set the BB1260 to full charge and there was no draw initially from the fridge, but I think when it switched automatically to the conditionIng charge, there must have been a draw, because by the time I got home the leisure battery was down to 85% charge ! Because the battery was still charged, after being on hook up, the BB1260 seemed to be only charging at about 27 amps, initially.
Maybe I have a fault in the BB1260 charger, but there are no error messages, and the remote shows the different voltages on the vehicle and the leisure battery.
As it is currently working, my only way to be sure that the B2B charger provides a full charge, after being off grid for a few days, would be to put fridge contents into a cool bag and switch it off, so that nothing untowards happens, as it sometimes does when the fridge is switched over to battery, during travel.
Apologies to all whose eyes glaze over if they read this and try to make any sense, as it is now even more confusing . . .

 

[stevewagner]

I don't understand why you need to keep adjusting the B2B charger. I have the same one set up for my lithium batteries and you just leave to it's own devices. I cut the R27 resistor in my CBE DS300 unit and the fuse in the split charge part was overheating. I re-soldered the resistor and it works fine now but I never touch the B2B.

 

[Lenny HB]

I don't understand why you need to keep adjusting the B2B charger. I have the same one set up for my lithium batteries and you just leave to it's own devices. I cut the R27 resistor in my CBE DS300 unit and the fuse in the split charge part was overheating. I re-soldered the resistor and it works fine now but I never touch the B2B.

I think by putting the link (R27) back in you may have bypassed the B2B.

 

[stevewagner]

I think by putting the link (R27) back in you may have bypassed the B2B.

Still appears to be working

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[No-Dun-Roamin’]

Me thinks I need to understand the CBE aspects much better. Is the split charge relay integral to the CBE or is it completely separate to it. I’ll dig out the CBE booklet and hopefully can see where the R27 link is located.
Other than this quirky problem, everything in the van seemed tickety boo after months of being laid up !

 

[autorouter]

In the original wiring, the wire from the alternator/starter battery (now disconnected) carried the current for both the split charge relay/leisure battery and the fridge 12V element.

The B2B will I presume go straight to the leisure battery. The leisure battery is connected to the CBE distribution box, for all the previously connected loads, which is exactly what you want.

However the fridge connection is in the CBE box, and since the direct starter battery connection is no longer there, it will take power from the leisure battery, and therefore from the B2B.

If you want to remove that current drain, you could do what is done in many other MHs and have a separate wire from the starter battery to the fridge 12V power, switched by a relay triggered from the D+.

The 60A B2B current seems to be quite generous, so a 9A reduction of charging current doesn't seem to be a big deal. But if you really want to max out your leisure battery charging, it's worth fitting a separate fridge supply wire.

 

[autorouter]

Is the split charge relay integral to the CBE or is it completely separate to it. I’ll dig out the CBE booklet and hopefully can see where the R27 link is located.

Yes, the CBE box contains the split charge relay, the fridge relay and a few other relays like the habitation and awning light relays. Cutting R27 (I thought it was R37 but I'm not sure) will disable the split charge relay, but since the input to that relay is disconnected, it won't make any difference anyway.

 

[No-Dun-Roamin’]

I have just been perusing the CBE user manual (PX320-EX), which pertains to the control panel, the distribution box (DS520-EX) and the switching mode battery charger (CB516). It shows F7 as a 30amp fuse to give power to the AES (whatever that is) and the 3 way fridge, turning off automatically when the fridge is off). No diagram or reference to R27 resistor.
It does say with reference to the “electronic battery separator” that it is an electronic device controlled by the ignition switches on the battery parallel when the car battery is over 13.5V, and switches off when engine is or voltage lower than 12.2V. Is this effectively the split charge relay ? Since I have a sterling power trickle battery maintainer, the vehicle battery is always well topped up from the leisure battery and solar. Could it be this that is shorting or connecting the 2 batteries when the engine is on and pulling the lithium battery way down? If I could disable this somehow, I think it might be a key part of the problem/ solution.

 

[No-Dun-Roamin’]

With all the great advice, I think I am homing. In on a 2 prong solution . . .
1. Disable the so called “battery separator” by disconnecting R27 resistor (if I can hopefully find it).

2. buy a 30A ignition relay (again if I can identify a suitable one) and use this to connect the fridge 12V feed to the vehicle battery via the ignition relay.

I think both would be a belts and braces solution to the erroneous problems as I have experienced them.

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[autorouter]

It shows F7 as a 30amp fuse to give power to the AES (whatever that is) and the 3 way fridge, turning off automatically when the fridge is off).

Some 3-way fridges have manual selection of the power to the heater (12VDC, 240VAC or gas). Others have Automatic Energy Selection (AES).

It does say with reference to the “electronic battery separator” that it is an electronic device controlled by the ignition switches on the battery parallel when the car battery is over 13.5V, and switches off when engine is or voltage lower than 12.2V. Is this effectively the split charge relay ?

Yes. It's called different names - Schaudt call it the Battery Cutoff Relay for example.

Since I have a sterling power trickle battery maintainer, the vehicle battery is always well topped up from the leisure battery and solar. Could it be this that is shorting or connecting the 2 batteries when the engine is on and pulling the lithium battery way down? If I could disable this somehow, I think it might be a key part of the problem/ solution.

This battery maintainer will have a diode (electrical one-way valve) that only allows flow from the leisure battery to the starter battery. It won't be the cause of the problem. Unless it's failed of course, but that's very unlikely.

 

[the1andonly]

Sorry its R37 my memory

 

[autorouter]

With all the great advice, I think I am homing. In on a 2 prong solution . . .
1. Disable the so called “battery separator” by disconnecting R27 resistor (if I can hopefully find it).

2. buy a 30A ignition relay (again if I can identify a suitable one) and use this to connect the fridge 12V feed to the vehicle battery via the ignition relay.

I think both would be a belts and braces solution to the erroneous problems as I have experienced them.

If you disconnect R37 to disable the split charge relay, there's a good chance that you could reconnect the starter battery wire that the dealer disconnected. That would make the fridge work again, and would probably not cause any problems. You'd have to do further checks to be sure of this though.

If you don't want to chance that, you can still make use of the disconnected wire from the starter battery, connected to a relay, to supply the fridge.

 

[No-Dun-Roamin’]

Many thanks again for the great advice.
I can now see very clearly what to do from your advice and clear diagram. I’ll get to it today and snip R37. From the diagram, I’m sure that the dealer must have disconnected B1, the vehicle battery which was the probably the wrong, or a less effective way to disable the split charge relay.
As a contingency, I placed an order online for a Sterling Power Ignition feed relay (12V, 120A) last night. After I disconnect R37 and reconnect B1, I can see that there is a very good chance that it all might all come good. With the great detail you have very kindly provided, I can see where to wire the ignition feed relay if I really do need to do this to ensure the fridge feed is routed well and truly to B1.
Many thanks again for helping me to unravel what has been going on and it has all become much clearer with your help.
Off to Morvich, the week after next so will be a good chance to confirm everything is then all working as it should.

 

[the1andonly]

The full instructions for wiring a stirling b2b with acbe

https://www.12voltplanet.co.uk/user/downloads/Guide%20for%20fitting%20B2B%20charger%20with%20DS300%20for%20vehicles%20with%20%27smart%27%20alternators.pdf

Where did the dealer take the D+ sognal from?
On reinvestigation i have used a Signal though marked as D+ in the manual ia actualy ignition live.