# sterling battery to battery charger



## 118819 (Dec 16, 2008)

can you fit a sterling battery to battery charger on a mh with its own split charge system (2008 autosleeper) is it ok to just connect it to van battery and one of the leisure batteries .
many thanks


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## time-traveller (Apr 23, 2007)

I hope I understand the question by saying that the factory fit split charge relay is made redundant by the Stirling batery-to-battery charger as effectively it replaces it. The main output from the alternator is fed into the Stirling unit and the output to each battery (starter and auxiliary) is fed from independent terminals from the Stirling. The Stirling then controls the output to each battery independently. Does that make sense to you? I have had several Stirling units and I can recommend them as a much more sophisticated and efficient system of charging the auxiliary battery than the rather inadequate split charger. The problem of battery charging in motorhomes really starts at the alternator as it was never designed to cope with the rather peculiar power requirements of a motorhome. The Stirling unit effectively modifies the performance of the alternator to suit - and very effective it is, too.



pands10 said:


> can you fit a sterling battery to battery charger on a mh with its own split charge system (2008 autosleeper) is it ok to just connect it to van battery and one of the leisure batteries .
> many thanks


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## DABurleigh (May 9, 2005)

Yeah - what he said


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## trek (May 1, 2005)

I think I would be inclined to disconnect the original factory split charger and then fit the Sterling battery to battery charger


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## Jean-Luc (Jul 21, 2005)

When fitting a Sterling B to B charger to my Rapido I had the problem of not being able to 'replace' the split charge relay as it seemed to be built in to the circuity of the CBE kit used by Rapido. Stirling Power, while very helpful seemed to be unable to provide a difinitive solution which would not colflict with the origional equipment. The CBE unit also monitors the vehicle battery and will send it a charge if required when on EHU. 
All this lead me to be concerned about creating a circular circuit! resulting in the 14.8V from the B to B unit getting into the vehicle electrics and upsetting the engine management etc.
My solution was to leave all the original stuff in place and fit a relay on the output from the habitation battery. This isolates all the 12V habitation stuff, when the engine is running, from the habitation batteries, and the 14.8 V from the B to B from everything except the habitation batteries.
Since fitting the B to B this way last Spring I have spent over 100 nights away, often with the TV, lights, etc. on of over 5 hours, without EHU and never had any battery problems.
An interesting side effect of the CBE's management of the engine battery is that when on EHU it will bring it up to 12.8/13.0V, this kicks the B to B into life, it will auto start and start supplying a float charge of 14 V to the leisure batteries!!


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## time-traveller (Apr 23, 2007)

Very ingenious. I like it. Something to remember should I ever meet this problem. I wonder how many other makes of motorhomes incorporate integral split chargers like this.



Jean-Luc said:


> When fitting a Sterling B to B charger to my Rapido I had the problem of not being able to 'replace' the split charge relay as it seemed to be built in to the circuity of the CBE kit used by Rapido. Stirling Power, while very helpful seemed to be unable to provide a difinitive solution which would not colflict with the origional equipment. The CBE unit also monitors the vehicle battery and will send it a charge if required when on EHU.
> All this lead me to be concerned about creating a circular circuit! resulting in the 14.8V from the B to B unit getting into the vehicle electrics and upsetting the engine management etc.
> My solution was to leave all the original stuff in place and fit a relay on the output from the habitation battery. This isolates all the 12V habitation stuff, when the engine is running, from the habitation batteries, and the 14.8 V from the B to B from everything except the habitation batteries.
> Since fitting the B to B this way last Spring I have spent over 100 nights away, often with the TV, lights, etc. on of over 5 hours, without EHU and never had any battery problems.
> An interesting side effect of the CBE's management of the engine battery is that when on EHU it will bring it up to 12.8/13.0V, this kicks the B to B into life, it will auto start and start supplying a float charge of 14 V to the leisure batteries!!


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## time-traveller (Apr 23, 2007)

Yes - that is the only way to do it



trek said:


> I think I would be inclined to disconnect the original factory split charger and then fit the Sterling battery to battery charger


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## blondy (Aug 23, 2007)

On my Burstner elegance no mods were made to existing system, just connect B/B charger to both sets of batteries, been perfect, except battery gauge on controls not acurate. As was said now no prob away from EHU.


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## DABurleigh (May 9, 2005)

Just for the sake of completeness, another variation for a different purpose was that I wired the B2B in series with the split-charge relay then had a remotely switched suitably rated contactor take the B2B out of circuit when I wanted to run mains aircon on the move on a positive energy budget. The B2B stuck in a ~45A charging cap when under these conditions the alternator would give out more.

Dave


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