Leisure Battery, Split Charge or Towing Electrics?

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LandyMan

LandyMan

Well-Known Member
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somewhere in the UK
Hi people of Landy world,

I am going to be fitting a leisure battery in my boot to run some lights and a fridge.

Do I need to install a relay charging system if I have already got towing electrics?

I have 2 electric plugs next to my towbar, 1 for lights and I assume the other is for caravan electrics (ie to charge the caravan leisure batteries while on the move).

If i can use the towing electrics, does anyone know what I need to do?

Thanks
 
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I would use a relay to isolate the leisure battery from the car battery when the engine is not running or you could flatten both batteries.
Plenty of info about split charging on Google.
 
NDavies said:
Yes I have got the electrics, but I am thinking about removing my towbar as I never use it.

How can I connect a relay? have you ever done this before?
Click to expand...

If you have double electrics the split charge relay will probarbly be there some where. Check behind the panels in the boot. The auxiliary 12s socket (Grey cover) should be wired as the picture below. Test the no 2 pin (should be blue wire). This should become live when the engine is running.
watling-wd_12s_selfswitch.jpg


Find where the wire goes and fit a 12v cig lighter plug in the boot with an inline 10a fuse. Thats what I did.

You mention a fridge. There is a wire dedicated to this for a caravan and will be powered up when the car is running (no 6 red in drawing).
 
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Pin 2 might not be connected as the standard changed around 1999. If that's the case, you should use pin 4 to charge the battery, via a relay switched by pin 6.
 
Yes, I did the same thing. I just made up a plug wired into Pin 2 (+12v battery charge) and Pin 3 earth (white socket). Ran it into the read compartment (the door seal didn't damage the lead) onto the battery.
 
Hi guys, it's been a while, hope you're all ok?

So, I have found the blue wire from the 12s socket, it is already connected to a relay before it goes to the plug, so I'm going to just use that to charge the leisure battery.

Thanks, i'll let you know how it goes.
 
One thing I'd do when you first do this - put an extra 15/20A fuse in the line near the battery.
Or figure out a switched line for your relay that isn't on when cranking.

If your leisure battery can produce more current than your starting battery (when it's getting tired) current will flow back up the line to the starter and damage wiring. Better to have a fuse, just in case. If the fuse pops when you crank, the starter is pulling current out of the leisure batt... if that makes sense?
 
NDavies said:
yes that makes sense, but it's just the wire to charge a leisure battery in a caravan, so I would think that it's all quite safe to use?
Click to expand...

Sorry, have I misunderstood, is this being fitted inside the freelander or a caravan? (And is your relay a voltage sensing one, or just a standard relay?)
 
it's being fitted inside the freelander, I am using the blue wire from the 12s socket that would normally charge a battery inside a caravan. I;m not sure what type of relay it is, I assume its the relay that would come with a 12s kit
 
NDavies said:
it's being fitted inside the freelander, I am using the blue wire from the 12s socket that would normally charge a battery inside a caravan. I;m not sure what type of relay it is, I assume its the relay that would come with a 12s kit
Click to expand...

For safety, I'd put an in line 20 amp fuse near the leasure battery + terminal. It's far too easy for a wire to short to ground, starting a fire. I have an auxiliary battery in the second battery box on my Discovery 3. This is charged via a voltage sensing relay from the main battery. There is an in line 20 amp fuse near both battery + terminals. This is to protect the wiring from both ends. You can never be to careful with high current power sources. ;)
 
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I was testing over the weekend, the relay IS a voltage sensing relay (sweet!), I will defo put a few fuses in and around the battery :)

I will fit the battery this weekend and let you know how it goes.
 
Just out of interest (and because it just occurred to me) - this is a caravan style battery, right with a vent on it?

I've seen what happens when someone tries to charge a yuassa sealed lead acid battery from an alternator...
 
Yeah, that's vented, will be fine :)

It's the sealed ones you have to watch, an alternator causes their burst disk to pop normally as they're supposed to be regulated when charged!
 
B34R said:
Yeah, that's vented, will be fine :)

It's the sealed ones you have to watch, an alternator causes their burst disk to pop normally as they're supposed to be regulated when charged!
Click to expand...

A Sealed Lead Acid (SLA) battery can be charged quite safely in the car provided the correct procedure is followed. ;)
They need to be charged via some kind of current limiter to prevent gassing, particularly when they are discharged. The charge current should be kept at a maximum of 1/10th the battery's Ah rating or 0.1 C where C is the Ah figure. This can be with a complex charge controller if you are willing to spend on it. Or if you would rather spend the money on a bigger battery, a simple 12 Volt light bulb works well. Choose a bulb that has the current flow of just under 0.1 C. This could be a tail light, brake light or headlight bulb. Whatever keeps the maximum current flow under spec. Charging at 0.1 C will charge a discharged SLA in 14 to 16 hours.
In my D3 I have a 36 Ah SLA changed via a voltage sensing relay and 2 X 21 Watt brake lamp bulbs in parallel. This gives a charge current of 3.6 Amps which seems to be fine for such a large SLA battery.
I've not had any issues for the 6 months I've had this system up and running.
 
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