12V compressor fridge wiring

Puddlejumper

Guest
Good morning all,
Our old RM212 fridge decided to die a few weeks ago and after much searching around we decided to replace it with a Waeco 12V compressor fridge. I've currently got it wired up to run from the habitation batteries but want to also wire it so it's running while the engine is running. Can anyone tell me how to do this, or better still has anyone got a wiring diagram I could use?
My worry is that as I've taken the habitation feed from the fuse box if I then wire in the engine battery then I will make the habitation fuse box live while I'm travelling. I don't even know if this is a good thing or a bad thing:D
My initial thoughts were to run through a voltage sensing relay or even just a on-off-on switch (of course that means I gave to remember to switch it on/off every time I drive/park)
Hope I've described my issue well enough for folk to understand and I'm looking forward to your helpful replies
Doug
 
Good to see you over here Doug....

I just wired our Waeco to the leisure batteries via a suitable fuse and let the Durite VSR and solar look after it.
Been like that for 2 odd years now running none stop (we tend to be away most weekends)
Only time I've ever hooked up to charge the batteries was over the winter when we didn't bother going away for 3 or 4 weekends due to the abysmal weather.
 
mistericeman said:
Good to see you over here Doug....

I just wired our Waeco to the leisure batteries via a suitable fuse and let the Durite VSR and solar look after it.
Been like that for 2 odd years now running none stop (we tend to be away most weekends)
Only time I've ever hooked up to charge the batteries was over the winter when we didn't bother going away for 3 or 4 weekends due to the abysmal weather.
Click to expand...

Bloody hell mate, you get everywhere :dance::dance:
 
hairydog said:
The reason that the habitation electrics go off when the ignition goes on is a silly one: if the wiring was left on with the ignition, it would all have to pass type approval certification, which would be needed separately for each variant of each model of motorhome.
By making it go off, the makers save a lot of hassle and expense.
Once you have bought the vehicle, there is no reason at all to leave it like that, and almost everyone changes it so the habitation electrics work all the time. Including your fridge.
Click to expand...

So in essence just wire the original 12V supply from the engine circuit into the connection to the fridge along with the habitation supply and off we go??
Simples:idea:
Thanks guys
 
Presuming that there is already a means to charge the habitation battery whilst the engine is running, I would leave well alone and have the fridge permanently connected to the habitation battery.

If you have solar as well, which you are likely to need with a compressor fridge, you will be all set.
 
POI Admin said:
Presuming that there is already a means to charge the habitation battery whilst the engine is running, I would leave well alone and have the fridge permanently connected to the habitation battery.

If you have solar as well, which you are likely to need with a compressor fridge, you will be all set.
Click to expand...

Yep, we've got 240W of solar & 330ah of battery.

Thanks for all the advice guys, much appreciated
 
Puddlejumper said:
Good morning all,
Our old RM212 fridge decided to die a few weeks ago and after much searching around we decided to replace it with a Waeco 12V compressor fridge. I've currently got it wired up to run from the habitation batteries but want to also wire it so it's running while the engine is running. Can anyone tell me how to do this, or better still has anyone got a wiring diagram I could use?
My worry is that as I've taken the habitation feed from the fuse box if I then wire in the engine battery then I will make the habitation fuse box live while I'm travelling. I don't even know if this is a good thing or a bad thing:D
My initial thoughts were to run through a voltage sensing relay or even just a on-off-on switch (of course that means I gave to remember to switch it on/off every time I drive/park)
Hope I've described my issue well enough for folk to understand and I'm looking forward to your helpful replies
Doug
Click to expand...

When connected to les batterys it will also be connected to main starting battery once you start the engine,so leave as is with a fuse in line.
 
hairydog said:
I still don't feel this is sorted. Don't change any of the fridge wiring. Leave it running from the habitation power.

Find the relay that switches off habitation power when the engine is running and stop it doing that. Sorted!.

I've not had a motorhome with this stupid arrangement, so I'm not clear how they do it, but I expect it is tied in with the SCR or at least the D+ cable.
Click to expand...

Pretty sure it will be the D+ signal as you surmise.
I installed the Sargent EC155 PDU in my VW T5 conversion and if I would have installed it as 'dictated' would have had this 'Habitation Electrics off when Driving' feature - which makes sense for a Caravan but not a Motorhome. I didn't wire up the vehicle charging side of it as used a better solution so never had to bother with finding that relay to disable - but would have if need be!

On the Fridge side, if the fridge comes on and off depending on a D+ controlled relay or similar, I would also not be surprised if it has not been installed optimally in terms of cable gauge either so would definately investigate that further as well anyway. A 12V Waeco Compressor Fridge needs 4mm cable minimum and if the cable run is a bit convoluted, raise to 6mm; also best to connect direct to the battery (via a fuse of course) rather then battery management systems, relays or switches.
 
Haven't really looked at it for a few days as we've been away. Had a few days off grid and solar managed to keep us well topped up battery wise.
I probably need to try and better explain what I've done wiring wise.

Originally, with 3 way fridge, 12v supply only worked while engine was running. Once it was replaced with 12v compressor fridge I took a 12v feed from the habitation fuse box (originally it was a cig lighter type accessory socket) so the fridge is always running when 12v is switched on rather than having another switch to worry about. The 12v feed from engine has now basically just been isolated. I know if I wire in the vehicle battery feed to the fridge it will make the whole of the leisure side live if that makes sense? The question is will that cause a problem or do I need to either:

a) add a switch into the LB fridge feed

or

b) wire the fridge through a relay so while engine is running the fridge is running from that source but once engine is stopped fridge is running from habitation batteries

I hope that makes sense and thanks to everyone for their input up to now
 
We seem to be in Groundhog Day territory here!

POI Admin said:
Presuming that there is already a means to charge the habitation battery whilst the engine is running, I would leave well alone and have the fridge permanently connected to the habitation battery.

If you have solar as well, which you are likely to need with a compressor fridge, you will be all set.
Click to expand...

QED
 
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