I want to connect 12V output from TWO AC200Ps in parallel?

I have two AC200Ps in my van conversion. We carry some medicine that must stay refrigerated.

I plan to have one unit powering our AC and DC load and always being charged when the van is moving and the second AC200 would be a backup just for the fridge.

We often go to sleep with the Air conditioner on and it usually loses power after a few hours. At that point the second AC200P would take up just the 40 watt 12V load to keep the fridge running.

I could use a transfer switch but I’d rather not add additional failure points.

Running an AC200 series for just a 40 watt 12 volt load does not yield high run times. The large overhead from the regulated DC high amp output consumes considerable power with just the regulation process.

Yes, i know a fully charged AC200 will run my fridge for a long time and if i was just worried about a little food in the fridge it would not matter.
But I want the best chance of never losing DC power.

If this was just a battery I would not be asking this question. the issue is whether or not the control board will care if there a voltage present at the 12V output.

Here’s what it looks like; after a day of travelling both units are fully charged from the alternator and solar. One is powering the whole van, the other has AC turned off.

We fire up the AC and it runs a few hours and drains the AC200 to zero and it shuts off. In the morning we turn AC power on and cook breakfast on an induction cooker. Then the sun comes up and begins recharging.

All of this requires a human to turn things on an off. I’d like to parallel the DC output to reduce the likelihood of ever losing power to the fridge.

If this is not a problem then i would run ALL the DC through this circuit so we’d notice of the lights or the water pump stopped working.

I have seen post from Bluetti stating that you cannot connect multiple 12 V output from the Bluetti’s in parallel. I have never tried it myself

For my part, I wanted to put the 12V output ports of my 2 AC200MAX in series, and Bluetti advised me against it. I imagine that Bluetti will also strongly advise against putting the 12V outputs of your AC200P in parallel. Even if it should be possible to install anti-return Schottky diodes to block current returns and limit the risks of putting them in parallel (as for solar panels and battery), Bluetti may not like this. I have an idea for you: maybe you could connect the 12V cigarette output of your first AC200P, the one that is powered by the car or solar panel (and has the AC and DC outputs enabled) to the solar input /12V car recharging of your second AC200P (the one that serves as a backup) – you already have the two cables you need: Car charging cable (car to XT90) and XT90 to aviation plug. The idea is: you connect your refrigerator to the 12V socket of your second (backup) AC200P. This one is used in “pass through” mode because it is powered by the solar input/12V car power supply by your first AC200P. So, if it is out of order (empty battery), then it is your second AC200P which takes over with its own battery… you then have backup for your fridge
And it complies with the rules of use of bluetti for the warranty I think.