# Connecting leisure batteries to Engine Batteries



## jusjess13 (May 17, 2011)

I want to connect my Leisure batteries to the engine batteries, so that the engine batteries don't go flat.
Has any body connected the 2 batteries up and used a relay that de-energies when the ign is switched on to isolate the batteries, so that no damage is caused?
Is there a product on the market for this to be done or it just as easy to wire it up my self?
The only problem i see is that when your wild camping, you could possibly drain the start batteries or bring the start batteries to the level of the leisure batteries.

Thanks
Dave


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## wakk44 (Jun 15, 2006)

You need one of these


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## Techno100 (May 8, 2010)

wakk44 said:


> You need one of these


Cheaper here

or similar cheaper still


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## 747 (Oct 2, 2009)

Even cheaper here  

Run a wire from + to + and put a 10 amp fuse inline.

Remember to remove the link before starting the engine. It will only blow the fuse if you forget. That is why the fuse is very important. :wink:


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## Perseus (Apr 10, 2009)

There is exactly what you are looking for made and distributed by CAK Tanks. Priced at about 30 quid it is very highly recommended by many users on here.


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## Techno100 (May 8, 2010)

Yes I'll second that! I have one fitted but it is only any good if you're on hook up OR have solar. If not? then you need a Vanbitz device or similar.

The CBE unit made by CBE (Italy) and sold by CAK tanks works differently and for a different purpose and only sends excess charge to the engine battery once the leisure has reached 13.6 volts

"The battery master was designed to support the cab battery at the expense of the leisure battery by transferring charge at anything up to 1.1 amps whilst ever the cab battery is half a volt lower than the hab.
This was primarily for storage situations with no hook up or solar BUT it will work with solar with the limitation of the small charge rate. Price circa £65 ebay inc delivery

The CBE is designed to maximise the benefit of solar by sending charge at up to 4 amps to the cab battery once the hab battery has reached 13.6 volts (it only has to reach that voltage for an instant to begin transferring charge) and continues to transfer charge until the leisure battery is sensed to have dropped to 12.6 (wont in daylight due to solar input) i.e. it doesn't switch off just because it drops to 13.5 . Before fitting one of these my cab battery was always a lower voltage than my hab but now they are all fully charged and ready to go. 
Price circa £27 + P&P

Conclusion
The CBE is useless if you dont have solar or hook up

The battery master is perfect if you dont have solar or hook up"
TECHNO


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## mr2 (Feb 26, 2009)

wakk44 said:


> You need one of these


Concur with above. Have had one connected for almost 4 years successfully between 2 leisure batteries and vehicle. Helps to have a solar panel!


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## FoweyBoy (Dec 7, 2006)

Could someone please provide a link to the CBE unit in CAK Tanks or a name I can use to trace it in their catalogue?

Many thanks.


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## Techno100 (May 8, 2010)

BCM12
Bottom right on last cbe page
http://www.caktanks.com/files/cak_c...ections/77-90_CAK_2010_Electrical_Section.pdf


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## joedenise (Jul 20, 2007)

Surely that's not what he is asking for. He's just looking to connect the leisure battery to the vehicle battery so it doesn't go flat.

Joe


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## sprokit (May 1, 2005)

FoweyBoy said:


> Could someone please provide a link to the CBE unit in CAK Tanks or a name I can use to trace it in their catalogue?
> 
> Many thanks.


http://www.caktanks.com/files/cak_c...ections/77-90_CAK_2010_Electrical_Section.pdf

Scroll down until you find it - Page 81 - right hand side

Keith (Sprokit)


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## Techno100 (May 8, 2010)

joedenise said:


> Surely that's not what he is asking for. He's just looking to connect the leisure battery to the vehicle battery so it doesn't go flat.
> 
> Joe


Covered in post no 4 Joe but op is not participating :roll:


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## 747 (Oct 2, 2009)

How long is he parked up for??? 8O 

The ethic of wildcamping is to only stay one night or two at most. If he is wilding long term in one spot then he might cause problems for others following him.

Looks like he has gone anyway. :roll:


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## FoweyBoy (Dec 7, 2006)

This is one arrangement for keeping vehicle battery charged while not on the move:-

http://www.motts.org/BRIDGING FUSE.htm

With a 10amp fuse and wiring to match what would happen if you connected a flat vehicle battery to a well charged leisure battery? Would the current flow exceed 10amp and blow the fuse?

The scenario I was envisaging is wild camping with solar charging to the leisure battery and getting a flat vehicle battery. What would happen if I connected the two batteries?


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## Snelly (Aug 20, 2005)

The battery Master is the way to go... use one of MHF traders who offer a discount for subscribers to save yourself a few quid


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## 747 (Oct 2, 2009)

I cannot understand the worry about engine batteries going flat when wilding. Even on the new vans with small battery draining, you would have to wildcamp a long time (without moving) before getting to that stage.

If you have solar, just use the cheap and cheerful Motts.org solution.

ps, connecting to a discharged engine battery should not blow a 10 amp fuse in my opinion. The scenario is so rare that nobody will probably have a practical knowledge of the consequences.


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## jusjess13 (May 17, 2011)

Hi i am still here.

i have been looking at all the replies, so many people have differnt opinions, which is what it is all about.

Thankyou all very much.

Dave


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## FoweyBoy (Dec 7, 2006)

747 said "I cannot understand the worry about engine batteries going flat when wilding. Even on the new vans with small battery draining, you would have to wildcamp a long time (without moving) before getting to that stage."

I have an Autosleeper Nuevo with a switch to disable the 20 min radio cutout. The problem is while the switch is on the radio is left on standby (although not working) using vehicle battery current. If you forget to turn it off you can drain the vehicle battery in a few days. Only done it once on a campsite where I could use mains charger. If wildcamping or on site with no electricity if I forget I could drain the vehicle battery. Hence my original question.


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## 747 (Oct 2, 2009)

I am not disputing what you say but that surprises me. If it were me, I would be running the radio off the leisure batteries.

Well...... thats progress I suppose. I wonder why the older vans like my 52 reg do not suffer with the same problem. Does anyone know?


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