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Battery advice sought


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Hi All,


I have been reading various battery threads that go back a while and have been particularly interested in Brambles' informed contributions. Here is my issue which I would welcome advice on.

I have a 2008, Fiat Ducato 2.3 based Burstner Aviano i640G A class MH. It has two leisure batteries located in a locker on the LHS of the vehicle.

The batteries appear fine but I need two batteries for other applications and my first thought was to use these and buy new ones for the MH.

OK that is the generality, here are the specifics! I WOULD post some pics but I can't for the life of me work out how to do it on an IPod. I will look on the PC later and follow up with some if I can!

The current batteries in the MH are: NUMAX LEISURE, starting and deep cycling. They are labelled LV25MF 100Ah C20.

The other two applications are

1. I am building a Toylander toy car for my Grandson (http://www.toylander.com) which will need a battery. Not sure what the power demand will be but you can bet it will be ultra deep cycled! It looks like a small starter motor driving the wheels through a gearbox.

2. I intend to tow our Smart Car and have bought a Trailer to which I intend to fit some secondhand Truma motor movers (my next project!). I will need a battery to fit to the trailer to power them this will be charged when I tow the trailer.

So, questions...

Are these batteries suitable for the above

What do I replace them with in the MH of similar or higher actual available capacity?


As an aside I saw this http://www.aandncaravanservices.co.uk/battery-technology.php and was quite impressed with the logic. Seems to confirm much of what Brambles has been saying?


Thanks in advance for the help and sorry for the ramble!




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I think you are over thinking this wanting to move batteries about. I would be inclined to leave the numax where they are and by the time you get the trailer and movers sorted out they may or may not still be in good condition. I would not think your trailer needs 100Ah so would buy a smaller battery for it but depends how far and how often you intend to move it. I have no idea how much capacity a caravan mover would use in practice but am sure I could maybe work it out and guessing it can't be much more than 10 Ah. This would leave a battery down say 10% and if mot being used for anything else then a dual purpose or indeed a starter like the Bosch S5 would be fine . ( I would still choose the Varta dual purpose over the starter though).


I would have thought most toy cars now would be using golf buggy type batteries. You do not need a great deal of power but you do need deep cycling and I would recommend something like the YUASA REC series, maybe a 22AH or 33AH, indeed might work out reasonable to use two REC22-12 in parallel giving 44Ah. These are AGM batteries so suitable for safety (non spill) as well, and I have not found better for lasting in small wheelchairs being used all day every day. Looking at one of the landrover cars it mentioned a 33Ah battery.


I am not really trying to completely answer your questions but give food for thought.

(Food!!! where where. - Editor)


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May I add that you already have the starter battery in your Bürstner, plus 200Ah of installed leisure battery, to re-charge from the alternator. The cable from the alternator to the battery on the trailer will be long, so will need a large section cable (plus an equally large section cable at least to a good earthing point on the Bürstner chassis), but even so, by the time it has been through the trailer electrical connection (which will somewhat limit the cable gauge you can use), I suspect the mover battery won't be getting much of a charge. So yes, I agree with Brambles, use the smallest capacity battery you can get away with for the mover. Otherwise, something, somewhere, just isn't going to get adequately charged! You may have several batteries, but there is only one alternator with which to charge them.
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While a Caravan Motormover system can draw as much as 280amps on the very big vans and take 10 minutes to manoeuvre, a small car on a Trailer is likely to be only about 90amps, maybe a bit more going up an incline?. But even so if you run continuously for about 10 minutes when getting the Trailer into position that is a lot of power taken out of the battery in a short space of time. While the overall power drain might not be that great, it is the short duration that is the issue. Not one that a conventional Leisure battery copes with as well as a Starter battery, which is what I would favour. I would also suggest a fairly big battery, like 100Ah to help dissipate the heat and load?

I would not use the old leisure batteries that are likely to fail under the first exertion?


I think a bigger problem will be building a water proof box to protect the Mover Electronics with so many cables needing access into the box? The Ariel wire should be ok coiled inside as you will have a lot less metal around than a Caravan to attenuate the signal?.


I don't know what Starter Motor you plan on using in the Toy but I would not expect current draw to be high as the loading should be light so your old Leisure batteries should cope?

However, one consideration is the weight difference between most leisure batteries and a suitable smaller battery? My sons truck weighs a Ton and while I really don't want to lift it, I always find myself struggling over things to get it and out the back of the Garage!! Brambles Yuasa batteries make good sense with an AGM charger.


As for the charging of the Trailer battery there are modules you can buy that boost the voltage from the Alternator, a Schaudt WA1204??, to compensate for the voltage drop over long cable runs. Such as from the front of a Car to the very rear of a big Caravan. Some of the Schaudt EBL units already have this functionality built in.

One of these Voltage Boost units would allow you to get away with using thinner cabling, like standard 7 core Trailer cable as opposed to very fat cable to reduce voltage drop? I suspect it would also give you better charge control than just linking a wire off the habitation batteries which might lead to overcharge of the Trailer battery? Taking a wire direct from the Habitation batteries might result in the Trailer battery sharing 'big amps' from the Alternator (for example driving off when the Habitation Batts have been run down low overnight) when the trailer battery is almost fully charged?


Most we have seen mount the battery box at the front of the A frame with all the weight over the Jockey wheel which doesn't ride well on even the best surfaces. Also gets in the way of the winch.

We would suggest mounting the battery box behind the back axle as this will counterbalance the trailer when empty making it a lot easier to manoeuvre by hand which is a lot quicker than the slow Truma mover unit. The Varta SD H3 is a low height unit that could be mounted 2" above the trailer deck, so still out of the way of a low exhaust, with only 4" hanging below the deck giving good ground clearance.





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First of all thank you all for your expert advice. I am always gladdened by the willingness of people to help! Of course, I am willing too but being a mining engineer my expertise is not often called on!


I will try to attach a few pics of the trailer. Basically, the previous owner fabricated a battery box under the deck already, Its over the axle which is not where i would have put it but its fine. It is a bit limited in lenght. The max length of battery would be 240mm (by 190mm wide and 340 deep).


The winch will be going anyway, I dont need it and its currently facing the "wrong" way because it was used to pull the trailer up a steep drive.


The MH will be wired with a full 13 pin plug and a split charger.


Actually I am not too worried about the box, there are several IP66 or greater boxes around. I think I will mount it where the winch currently is. There is plenty of room on the trailer with a Smart car and i need to find where to stop it to give me the correct noseweight yet.


Re batteries I am going to take the advice and keep the Numax ones in the MH for now and buy two others for the Car and the trailer. I think a 50 or 60 Ah will be plenty for the trailer. Its really just belt and braces this motor mover idea, inspired by a sudden rush of blood to the wallet when i saw a bargain secondhand set!



ps miserable failure with the photos, sorry

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