Leisure battery fitting advice

[frogdude]

Hi all

I'm putting a leisure battery in the back of my '78 Bedford CF autosleeper, and i'm calling on the great wise oracle that is you guys.

Not being too great with electrickery, i'm opting for a simple set up. The leisure batt is going under the seats in the back, with the live connected to the live of the vehicle batt using an old jump lead (should be heavy duty enough?) I'll cut the croc clamps off and use proper terminals. The vehicle batt is located on the step inside the passenger door and it's easy to get to, so i'm putting an isolation switch on the terminal there (obviously only connected to the leisure battery cable) so it wont drain the main batt when i'm using the leisure one. It'll simply be a case of flicking the switch (after the van's been started) when i need to charge it, and swtching off again once stopped. I'm not touching the fuse box, as i only want to connect a 12V socket to the leisure battery to power a 12V TV and recharge phones etc.

So here's the questions. Should i earth the negative on the leisure battery to the vehicle body or connect it to the neg on the main one?
The length of cable between the batteries will be about 4 feet, is this too much?
Is the plan with the switch a good idea? I'm thinking of using one of those terminals with a knob, think they're called dis-car-nect.
Can anyone think of anything i should know, or any reason this is a daft idea?

Thank you o wise ones!

Rich

 

[Deleted member 207]

It will work fine until you forget to isolate the starting battery and flatten it along with the leisure battery

Simplest wiring is to have a solenoid (best use 80amp or more) that turns power off to the leisure battery as soon as the engine stops running. You can use the "signal" terminal from the alternator (same wire that turns the red alternator lamp off on the dash) to control the solenoid.

Maybe do a weblookup on "leisure battery wiring diagram", I'm sure there are pics or schematics available as well.

 

[frogdude]

I've had a look, but i think it's a bit beyond my non-existant auto electrical skills. I've just been looking at voltage sensing self switching relays on Ebay. Do you know anything about these?

 

[paulamy]

we fit them to our campers there easy just a wire from the vehicle battery to the relay and then join up whatever you need as per the diagram they supply.only connects when the vehicle runs and the charge rate rises.

 

[chopper]

i do exactly the same as you said in the first post
and all is fine
ive had 4 campers done that way and never forgot to turn it off while parked yet
cheap and simple
but there always a chance i forget lol

 

[AndyC]

Should i earth the negative on the leisure battery to the vehicle body or connect it to the neg on the main one?

You could do either, but it would be better to connect negative to negative.

The length of cable between the batteries will be about 4 feet, is this too much?

If you are using jump start cables it's fine

Is the plan with the switch a good idea? I'm thinking of using one of those terminals with a knob, think they're called dis-car-nect.

It's nice and simple, but not foolproof! There is always the chance that you'll forget to isolate it one day...

AndyC

 

[Wez]

Hi,

I've just fitted a split charging relay to my van.
It may look worrying but it's really simple - that hardest part is running the wires, so if you can hold a drill and a screwdriver - you can install a split charge relay.

I got the relay, relay holder and connectors from maplin electronics (£5ish, 30amp - 4 pin - 12v)
The pin numpers are marked on the relay so you cant go wrong.

The negative of your camper battery goes to vehicle body (earth)
Pin 85 on the relay also goes to earth.
Pin 86 goes to a 'switched ingnition-on' live, this could be coming from the wire on your alternator that goes to the charge light on your dsahboard, its easy to find - the wire is the thin cable on a single connector on the back of your alternator, or you could even wire it to something else that is only 'live' when the ignition is on (radio for example)
The other two pins are connected to the live terminals of the batteries.
Pin 30 to engine battery, pin 87 to leisure battery.

It really is simple - honest, 4 wires!

Then as soon as the engine is started - your leisure battery is charging, as soon as you turn the ignition off - it stops charging and the leisure battery is completely disconnected from your engine battery, so no chance of flattening it.

 

[Chrissy]

Really Useful + Curious thing

Hi Wez
Thanks for that I copied and pasted into word and hubby can set this up.

Curious thing though - as far as I know, we don't have anything charging our leisure battery and we do only use it for lights and the sink water pump but we have used it loads of times and the charge doesn't seem to go. Am I talking a load of rubbish and being a liar to-boot (unwittingly of course) or can this be the case?
Chrissy

 

[frogdude]

That's fantastic, thank you so much for all the advice, i've got a much clearer understanding now. I feel ready to at least make a decision!

 

[dogseal]

Hi Wez
Thanks for that I copied and pasted into word and hubby can set this up.

Curious thing though - as far as I know, we don't have anything charging our leisure battery and we do only use it for lights and the sink water pump but we have used it loads of times and the charge doesn't seem to go. Am I talking a load of rubbish and being a liar to-boot (unwittingly of course) or can this be the case?
Chrissy

Are the lights connected separately from your leisure battery? The two circuits should be indepentant from each other..IE someone may have wired the lights through the cab interior light which is always live. On the other hand, just using the leisure battery for Lighting and pump would last a few days depending on your setup.

I've got a 85 ah leisure battery on mine under the bonnet & it lasted 3 days with the tv on for a couple of hours on a night, a few 8 amp lights on for the same time. Then I bought a 12v inverter to charge our netbook..hooked it up..it charged the netbook but killed the battery untill I drove home.

Most folks have bigger batteries than ours, but I've had 4 years out of this one!

Take care Chrissy...The folks on the self build site would answer your question to the nth degree. ( Qriz B ?)

dogseal

 

[Deleted member 3011]

It really is simple - honest, 4 wires!

10 Amp fuses seem a bit light-on. Fine if both batteries are close to fully charged, but if the leisure battery ever gets flat, the current may be high enough to blow the fuse(s)

 

[Wez]

10 Amp fuses seem a bit light-on. Fine if both batteries are close to fully charged, but if the leisure battery ever gets flat, the current may be high enough to blow the fuse(s)

I'll be honest - i havent put any fuses inline with the battery yet anyway, hence not mentioning them in my little description. Shall do soon though once my van is all finished and everything wired up and finalised.

Hope it helps a few folk

 

[Hirohito]

Split Charge Relay Wiring

Hi Wez, I have the relay you described & also bought the alternative German model from Halfords N73AU. Now I have no problem understanding boths systems but what foxes me, is how do you connect your wires to your relay eg:-you show your lead going to No 30 (with fuse). now this is a hefty wire so how do you connect? ditto your wire from leisure battery to No 87..Can you advise....Regards.ps.,I would think that 20 amps fuses would be more appropriate.
Anybody out there who can answers that simple question ie., how do you connect the massive wires to the small relay stubs ?