# Can you charge 2 leisure batteries off the alternator?



## davewoody (Jun 22, 2009)

Just wondered if you could charge 2 leisure batteries off the alternator.


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## Jean-Luc (Jul 21, 2005)

The simple answer is yes.


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## GerryD (Sep 20, 2007)

Provided the batteries are correctly installed, they will share the output from the alternator.
Gerry


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## greenasthegrass (Oct 27, 2007)

Definitely my dad put me an extra one in and we just switch over when not on hook up and join them together when we set off - don't ask me how he did it though am a girl and its a boy job.

Greenie


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## citroennut (May 16, 2005)

i'm running 4x leisure batteries though have an uprated alternator.
simon


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## CliveMott (Mar 10, 2008)

You will get more out of two leisure batteries by connecting them permanently in parallel than you will by using one and then using the other with some form of change over.

I have some unused 90 amp Bosch alternators languishing in my garage if anybody fancies having a play to fit a second alternator. For those without cab air con the space for the aircon pump could be a second alternator position.

C.

www.motts.org


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## DABurleigh (May 9, 2005)

"You will get more out of two leisure batteries by connecting them permanently in parallel than you will by using one and then using the other with some form of change over."

That's the upside of Peukert. There's a lot to be said for plate area.

Dave


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## bob44 (Mar 9, 2006)

Hi davewoody,

Using Two Leisure Batteries - How I Did It.

Three years ago my single 65 amp hour leisure battery needed replacing so, after research, I bought two identical elcosol 100 ah leisure batteries, and fitted the second one (Battery No. 2) under the Fiat Ducato cab passenger seat box. (The other went under the Drivers seat box, replacing the original as Battery No.1)

Suitably fused, these are connected via a marine quality leisure battery change-over switch, similar to this:

http://www.eveshamboatcare.co.uk/battery-change-over-switch-p-211.html

This switch is handily mounted at the left side panel of the drivers seat box.

The switch positions are:

OFF - Whenever vehicle is unoccupied - Total isolation of both leisure batteries.

BOTH - For charging whilst travelling, or on EHU (or v occasionally on my rarely used Kipor Generator) Over time this ensures fairly equal but separate loading of each battery. The chosen 'Duty' battery then remains in use until the level at a voltmeter drops to around 12.2v; then the other battery is selected and monitored carefully too, avoid both becoming flat.

For the 12v monitoring I have wired an additional set of a cheap Voltmeter connectors into a cigarette lighter type plug to provide for a leisure-battery-in-use-check at any 12v leisure socket. (When plugged into the dashboard cigarette lighter socket this meter will also read the separate Engine BatteryVoltage, too.)

My above 'Operating Procedure' may not be as electrically efficient as Clive Mott and Dave Burleighs wise advice to use batteries connected in parallel/ Plate area.

However (for us) it does have the advantage of knowing that there should always be a 'spare/alternative' leisure power source available.

Hope that our experience is of some help to you.

Bob L

PS We are light and careful users of 12v when not on EHU (never carry a TV either) 
but I promise to try out Clive/Daves advice myself sometime and select BOTH on site as a monitored trial.


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## DABurleigh (May 9, 2005)

Bob,

Whether it makes any difference depends on your maximum discharge currents and how usual they are. In my own case I can have TV, satellite controller and dish powered, then the diesel heater in glow-plug current zapping mode, along with lighting :-(

Dave


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## welshtust (Jun 9, 2008)

In the van we run two in parallel, but matching batteries. both 95AH
We I had the Limo, which had LCD Lighting, Two TV's Amps and Bar lights running, the Americans used a second alternator, this worked well.
Plus running two air con units.
Really think it up to you, will you use the 12v while on the move, we have the TV on for the children and Diesel heating in the winter.
That's when a 2nd alternator is great as it can run the electrics and charge.


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