12V Fridge Electrical Issues

[RJZeiler21]

Hi all,

I'm having some electrical trouble with my coach I'm hoping someone can help with. I've got a 1976 Winnebago Brave D21, running the original Progressive Dynamics 30A power converter. Beyond the converter, though, all other 12V electrical is new in the coach, including LED puck lights, USB chargers, water pump, a few fans, and what I'm having trouble with, my 12V fridge (https://www.recpro.com/rv-refrigerator-3-3-cubic-feet-12v-stainless-steel/).

When I'm on battery power, the fridge seems to work perfectly. But, when I'm on shore power, and the fridge is getting power through the converter, a couple things happen: first, all of my lights flicker continuously while the fridge's compressor is running, and second, the fridge quits after awhile and I'll come back to find my food warm a few hours later. I thought that the fridge was quitting only when I used other 120V appliances in the coach (A/C, or the induction cooktop I installed), but just this weekend while camping, I left the RV for several hours while out hiking, with A/C and all other electrical loads OFF, except the fridge, and still came back to find the fridge turned off and getting warm. No breaker tripped, no fuse blown, but shutting off power to the converter (switching to battery power momentarily) and turning it back on gets the fridge running again, temporarily.

Does this sound like a power converter issue, or maybe my wiring size (I used 14AWG), or something else? If it's the converter, should I upgrade to a higher amperage converter to avoid this issue?

Thanks in advance for any help!

[Oz]

Or, I read that it requires 20amp service.  If it's not on a 20amp, it may have an internal shut off.  I think you may want to contact the manufacturer for specifics, but your original converter may need to be upgraded.

[ibdilbert01]

Because the fridge requires a 20 amp circuit, you will want to make sure you have it on its own wire, using the appropriate gauge of wire.  Because we are talking 12 volts DC, you need to keep distance in consideration with you wire gauge.   Here is a chart you can use:

https://www.engineeringtoolbox.com/amps-wire-gauge-d_730.html

The further away the fridge is from its power source, the bigger your wire may need to be.  Also make sure this run is fused so if there is an issue, you don't create a fire.    It is very important to size the fuse for the wire, not the device it is running.  If your run can only handle 30 amps, you need to make sure your fuse is 30 amps or less.  This way if you have a short, the fuse blows and the wire doesn't catch on fire. 

[Mlw]

and the fridge is getting power through the converter

This is your problem. You do not have a original Motorhome fridge.

Original Motorhome fridges come with three power supplies. 220 volt, 12 volt (only keeping the fridge on temperature when the alternator runs) and LG (gas). When on shore power the AC, fridge, microwave and other high power appliances get (like ibdilbert01 also says) their power directly from shore power and NEVER thru the power converter. This is clearly stated in all owner manuals I've read over the motorhomes I've seen the last year, (European or American) but also experiencing at work for a sailing yacht broker for 5 years.

The old converters just aren't made for today's power consumption. They are feeding power directly to the appliances and the rest of the power left is used to charge your auxiliary battery. This probably is also the reason why the Chassis battery isn't charged by shore power via these old converters. They are just not powerfull enough. It also just wasn't really necessary as the only accessory used in the '70s without the motor running was the radio which probably didn't exceed 6 watts power consumption. (How the hell it was possible to stay alive in the '70s keeps blowing my mind  )

For dummies: your fridge compares to a V12, your led lights to a V2. When they get the energy from the same supply fed by just one line. which one is going to consume the most energy and probably leave the other one out when law of physics kicks in???

You have two options,
- A high power modern converter (High priced option running in the thousands)
- Make a separate power supply for your fridge, (and other high power appliances who just aren't made to be fed by a 12 volt battery)

As everything seem to run fine as long as the fridge doesn't kick in i would go for the second option as this would be way cheaper, but when you think your powerconsumption will get higher in the near future there just isn't escaping the first option.

Explanation Power Converter: http://dave78chieftain.com/ConverterInfo.html