# Using Leisure Batteries off EHU.



## TheWoodentops (Jul 10, 2013)

Just purchased our first MH, which has a new 85 amp leisure battery. I would like to know if it is a simple procedure adding another 85 amp. Someone has told me that all I need to do is connect a cable from positive to positive and negative to negative between the two batteries.
There is space next to the original battery to take the new one.

Also I would like advice on how long I can expect from these two batteries while using 12 volt only. I understand that the fridge will need to be switched onto gas, so it would only be for lighting, fan for gas heating, TV and microwave (through inverter - 800w ), and phone chargers, etc.

Hoping someone can help me with this. KB.


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## MYFANWY1 (May 9, 2011)

Hi there, you can just connect like you said, but they must be the same amp, and you have to let the van know the is two battery. Check with a dealer, I had it done. Not much help I know but better to be safe than sorry. Eddie.


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## andrewball1000 (Oct 16, 2009)

The best way to find out how long your batteries will last is visit a campsite but not plug in to EHU till you need to.


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## TheFellTerrier (May 19, 2008)

TheWoodentops said:


> Just purchased our first MH, which has a new 85 amp leisure battery. I would like to know if it is a simple procedure adding another 85 amp. Someone has told me that all I need to do is connect a cable from positive to positive and negative to negative between the two batteries.
> There is space next to the original battery to take the new one.
> 
> Also I would like advice on how long I can expect from these two batteries while using 12 volt only. I understand that the fridge will need to be switched onto gas, so it would only be for lighting, fan for gas heating, TV and microwave (through inverter - 800w ), and phone chargers, etc.
> ...


You should be fine installing a second leisure battery in the way you have suggested using sufficiently heavy cable.

Make sure the batteries are well secured and vented to the open air.

Your 800w inverter is unlikely to be enough to run a microwave oven and will drain your batteries very quickly.

Difficult to say how long the fully charged batteries will last but you should have approx 85ah available (ie 50% capacity) and should be able to calculate the time from the power of the items being used.


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## KeithChesterfield (Mar 12, 2010)

As we all say when we're not 100% certain 'I'm not an expert but …...'

Fitting a Solar panel would probably be of more use than fitting an extra battery, especially if the battery is newish and in good condition, and wouldn't cost a great deal more.

Do search for 'Solar Panels' on these forums for a great deal of advice and opinions.

:wav: :wav: :wav:


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## listerdiesel (Aug 3, 2012)

A second battery should be connected as you describe, technically 'in parallel', this maintains the same 12V supply voltage but the available capacity is the sum of the two battery's capacities.

We have three 55AH batteries on the trailer, two on the domestic side and one for the rear where the engine is kept. We run heating and cooker/fridge on gas, plus the water heater. The heaviest current draw is the Avtex TV, plus a bit for the satellite receiver.

Lighting and TV are the biggest users of power, so get into L:ED lighting when you can, keep an eye on the battery voltage, hopefully you have something that tells you if the battery is getting low?

Solar panels are a very good idea as suggested above, it's a bit more involved but a VERY useful addition. Look in the Solar Panel section for loads of posts on the subject.

We fitted 4 X 80W panels and two controllers, mainly as we have a largish winch to power which most motorhomes don't have :lol: so that has its own battery which is independent from the other domestic stuff.










The right-hand pair are parallelled, the left-hand one is for the winch.

This is the earlier arrangement when all 12V stuff was on the two parallelled batteries:










Peter


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## Mrplodd (Mar 4, 2008)

Don't think you will be able to run a microwave off your inverter, they take a MUCH higher initial load on start up than it says on the tin. 

TV etc shouldn't be a problem, I run a 19 inch TV for many hours off two x 110ah batteries via an inverter (5 hrs is the longest period of time but batteries were nowhere near flat) as has been said by others the best thing to do is all LED lighting and a soLar panel. We Never ever use EHU during the summer. The cost of overnight EHU far outweighs the saving in gas for the fridge (especially with Gaslow)

Different story in the winter though, think 1 night without EHU or driving a good many miles.


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## weldted (May 1, 2005)

*Batteries*

Ideally if fitting two batteries they should be of the same age and capacity otherwise the older/weaker one will pull the new one down. The batteries should be connected negative to negative and positive to positive, with a fuse between the positives. To run any kind of inverter will soon pull your batteries down, by the time you taken into account the efficiency loss of the inverter, voltage drop from the cables, you are looking at 
26/28 amps at 12volt d.c. To give you 1amp 240 a.c.
As a rule of thumb if you have two good 100 amp batteries that will give you a max usable 100 amps, care should be taken not to run the batteries low as this will shorten the life of them.
We run our inverter from the engine battery as this type of battery is designed for heavy current draw/ charge. Leisure batteries are designed for small amount of current over longer periods around 10% of their capacity draw/ charge. By using the engine battery, if I need the microwave or vac on for more than.say 10 mins I just run the engine, obviously with consideration for other campers. We have 300 watts of solar panels, which copes with our requirements in the U.K. from around May to Sept, and Southern Spain Portugal most of the year.
Good luck


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## listerdiesel (Aug 3, 2012)

*Re: Batteries*



weldted said:


> Leisure batteries are designed for small amount of current over longer periods around 10% of their capacity draw/ charge.


Sorry, that isn't true.

Leisure batteries can produce high discharge currents just as readily as a starter battery, and for most users they are virtually interchangeable.

Any restriction on discharge current is determined by the internal impedance of the battery and the capacity. Given that both starter and leisure batteries are virtually one and the same these days, there's not a lot to choose between them.

Peter


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## TheWoodentops (Jul 10, 2013)

Many thanks for all your advice.
I think a solar panel, perhaps 150w is the way to go, which should go a long way to keeping the batteries ok.
I understand there are 3 types. Is there a lot of difference between them apart from the price.


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## TheWoodentops (Jul 10, 2013)

Many thanks for all your advice.
I think a solar panel, perhaps 150w is the way to go, which should go a long way to keeping the batteries ok.
I understand there are 3 types. Is there a lot of difference between them apart from the price.


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## andrewball1000 (Oct 16, 2009)

you may find this thread useful to read http://www.motorhomefacts.com/ftopict-132439-independent.html+ehu


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## listerdiesel (Aug 3, 2012)

TheWoodentops said:


> Many thanks for all your advice.
> I think a solar panel, perhaps 150w is the way to go, which should go a long way to keeping the batteries ok.
> I understand there are 3 types. Is there a lot of difference between them apart from the price.


Monocrystalline is the one to go for, most popular and cheaper.

If you are going to buy a high-power panel, make sure it is 36 cell NOT 72 cell. A lot of 72 cell panels are on the market right now, but these will not work with a 12V MPPT controller as the input voltage to the controller is too high.

This is a typical 36-cell (count the cells on the panel):

http://www.ebay.co.uk/itm/310817413484

This is the best of the MPPT controllers:

http://www.ebay.co.uk/itm/130549038710

Peter


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## weldted (May 1, 2005)

*Batteries*

Quote from the handbook, "In both construction and operation requirements vehicle and leisure batteries are different....contrary to some of the claims made a starter battery performs poorly as a leisure battery and conversely. There is no such thing as a dual purpose battery. A vehicle starter battery is designed to provide an initial burst of power in order to start the engine. By contrast a leisure battery provides a steady flow over an extended period..

taken from page 88 of the Motorcaravan handbook (a great source of info)


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