Thetford N3000 Fridge wiring.. "help"

Darcar

Well-Known Member
Joined
May 12, 2016
Location
East Devon
#1
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Hi all I'v installed my fridge & in the process of wiring in my 12 volt system..
I've run a 12v + supply & a negative - wire from the control panel. To the back of the fridge.....
when looking at the plug from the fridge it's got 5 wires going into it!

Now I think that the 2 thick wires (white and red ) are the power in & earth. But I don't understand what the other 3 wires are!
There's a couple which are purple and black which are called " low current supply " ?
The last wire is orange & is D+ signal

I've put up a picture of the relevant install manual but I still don't get it?
Thanks Darren
 

david.c.hall

Active Member
Joined
May 16, 2016
Location
Irnham, South Lincolnshire
#2
The purple and black are the permanent power supply supply from the leisure battery to run the electronics.
The orange is from the D+ to switch the 12v power on to run the fridge to run it off the engine/alternator once the engine is running.
They are a separate from the others (the white and red) as they go to the vehicle battery not the leisure battery.
Hope this helps
David
 

Darcar

Well-Known Member
Joined
May 12, 2016
Location
East Devon
#3
The purple and black are the permanent power supply supply from the leisure battery to run the electronics.
The orange is from the D+ to switch the 12v power on to run the fridge to run it off the engine/alternator once the engine is running.
They are a separate from the others (the white and red) as they go to the vehicle battery not the leisure battery.
Hope this helps
David
Thank you very much David.

Once it's explained like this, I understand it.
Well ALMOST...
so I run a couple of cables, the white - and red + to the van batteries, which are 24v but I've got a dropper which gives me 12v for the radio, so I can pick up the power there? This runs the fridge on 12 v when the engine is running. ( I get this bit now)

The D+ (Orange) switches it on when the engine is running . But Where dose the D+ wire go? to pick up the signal for when the engine is running?
Thanks again Darren.
 

david.c.hall

Active Member
Joined
May 16, 2016
Location
Irnham, South Lincolnshire
#4
Ahh!! 24v!!
Right well first of all when on 12v it is rated at 140 Watts. So around 12 amps
Does your 24v to 12v dropper have that amount of spare capacity?:(
The D+ is the same connection that you would use for a split charge relay.
So if you use this system ( and not a voltage controlled system) then you can piggy back off of that, PROBABLY:(
Not sure how 24 to 12 works??
It comes from the control wire on the alternator and if you need to pick that up you may need to take that to a 24v relay and then use the relay to switch 12v on.
Never played with 24v vehicle so perhaps someone who has can be of more help there.
Hope this hasn't muddied the waters too much?
David
 

Darcar

Well-Known Member
Joined
May 12, 2016
Location
East Devon
#5
Thanks again. David,

I've got a sterling E1180 b2b charger which is 45amp 24v to 12v which will charge my leisure batteries. This switches on at 26 volts.

Do you think I could simply wire the fridge directly to the leisure batteries ( 12volt ) and the switch ( orange D+ ) to the 12v out from the b2b charger?

This should start charging my leisure batteries when the van batteries get to 26 volts. & would only switch the fridge to 12v dc when the alternator / engine is working.

On another electrical point, the fridge installation says I should use a wire of 10 AWG. & a 30Amp fuse but what is AWG.?

Thanks for taking the time with your answers, I'm out of my comfort zone with electrics....
Darren..
 
D

Deleted member

Guest
#6
AWG stands for American wire gauge - google should tell you all details. Geoff.
 

david.c.hall

Active Member
Joined
May 16, 2016
Location
Irnham, South Lincolnshire
#7
Hi Darren
10 AWG (American Wire Gauge) is 5.26 mm2. So 6 mm cable.
I can't find a wiring diagram for the E1180.
Bit concerned that if you just connect to 12v out you may get feedback from the leisure battery, and finish up flattening the leisure battery.
David
 

Darcar

Well-Known Member
Joined
May 12, 2016
Location
East Devon
#8
Thanks again.
That's a very good point, I'd have never thought of the power feeding back..
so maybe if I put in a switch, I know I'll have to remember to switch it but I might stop the leisure batteries going flat.
Darren..
 

david.c.hall

Active Member
Joined
May 16, 2016
Location
Irnham, South Lincolnshire
#9
I would prefer the idea of a slave relay if you can find the D+
You could wire D+ to 24v relay to -ve and then connect 12v to the contacts and on to the fridge control wire.
I would inevitably forget the switch.
David
 

Grapework

New Member
Joined
Jun 18, 2017
Location
Middle England!
#10
I've been thinking about the same problem for our Vario. You don't just need a 24V relay, you need a voltage sensing relay that switches on at +26V, but then you would also need another relay with 24v coil to switch the 12v to the fridge D+. Or you could do the whole connection for fridge with an E932 which is a 15A version of the E1180 you already have. This way leaves the E1180 charging the 12v batteries at up to 45A and the 24V alternator powering fridge at 12v while engine running. Hope that makes sense !
 
Joined
Sep 16, 2017
#11
I've been thinking about the same problem for our Vario. You don't just need a 24V relay, you need a voltage sensing relay that switches on at +26V, but then you would also need another relay with 24v coil to switch the 12v to the fridge D+. Or you could do the whole connection for fridge with an E932 which is a 15A version of the E1180 you already have. This way leaves the E1180 charging the 12v batteries at up to 45A and the 24V alternator powering fridge at 12v while engine running. Hope that makes sense !
Are you not risking the fridge wiring powering it with a battery charger. Their not very subtle
Would it not be better for the fridge electricals to power it either from the leisure batteries as already said with a regular 24v relay, switching the 12v in and out as the vehicle is running or not. So the fridge gets power when the vehicle is running. This would save the fridge from surges and still give it 12v without killing the leisure batteries as they would be getting charged by the vehicle at the same time. Once the cranking batteries were full, which if the charging system is healthy really should not take long.
Or use a regular automotive dropper, then you just use the stock vehicle wiring to power the fridge and your leisure batteries are left alone. Less overlap of systems.
 

Grapework

New Member
Joined
Jun 18, 2017
Location
Middle England!
#12
Good point, yes battery charger not subtle! I am going to use a company called Adverc. They do the 15A chargers and also a 15A convertor which they say is the same unit but with the output set to 12.4v and will be ok for use with electronics.
 

Johnboy55

New Member
Joined
Jul 12, 2018
#13
Just reading up on this and understand the red/white and black/purple bit.
I have bought a CTEK charger for my solar panel/alternator charging to two 120 amp leisure batteries.
How does this affect the D+ Orange cable if at all?
 
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