Split Charge Relay Location (1 Viewer)

Nov 30, 2009
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Hi, I am looking to fit one of the Sterling battery to battery chargers.

Looks a fairly straight forward job just choosing the correct cable and fuse sizes :thumb:

The one part of the installation i am stumped on is the removal or disconnecting of the original split charge diode or charge relay system already installed in the motorhome.

This has to be disconnected somehow to avoid conflict with the Sterling charger.

Our MH is based on the old style Fiat Ducato..... 2006 model.

I could trace it back from the leisure battery feed but i am sure someone will know where it is located :helpsos:

Many Thanks.....Ralph
 

canopus

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Hi Ralph

The one on our Rapido plus the relay for the tow bar are located under the van towards the rear. The relays are mounted in individual plastic enclosures with screw off lids. My split charge relay failed due to water ingress. I replaced the relay and then sealed the lid with silicone sealant :Smile:
 

haganap

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It doesn't "have" to be removed, many I know haven't, although on mine a relay is fitted to prevent the fridge being confused and creating a circuit within a circuit.... The relay is fitted via the live feed therefore bypassing the normal workings until back on hook up :thumb:


Oh but to answer your question, mine is actually under the bonnet

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Ralph-n-Bev
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It doesn't "have" to be removed, many I know haven't, although on mine a relay is fitted to prevent the fridge being confused and creating a circuit within a circuit.... The relay is fitted via the live feed therefore bypassing the normal workings until back on hook up :thumb:


Oh but to answer your question, mine is actually under the bonnet


Hi Paul i dont see how it can stay as surely you will end up with two charge feeds to the battery bank.
I would have thought for this 4 stage charger to work properly it would need one feed only to work correctly ??.

Also, will removing this relay stop the fridge working on 12v whilst driving ?

I would hate to arrive to warm beer :beer:

Thanks.....Ralph
 

magicsurfbus

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The one part of the installation i am stumped on is the removal or disconnecting of the original split charge diode or charge relay system already installed in the motorhome.

This has to be disconnected somehow to avoid conflict with the Sterling charger.

Our MH is based on the old style Fiat Ducato..... 2006 model.

I may be missing something here but in our 2005 Fiat Ducato-based CI camper the battery charging system and relays appear to be incorporated into the fuse board that sits in a black box behind the driver's seat. The relays are hard-wired into the board and can't be messed with.

When we were having trouble with the engine battery state being monitored inaccurately by the control panel and the fridge switching on and off, all the relay activity was in the fuse box. The leisure battery wasn't being charged either, and when it was fixed it was the fuse board and the earth connection that needed dealing with. None of the numerous people who investigated the fault looked anywhere else for charging relays.

But I'm not an auto electrician so I may be completely wrong here.
 
Last edited:
Jan 24, 2010
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i fitted a second hand one a couple of weeks back and did ponder on the split relay bit...but in the end decided not to hack into more wiring and see what happened on a good run up to the Chester meet and back last weekend

everything is fine, Fridge was fine, batteries FULLY charged (extra 50ish amps) and nothing blown or not working:thumb:

there may well be a difference in fitting one in a euro van versus a UK one, as UK ones cut the hab electrics when the engine is on which (most if not all) euro ones dont, so the wiring may well be different on that front

our 12v electrics all run to and from the CBE distribution board,including the split relay feed, the fridge is powered from this board too. I haven't found a direct path from the split relay to the fridge either, other than via the dist board - so my assumption is that it doesn't matter where the 12v comes from the dist board manages what the fridge gets on the move

May be worth a call to sterling for a definitive - which i was going to do if there was any problems but as i have none i haven't needed to...yet:Eeek:

My van is a 2008 Fiat BTW and the relay stuff is in the pillar by the drivers seat

best £100 i have spent on the van::bigsmile:

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haganap

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Hi Paul i dont see how it can stay as surely you will end up with two charge feeds to the battery bank.
I would have thought for this 4 stage charger to work properly it would need one feed only to work correctly ??.

Also, will removing this relay stop the fridge working on 12v whilst driving ?

I would hate to arrive to warm beer :beer:

Thanks.....Ralph

Ok, firstly as Bungy has shown as many others will testify it will work. It will dump additional amps in to your batteries. It's what I was going for, except, when speaking o Jon & Chell he explained it to me...

Yes it will work, but not correctly. This is because that I think it's job is to also monitor the batteries, if the fridge is on, this interferes with the way it works as the batteries are providing the fridge and therefore not being monitored correctly and creating a circuit within a circuit. Fittings relay allows the fridge to remain working but having its power consumption monitored via the b2b.

It makes it difficult for the b2b to understand everything that's happening, hence a possible overcharge. I have my Solars isolated too so that when I'm driving down the road they too are isolated.

I'm not the best person to explain this, maybe a pm to jon&chel might be better, after all that's his job, what I do know is after his numerous explanations to me I eventually understood that to have two circuits doing the same job was not correct. This meant the safe way was for a relay to be fitted, although. Know lots that don't with no problems.

As magic surf bus says on. One the relay is in the bonnet compartment proving that manufactures can put them any wheree:Smile:
 

JockandRita

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Ralph,

I fitted a Sterling B2B in our Ducato based 99 Hymer, having first discussed the matter verbally with Sterling, and then by email with Schaudt in Germany. I did not need to disconnect, not introduce any relays.
Like Paul above, I too have had the same conversation with Jon&Chel, and was about to drive to Kings Lynn for him to do a wiring job for me, however, after taking readings with a mutimeter, before and after connection of the B2B, it turns out that there isn't the same conflict with our charging system and the B2B, as Jon has experienced on other MHs. Jon was interested to know the results, and pleased too that there wasn't any conflict showing. Our charging and distribution system is the Schaudt Elektroblok, which deals with everything 240v and 12v.

The B2B is a cracking piece of kit, and greatly enhances the ability to wild camp, with total independence from mains hook up. ::bigsmile: Good luck with the installation. :thumb:

Regards,

Jock.
 

jonandshell

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OK I'm posting this from a phone so I'll be brief........

Ralph you are correct in your assumption that a smart charger will only work on an isolated battery bank.
You have no need to remove your split charge relay, this will cause more problems than it solves, possibly warm beer!
All you need do is fit the Sterling as per the instructions, paying attention to the recommended cable thicknesses. In order to isolate the leisure battery during charging, fit a 70 amp 5-pin relay into the original leisure battery positive cable.
Use the 'normally closed' terminals so that the battery is connected to the caravan electrics when the engine is stopped. Use an ign live to energise the relay, therefore when you start your engine, the relay goes open-circuit, the leisure batttery is left connected to the Sterling unit alone.
Meanwhile, your original split charge relay will continue to supply your fridge and caravan electrics whilst your engine is running.

Hope this makes sense!:thumb:

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Ralph-n-Bev
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Gone straight over my head . :ROFLMAO:
But no doubt Ralph will get it. Hes already gone to work. Skidding down the streeton the black ice , in his pick up at 7am.
He will catch up with the thread when he gets back tonight. :thumb:
 
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Ralph-n-Bev
Nov 30, 2009
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OK I'm posting this from a phone so I'll be brief........

Ralph you are correct in your assumption that a smart charger will only work on an isolated battery bank.
You have no need to remove your split charge relay, this will cause more problems than it solves, possibly warm beer!
All you need do is fit the Sterling as per the instructions, paying attention to the recommended cable thicknesses. In order to isolate the leisure battery during charging, fit a 70 amp 5-pin relay into the original leisure battery positive cable.
Use the 'normally closed' terminals so that the battery is connected to the caravan electrics when the engine is stopped. Use an ign live to energise the relay, therefore when you start your engine, the relay goes open-circuit, the leisure batttery is left connected to the Sterling unit alone.
Meanwhile, your original split charge relay will continue to supply your fridge and caravan electrics whilst your engine is running.

Hope this makes sense!:thumb:

Thanks for the detailed explanation but you lost me at the highlighted point in blue.

BTW our van electrics being euro still work when driving ::bigsmile:riving2: in fact so dose the oven which means my tea is ready when i arrive :thumb:

I also have solar...will this need isolating whilst driving??

Thanks.....Ralph

Only joking about using the oven whilst driving......Honest :whistle:
 

jonandshell

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Thanks for the detailed explanation but you lost me at the highlighted point in blue.

BTW our van electrics being euro still work when driving ::bigsmile:riving2: in fact so dose the oven which means my tea is ready when i arrive :thumb:

I also have solar...will this need isolating whilst driving??

Thanks.....Ralph

Only joking about using the oven whilst driving......Honest :whistle:

5 Pin relays have 5 pins!

2 of these are the pos and neg for the coil which energises to switch the relay.

There is one 'common' pin.

There is a 'normally closed' pin. This connected to the common when the relay is NOT energised. When the relay is energised, this pin is disconnected from the common pin.

Finally there is a 'normally open' pin. This is disconnected from the common pin when the realy is NOT energised. When the relay is energised, this pin is connected to the common pin.

Now, by utilising the coomon and normally closed pins of the relay, the relay can act as an ignition-switched battery isolator to disconnect the leisure battery from the caravan electrics whilst the Sterling unit is charging them.

Your solar should be connected on the other side of this relay to avoid the solar ouput being sensed by the Sterling unit whilst it is charging.

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Ralph-n-Bev
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5 Pin relays have 5 pins!

2 of these are the pos and neg for the coil which energises to switch the relay.

There is one 'common' pin.

There is a 'normally closed' pin. This connected to the common when the relay is NOT energised. When the relay is energised, this pin is disconnected from the common pin.

Finally there is a 'normally open' pin. This is disconnected from the common pin when the realy is NOT energised. When the relay is energised, this pin is connected to the common pin.

Now, by utilising the coomon and normally closed pins of the relay, the relay can act as an ignition-switched battery isolator to disconnect the leisure battery from the caravan electrics whilst the Sterling unit is charging them.

Your solar should be connected on the other side of this relay to avoid the solar ouput being sensed by the Sterling unit whilst it is charging.

Looks like a job for an auto sparky to me.

Although i do find it easier to follow a wiring diagram preferably a colored one.

Just need to get my head round wiring up relays and it sure it will make more sense.
Where can i buy the required relay ?

Thanks again.... :thumb:
 

jonandshell

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Et, Voila!:thumb:

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jonandshell

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Sorry, resized!!!
 

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haganap

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Ill just take 1/2 a cider for my introductory fee :winky:

looks like your very much in love, Haggers electrical dating.....:Cool:
 
OP
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Ralph-n-Bev
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Ill just take 1/2 a cider for my introductory fee :winky:

looks like your very much in love, Haggers electrical dating.....:Cool:

Paul you know you and Nickie are always welcome for a cold beer / Vodka / Whisky :winky:

Dont feel jilted though mate he hasn't seen how ugly i am yet :Sad:.

Must say the drawing makes the job alot easier than following instructions.

Thanks to everyone for there input especially John :smalllove: xxx

Ralph
 

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