# Fitting extra leisure batteries



## GEMMY (Jun 19, 2006)

I've searched, but our incomprehensible search system is :?: :?: :!: 

Can someone head me in the direction of the wiring diagram for 3 leisure batteries fitted in parallel.

Ta !

tony


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## jedi (Nov 22, 2007)

Though this is only for two, Tony, it might help:

http://www.motts.org/second leisiure battery.htm

Jed


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## joedenise (Jul 20, 2007)

Just connect all negatives together and then all the positives

joe


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## GEMMY (Jun 19, 2006)

Cheers Jed, I found that on google, the diagram I'm after was for 3 and specific about pos and neg leads from the electroblock. 

tony


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## GEMMY (Jun 19, 2006)

Thanks Joe but that diagram was specific that it wasn't that easy to do it properly

tony


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## joedenise (Jul 20, 2007)

Depends what you mean by properly as long as you don't + to_ it will work :? 

joe


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## GEMMY (Jun 19, 2006)

Yes Joe :lol: , I know that works, but apparently it puts undue strain on the first battery being constatly charged whilst waiting for the trickle down down effect to happen to bat No2 and No3  

tony


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## listerdiesel (Aug 3, 2012)

GEMMY said:


> Yes Joe :lol: , I know that works, but apparently it puts undue strain on the first battery being constantly charged whilst waiting for the trickle down down effect to happen to bat No2 and No3
> 
> tony


Unless you have truly giant batteries and serious charging currents in the hundreds of amps, it doesn't really matter.

If you have three batteries in parallel, the resistance of the interconnections is the only significant item that will affect the charging.

As long as you use 25sqmm / 35mm sq mm or even 50sq mm if you can get some in welding cable for the links, it will not make any difference.

I don't know who started this off, but there are more problems with paralleling batteries than how they are connected. In a perfect world you would have steering diodes for both charging and discharging current paths when connected in parallel, but in practice they are rarely used.

Peter


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## joedenise (Jul 20, 2007)

I knew someone who knew what they were talking about would come along :!: 

the last bit lost me though :? 

joe


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## joedenise (Jul 20, 2007)

And I didn't start it mister it was Tony honest

joe


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## GEMMY (Jun 19, 2006)

Don't look at me. :lol: :lol: :lol: 

tony


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## Techno100 (May 8, 2010)

Mmmmm 35mm for side by side 8) 
http://www.ebay.co.uk/itm/350183286975?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649


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## GEMMY (Jun 19, 2006)

Ok. everyone, I've found what I was looking for:

http://www.smartgauge.co.uk/batt_con.html

System No2 

tony


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## listerdiesel (Aug 3, 2012)

joedenise said:


> the last bit lost me though :?
> joe


Steering diodes are fitted when you have multiple batteries in parallel, or multiple strings (more than one battery in series) in parallel.

They prevent inter-battery discharging due to (for example) a failed cell or battery.

On the charging side they enable individual batteries to sit on charge at slightly different voltage levels, without being forced to sit at the same voltage.

Peter


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## listerdiesel (Aug 3, 2012)

GEMMY said:


> Ok. everyone, I've found what I was looking for:
> 
> http://www.smartgauge.co.uk/batt_con.html
> 
> ...


Tony:

If you were whacking 100A in and out of your battery all day, you'd be looking at a far bigger set than three in parallel!

The fact is that you are not, and for your average lead-acid battery it will not sit on charge at 100A either, promise, I know it won't!

It's easy to print such a dissertation quoting loads of figures, but your AVERAGE user ain't going to see those levels of current for any significant period of time, and at the lower currents it is insignificant.

Up to you, we have much bigger and uglier batteries in service, and they are always connected in ladder-parallel connection.

If anyone is going to argue about 0.0015 ohms resistance in connecting leads, you need to get a life.

Peter


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## joedenise (Jul 20, 2007)

Peter - I thought that was what you were saying but I wasn't sure.

Joe :roll: :lol: :lol:


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## listerdiesel (Aug 3, 2012)

Techno100 said:


> Mmmmm 35mm for side by side 8)
> http://www.ebay.co.uk/itm/350183286975?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649


Heatshrink would have been nicer than sticky tape, but they'd be fine.

Peter


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## GEMMY (Jun 19, 2006)

And:

http://www.motorhomefacts.com/ftopict-134316-battery.html+wiring

tony


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## Zebedee (Oct 3, 2007)

GEMMY said:


> Ok. everyone, I've found what I was looking for:
> 
> http://www.smartgauge.co.uk/batt_con.html
> 
> ...


Hi Tony

I wouldn't pay much attention to what they are saying on that guide!

_"The power from the next battery up has to travel through the same main connection leads but in addition also has to travel through the 2 interconnecting leads to the next battery. The next battery up has to go through 4 sets of interconnecting leads. The top one has to go through 6 sets of interconnecting leads. So the top battery will be providing much less current than the bottom battery."_

All this means is that the current has to travel a little bit further from the most distant battery, which is one reason why it is advisable to position them as close together as possible.

BUT the distance from the nearest battery to the charger unit or any of the equipment will be many times the length of the inter-connecting leads, and it will be much thinner cable too.

Mine are wired together with cable that could power a small town . . . until it joins up with the connection to the original battery which is like a piece of string in comparison.

Lister is right. _"As long as you use 25sqmm / 35mm sq mm or even 50sq mm if you can get some in welding cable for the links, it will not make any difference. "_ I would agree entirely that it will make no practical, measurable difference, and in any case the usage figures they gave don't refer to any motorhome setup I can think of. :roll:

Dave


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## GEMMY (Jun 19, 2006)

tony


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## listerdiesel (Aug 3, 2012)

I have to say that there is so much 'smoke & mirrors' stuff in the leisure/consumer industry, it makes you want to weep!

If you want to see some real battery technology, have a look at things like the Zebra battery, horribly expensive, totally impractical for anything but serious infrastructure or military use, but very interesting.

http://en.wikipedia.org/wiki/Molten_salt_battery

You have to heat it up to something like 200 Deg C before it starts working, batteries are nominally 50V or so. Beta Research came out of British Rail if what I was told was correct.

We built a 100kW (650V 150A) charger to enable trials to be run on those batteries, that was a real beast to work around, we built a 300 gallon tank in stainless with 16 X 9kW immersion heaters to test it.

Great fun!

Peter


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## Mandale (May 18, 2011)

listerdiesel said:


> joedenise said:
> 
> 
> > the last bit lost me though :?
> ...


 we use a CBE BDS 150 for two leisure batteries. As Peter says, this type of system works really well. CBE only make this system 
for two batteries, do you know of a system which will cater for more than two Peter.


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## listerdiesel (Aug 3, 2012)

Do you mean for two 'separate' batteries or two paralleled batteries?

Peter


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