Wiring up a 3 way fridge to existing relay?

[welshrussell]

I have now acquired an Electrolux 3 way fridge (thank you Alan ).

For the moment running it on gas is not an option (personal preference) and I am quite happy for it to be plugged into the 240v system when I am at a campsite.

However, I want it to be kept cool whilst driving to the site, so want to wire it up to my leisure battery.

I already have the van wired up to the same spec as a drawing that it appears quite a lot on the forum (that's where I found it ). It is the relay one with 30, 85, 86 and 87 on it which charges from the starter battery whilst driving.

My question is about the two 12volt cables coming from the fridge:

Can I just wire these to the leisure battery with an inline fuse or should it go through the relay somehow

I'm hoping this will be a relatively straightforward job

[ake]

If you wire it straight to the battery it will work ok till the battery is flat, the draw is pretty high on them

[welshrussell]

If you wire it straight to the battery it will work ok till the battery is flat, the draw is pretty high on them

Thanks

I thought if it was wired to the leisure battery it would be getting a constant charge from the alternator as I drove along

Isn't that what the relay does and also prevents any power from the starter battery being drawn

[pippin]

It is usual for the relay to provide power to the fridge only when the engine is running.
In effect it is running from the engine battery which is being recharged by the alternator.

Better to use a separate relay from that which charges the secondary (leisure) battery otherwise you could end up draining the leisure battery.

These fridges take a not inconsiderable ten amps on 12V.
You do not want to introduce additional voltage drop into the leisure battery charging circuit.

Ensure the contents are well chilled before loading them into the fridge, even to the extent of putting a deep-frozen bottle of milk in - it will keep everything else cool and will probably have thawed out by the time you need it!

Do remember to cool the fridge right down on 240V before leaving home as they are not very efficient on 12V.

[welshrussell]

Cheers Pippin - very helpful

The question is now - what wires where

The problem is I just can't see/figure out what wires should connect where.

Is it best just to ignore the leisure battery wiring setup I've got and wire in a new loom to have the fridge charging whilst driving

Hope someone knows what I'm talking about - sorry if it's a bit misleading

[ake]

Cheers Pippin - very helpful

The question is now - what wires where

The problem is I just can't see/figure out what wires should connect where.

Is it best just to ignore the leisure battery wiring setup I've got and wire in a new loom to have the fridge charging whilst driving :?

Hope someone knows what I'm talking about - sorry if it's a bit misleading

Yes

[welshrussell]

So, does this mean.....

Buying a new relay and wiring it to the leisure battery - earth - and alternator again, like the first relay set up

[pippin]

Yes and No!

Yes you do need to buy a second relay.

No, don't involve the secondary battery.

You need to connect the contacts of the new relay direct to the engine battery positive (via a fuse) and thence direct to your fridge. You need to use fairly heavy cable.

Earth the negative of the fridge near the fridge to the chassis.

The relay coil needs to be connected either to the alternator signal wire or even better to an ignition on controlled 12V.

[welshrussell]

Cheers Pippin - now it's starting to make sense (a bit)

Sorry for being dense - auto electrics are definately a weak point for me.

This time I think I've got it

1) Pos cable from starter battery straight to terminal 30 on relay (with say 10 or 15amp in line fuse).

2) Connect fridges pos wire to relay terminal 87

3) Connect wire from alternator signal wire to relay terminal 86

4) Earth fridges neg wire to van chassis

God - I can't beleive this

There's only 2 Fecking wires coming from the fridge

[pippin]

The fridge 12V only needs two wires, pos (to relay contact) and neg (to chassis)!

You will also need to connect the other end of the relay coil to something.

If you are connecting one end to an IGN ON circuit then the other end needs to go down to chassis.

If you are using the alternator signal point then I am not too sure.

It could be that the alternator signal point might not take too kindly to a second relay being connected to it. Sometimes it causes the "battery charge" light to glow all the time.

I hope someone else will be along to clarify that aspect.

[Luke]

so if the fridge see's 12v does it automatically switch to that

i think i'd wire it so the realy for the switch pulls in when the ignition is on - as you never leave that on unless your starting/driving

mabe also wire in a switch to the feed to the relay so you can switch off the fridge - just while starting in cases when you need all the battery power available

[pippin]

Yup! Found it.

http://www.motts.org/SPLIT%20CHARGING%20SYSTEM.htm

[pippin]

Trouble is you would forget to switch the fridge back on!

The fridge is not that intelligent!
The 12V connections go direct to the 12V heating coil.
The 240V connections go direct to the 240V heating coil.

Theoretically you could run both at once if you start the engine while still connected up to mains.
However your real problem would be pulling the side off your van if you drive away still connected.........!!

[Luke]

how about.............. a timed relay (say 10-15secs) so it pulls in once the engines started but while your cranking it doesnt put any extra drain on the battery

[welshrussell]

Cheers for this guys - very helpful of you

I'm understanding a bit more, but I need to read Pippins link a couple of times (great drawings thought!).

I think the only bit I'm confused on now is where to connect to the alternator bit.

I'm not really wanting switches etc to turn the fridge to 12volts as there is a button for that on the fridge and as soon as I get to a site, the first job I do is to plug in the 240 hook up, so I would remember to switch the fridge to 240v then.

I take it, it's not a good idea to wire up a second relay to the alternator light then