12V compressor fridge not starting/staying on. Thoughts?

[80t0ylc]

Have you looked through the owners manual? I would think that there's a warning limiting what you can run on the back outlet. But, I agree that the designers should have specified an adequate gauge to run a fridge, which is a common mod used nowadays for an SUV.

 

[e9999]

^ No, neither manual said anything more than "don't exceed 120W". Nothing about fridges, electric motors, inrush current and the like. They're just trying to save a couple of bucks on the wiring, I assume.

 

[80t0ylc]

^ No, neither manual said anything more than "don't exceed 120W". Nothing about fridges, electric motors, inrush current and the like. They're just trying to save a couple of bucks on the wiring, I assume.

120 watts is 10 amps at 12V. Pretty much why Waeco or for that matter any fridge would have difficulty when the compressor kicks in. Might be why the Waeco had issues with your power supplies. They might not be "beefy" enough. I think that the spike in draw exceeds 10 amps during compressor start. The fuse in the side of my Nat. Luna fridge is 15 amp for comparison.

 

[e9999]

^ The 120W was for the battery circuit outlets in the trucks. Yes, the inrush current can be quite high and perhaps more than 10A for a very short blip, but typically the fuses in the truck won't react that fast, I would think. The 10A is standard for power outlets in trucks and it's starting fridges just fine normally if the voltage is high enough. So that should not be a problem with a battery unless the wiring is too skimpy.

I don't know yet what the issue is with the power supplies, though, it is possible that they were not capable of delivering enough instant power for the inrush surge. I may try it on a 200A supply I have and see what happens, but that one surely has a crappy waveform.