Change 3-way-fridge to 12v compressor (wiring) + monitoring

Hello there,

I have an old 1987 Citroen C25 Atlanta Camper, which has been beautifully restored to its original state. The previous owner added 2 185 WP solar panels, a second 100 Ah battery and installed LED lights. We’d now like to change the old Electrolux 3-way fridge to a newer 12v compressor, since it’s not the best and we have enough solar power to forget about the gas. We’re currently looking at the Freeline 115 (couldn’t provide a link since I’m new here).

I made a schematic with all the electrics in our van. In the center there’s this main control-unit where the various loads and devices come together and where the 230V-12V converter charges the battery when plugged in. For now (not on the schematic), the 3-way-fridge is hooked up to the “7. FRIDGE+” connector, which is internally triggered by the “8. IGNITION 12V” bus to only provide 12V when the engine is running.

I have a couple of questions:

  1. as you can see, there are some free bus bars on the central control unit (AUX1 and AUX2). Would I be able to power the new compressor fridge with 12V directly from one of these two connectors?


  • the connectors have a built-in 8A-fuse. According to the manual, the Freeline draws 6A max current, so the fuse seems sufficient, correct?
  • the AUX1 and AUX2 have a built-in switch, which would allow me to easily turn power off to the fridge. However, the Freeline manual demands a switch capable of 15A-load (which seems weird, since it draws 6A max) and I’m not able to check the amp-rating of the built-in switch. Problem?
  • I could simply re-use the existing fridge-cable and wire it to the aux-bus instead of the FRIDGE+ bus. It’s a 2.5mm cross-section which is on the small side for a distance of about 4 meters, but then again, the old fridge has run perfectly on this wire for ages (and it used more amps), so I figured that wouldn’t be a problem?


  • wiring the fridge to the main bus-board might not be as efficient as wiring it straight to the battery. That would also be an option, but that would mean I’d have to drill an extra hole through the chassis to go from the battery underneath the passenger seat to the kitchen and I’d have to buy, wire and install an extra switch and fuse.
  1. I’m reading all kinds of different opinions online, but would it be bad for my battery life when hooked up to shore-power to simultaneously charge (230V) and discharge (fridge) the battery? I wouldn’t think so, since lights, pump etc… also discharge the battery, but of course they’re not running 24/7 like the fridge would. On average the Freeline 115 uses 35 Ah/day (24 hours).

  2. Side question: if you take a look at the electrical schematic, do you see a point where I could add a decent battery monitor through a shunt? If I understand it correctly I should wire it in between the Battery- and Loads-, but in my case the mains board sits in between. Or could I just bridge it in between bus 6. LOADS- and bus 9. BATTERY-?

Thanks a lot!

I’m not familiar with the Aristocrat main control unit in your schematic, but it appears to be designed to act as a positive bus bar and a negative bus bar for all your electrical loads. If this is the case, then I would send all grounds to the Aristocrat, and then ground the Aristocrat to one location in your vehicle, preferably the OEM ground point where the vehicle starter battery is grounded.

I would not additionally ground your leisure batteries and inverter to locations that are different from where the Aristocrat is grounded, as shown on your schematic. Instead, I would just send the ground from both leisure batteries to 9. BATTERY- on the Aristocrat with an appropriately heavy wire. Then you could install the shunt for the battery monitor inline with that heavy wire, just before it reaches the 9. BATTERY- terminal. I am assuming the Aristocrat uses some power too, so it is considered to be a load on your leisure batteries as well.

For all other devices (including the inverter, water pump, fan, and all your lights), I would send the grounds to a negative bus bar that connects to 6. LOADS- on the Aristocrat.

It seems your new 12V fridge could go to AUX1+ or AUX2+. Probably the Freeline manufacturer could tell you why they require a 15A switch, when the maximum current draw is only 6A. An 8A fuse should be enough for that 6A draw, but the wire would need to have over 8A capacity so that the fuse melts at 8A before the wire insulation does. If your old fridge draws more than 6A and the wiring has proven sufficient, then you could re-use that wire (unless it looks damaged).

You could wire the new fridge directly to the batteries, but then you start to deviate from the intended design of the Aristocrat as a positive bus bar, and you get more complicated wiring.

I can’t comment on whether it would be detrimental to charge and discharge your AGM batteries at the same time.

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Thanks a lot for your long and helpful reply!

To be clear, my schematic is how the van is actually wired up now. The first leisure battery and starter battery are grounded to the same (OEM) spot (under the hood) but as far as I can tell there’s no direct ground connection from the Aristocrat main control unit to that same spot. There’s a ground connection for the 230V-input, but that’s just wired to the metal chassis of the Aristocrat. The main connection from the Aristocrat to OEM-ground is through the -terminal of the leisure battery.

The second leisure battery was installed later (together with the 1500W inverter) and they’re both grounded to the (metal) chassis underneath the passenger seat.

Fan, lights etc… are indeed connected to the 6.LOADS- socket; the pump is connected straight to the 9.BATTERY- socket, but I don’t think there’s a specific reason for that (I suppose they ran out of connections).

I’m going to try out the shunt inline with the 9.BATTERY- wire as you suggest! My guess is that won’t measure anything in/out from devices wired straight to the second leisure battery, but for now that’s only the 1500W inverter which we don’t use that often, so that won’t be too big of a problem.

As for the fridge, all clear concerning the fuse and wire; I’ll try contacting Freeline to ask about the switch (and then somehow try to determine the amp-rating of the old switch :slight_smile: ).