Smallest panel to run a 32L Fridge? Or add another panel to my camper setup/

[mudski]

Yep, sure will.

There are a few different options depending on how an individual setup is wired and what solar regs, DC/DC devices are in use etc. but simplest way is just hook the sucker up in parallel.

Keep the lead as short as is convenient say 3 to 4 metres max and use reasonable gauge cable say 12 to 10 gauge and you won't have much voltage drop at all over the extra distance to the vehicle aux.

Great... My camper has the bcdc in there for the two batteries...
One more for you. The panels I borrowed from lucas30. His have the reg on the back. Say if I wanted to add his panels to my 180w setup for the extra help. Can I just clip his panels onto one of the batteries on my camper? Even though they are connected to my bcdc? If I can would it matter which battery?
Just trying to cover my bases here if need be.

[the evil twin]

Great... My camper has the bcdc in there for the two batteries...

Awesome, it gives you a few options on what to do in future but as this is a one off...

The panels I borrowed from lucas30. His have the reg on the back. Say if I wanted to add his panels to my 180w setup for the extra help. Can I just clip his panels onto one of the batteries on my camper? Even though they are connected to my bcdc?

No, you will end up with a situation of bucking power supplies.
Either the BCDC will confuse the Solar Reg or more likely the other way around as the Panel Reg probably has a higher open circuit voltage and the BCDC will just sulk and do nothing... but def one or the other

The panels I borrowed from lucas30. His have the reg on the back.

If that is the case (and Lucas doesn't mind) the most efficient way would be to disconnect the solar panel cable that feeds into the solar panel onboard reg and connect the panel output direct to the input of the BCDC so his panel is now in parallel with yours.
Sometimes most efficient isn't the easiest or best way tho.

Next best would be to leave his gear as is and hook his Solar panel regulated output to your vehicle Aux battery.
If it is a one off trip, the vehicle isn't moving much and the fridge is staying in the car I would probably do that
Mainly as you have a lot of Solar for your Camper (and large battery capacity) already

Hope all that makes sense

[mudski]

All makes sense thank you. When I get back I will get an extra single panel, get a BCDC1225 reg for the car to replace my SBI12 ( I think it can be done) so then I have the option of using the single panel for the car or add to the trailer. But if I were to run a lead from the car to the trailer for triple batts I'd have to have a switch of some sort to shut off the reg in the car wouldn't I?

[the evil twin]

All makes sense thank you. When I get back I will get an extra single panel, get a BCDC1225 reg for the car to replace my SBI12 ( I think it can be done) so then I have the option of using the single panel for the car or add to the trailer. But if I were to run a lead from the car to the trailer for triple batts I'd have to have a switch of some sort to shut off the reg in the car wouldn't I?

If the existing aux is under the bonnet I would consider staying with the SBI12 and a seperate cheapish Solar Reg attached to the Aux that you plug the panel into.
Just means you have a high current path back to the Cranker for winching, jump starting etc. and much cheaper than buying a second BCDC
BUT
From what I can glean I think your camping profile may mean that a second BCDC is more appealing to you

If you put a second BCDC in the car then wire it as per figure 12.5 in the install manual.

This will mean that the car BCDC is not powered if the Ign is off and therefore;

Option A - Panel plugged into Car BCDC and Car NOT connected to camper.
The Car BCDC will run on Solar to charge the Aux unless Ign on and then the Alternator takkes over.

Option B - Panel plugged into the Camper array at the Camper BCDC and Car connected to Camper and Car ign off.
The Camper will have the larger Solar Array capacity available and the Camper BCDC will charge the Camper Battery Bank and the Car Aux all as one (the CAR BCDC will not be powered)

[megatexture]

You've got me intrigued here. Do you have the lead with the anderson plug directly to the aux battery in the car then connect to one of the two batts in the camper? Two weeks camping with NO mains power I just want to be prepared... Dib, Dib, Dib.

I plug into the Anderson on the rear bar and then to a plug I've got on the trailer going straight to the batteries for this purpose.

[mudski]

If the existing aux is under the bonnet I would consider staying with the SBI12 and a seperate cheapish Solar Reg attached to the Aux that you plug the panel into.
Just means you have a high current path back to the Cranker for winching, jump starting etc. and much cheaper than buying a second BCDC
BUT
From what I can glean I think your camping profile may mean that a second BCDC is more appealing to you

If you put a second BCDC in the car then wire it as per figure 12.5 in the install manual.

This will mean that the car BCDC is not powered if the Ign is off and therefore;

Option A - Panel plugged into Car BCDC and Car NOT connected to camper.
The Car BCDC will run on Solar to charge the Aux unless Ign on and then the Alternator takkes over.

Option B - Panel plugged into the Camper array at the Camper BCDC and Car connected to Camper and Car ign off.
The Camper will have the larger Solar Array capacity available and the Camper BCDC will charge the Camper Battery Bank and the Car Aux all as one (the CAR BCDC will not be powered)

If I don't really need the BCDC and can get away with a cheap'ish reg I would do that. But I need to sit down and work it out properly first.
Ideally. I'd like to be able to do this...
Be able to independantly connect a smaller panel to the aux in the car when need be. And. Be able to run the aux battery as a third battery with the two camper batteries.
My Aux is a deep cycle too, and the camper batts are the Gel type. Would this matter for charging purposes if all conected?

I plug into the Anderson on the rear bar and then to a plug I've got on the trailer going straight to the batteries for this purpose.

I have the same but my anderson on the rear of the car is to charge the batts whilst driving and also the panels plug into it.

[megatexture]

The Anderson plug on my rear bar is straight to the aux batt on the gu

I have 3 Anderson plugs on the front of my camper,

one that connects to car for charging while driving via ctek on the camper.
One that's connects 2 the ctek for solar pannels (I also have one on the back depending on what way the campers facing)
One that goes straight to the batteries for linking the gu aux battery

[the evil twin]

If I don't really need the BCDC and can get away with a cheap'ish reg I would do that. But I need to sit down and work it out properly first.
Ideally. I'd like to be able to do this...
Be able to independantly connect a smaller panel to the aux in the car when need be. And. Be able to run the aux battery as a third battery with the two camper batteries.
My Aux is a deep cycle too, and the camper batts are the Gel type. Would this matter for charging purposes if all conected?

You can do solar part easily by putting a Solar Reg across the Aux Battery.

The "third battery" becomes and issue because your Camper batteries are being charged by a BCDC.
For the Aux to become a third battery it will need to be downstream of the BCDC.
You will need to run a cable from the BCDC output back to the vehicle Anderson plug.
(the third cable that Mega refers to in his post)

The 'Gel' or 'not Gel' battery is not a problem.

[mudski]

Thanks guys you have given me inspiration to spend more moolah.
Looks like mega is a ideas man too with his trailer.

[the evil twin]

Thanks guys you have given me inspiration to spend more moolah.

I'd hold off for a while... you haven't got the Invoice for my Consultancy Fees yet.