50 amp down to 110 question

[jonthefireman]

Hey guys, quick question.

So were heading out tomorrow for the weekend, and I'm curious if it's possible to pigtail my 50amp cord down to the 110 adapter and if that's enough juice to run the fridge overnight?

I've got all the pigtails, just never tried it. If nothing else, I'll run it on propane or generator.

[sundancer 87]

You should be able to power the refrigerator off your 15 amp adapter without a problem. But that's all you'll get unless you adapt the 50 down to 30 amps.

[HornedToad]

Don't forget about your converter...
With all the 12V stuff on it could pull up to 8 amps,
the fridge will need 6 amps to start and about 2 amps running.

Like sundancer said "That's all you'll get" on 15 amps.

These RV refrigerators run more efficiently on LP than AC. I would leave the fridge on propane and let the 15 amp plug run my converter.

[DesertRat]

I don't think they make a 50 amp to 15 amp adapter. You need to go 50-30 & then 30-15. I did it all the time with the Honda 2000 generator I use to have. I did keep the frig and water heater on propane & ran everything else with the generator. Once I moved up to a 2400 watt Yamaha I could even run my A/C. This was on my 2003 Teton 5th wheel.

[sundancer 87]

Originally Posted by HornedToad

Don't forget about your converter...
With all the 12V stuff on it could pull up to 8 amps,
the fridge will need 6 amps to start and about 2 amps running.

Like sundancer said "That's all you'll get" on 15 amps.

These RV refrigerators run more efficiently on LP than AC. I would leave the fridge on propane and let the 15 amp plug run my converter.

The refrigerator is a 'resistive' load, not 'inductive'. There isn't a startup load with resistive loads, it draws what it draws until the thermostat reaches its set point.

Motors, on the other hand are inductive and usually require three times the initial start amperage to get them going and then once running it's only the running amps needed.

[sundancer 87]

Originally Posted by DesertRat

I don't think they make a 50 amp to 15 amp adapter. You need to go 50-30 & then 30-15. I did it all the time with the Honda 2000 generator I use to have. I did keep the frig and water heater on propane & ran everything else with the generator. Once I moved up to a 2400 watt Yamaha I could even run my A/C. This was on my 2003 Teton 5th wheel.

http://www.amazon.com/Camco-55168-Po...15+amp+adapter

I think I have one of these in my stuff.

[DesertRat]

Originally Posted by sundancer 87

I think I have one of these in my stuff.

I wonder how I missed that. Guess because I needed to go from 50 to 30 amps & had one of those, I just bought a 30 to 15 after I got my generator. Or could it of been a 30 to 15 amp was cheaper than a 50 to 15 amp.

[HornedToad]

Originally Posted by sundancer 87

The refrigerator is a 'resistive' load, not 'inductive'. There isn't a startup load with resistive loads, it draws what it draws until the thermostat reaches its set point.

Motors, on the other hand are inductive and usually require three times the initial start amperage to get them going and then once running it's only the running amps needed.

Just quoting the chart on the Honda Generator site...

Honda Generators - Wattage estimation guide

"Reactive Loads
Reactive loads contain an electric motor, which requires additional power to start, but significantly less power to run once it gets going. Typically starting power is 3 times the amount of power to run the application. Examples of reactive loads include:

• Refrigerators / freezers
• Furnace fans
• Well pumps
• Air conditioners
• Bench grinders
• Air compressors
• Power tools"

Are they referencing the start up on the refrigerators inductive 12V fan motors?

[DesertRat]

Not sure I would take all of Hondas loads as 100% correct. My Yamaha 2400e ran my 15,000 btu a/c with no problem. We could run it, the converter, tv & dvd player & some led lights with no problem. This again is on my 2003 Teton 5th wheel. Did this for eight years with no problems.

[ewarnerusa]

Horned Toad,
I would guess that the Honda chart is referring to residential refrigerators and freezers which use a compressor that requires a big oomph to first start.
Most RV style refrigerators and freezers are absorption style and don't use a compressor. I don't claim to know how either works completely, but that is my understanding of the difference.

[HornedToad]

The Honda chart specifically refers to an RV Refrigerator when referencing a higher start up load.

Since the Rat has already called their numbers into question and I know Sundancer & USA's comments about the AC heating element in an RV fridge are correct...

I'm going to try an experiment... with the load management display I can monitor the amp draw as I turn the fridge on/off and switch between AC & LP.

The only way to reconcile the start up amps on the chart is if the fans draw the higher load.

I hope nobody views this post as argumentative... this is how I learn about my RV!!!

[ewarnerusa]

I see, interesting. I have no idea what would require a surge in power demand from an RV fridge when on either propane or electric. Maybe they are referring to a smaller sized compressor-style electric (120V AC) fridge that some RVs have? I don't have a way of measuring 12V power draw in my TT; however, I've never noticed other symptoms from power surges from the fridge like sudden light dimming or reduced battery run time when running the fridge colder. I'm curious to see what your experiment reveals.

[DesertRat]

Mike
V series like my 3605 don't have the load management system. Be nice if you give feed back on heater fan, fantastic vent fan, electric water heater draw & any other things you can think of.

[sundancer 87]

I don't have a LMS either but I wonder, can it break down the usage in amps and volts? Switch from something using 12 volts ( a given for the most part), and display the current consumption of that device.

[HornedToad]

Fireman,

To answer your question in the original post,
after experimenting with my load management amp display...
the converter and fridge will draw between 5 to 10 amps.
So yes you'll be good on a 15 amp to 50 amp adaptor.

The load management display does not show the amps on 120V, so everything listed below is on the generator which should be the same.

Without any 12V items on and a fully charged battery the converter drew 3 amps when the ATS kicked to generator and settled to 1 amp. When I turned on all the 12V items on the front panel it pulled 6 amps.

The fridge pulled 4 amps on AC without any drop after 10 mins and 0 on LP. No noticeable start up on the fridge so I'm going to agree with the forum members over my reference to the Honda watt chart.

Amp draw on some of the other items...

Microwave 13 amps

Water Heater 11 amps, didn't let it get up to temp

Main & Front AC
Fan 3 to start 1 running
Compressor 12 to start 10 running

Rear AC
Fan 6 to start 3 running
Compressor 8 to start 5 running

Four TVs and Direct Box 1 amp

The 12V furnace fan, microwave fan/light and fantastic fan all added 1 amp each to the converter load.

[sundancer 87]

Good report, interesting the furnace fan drew so little while running.

[HornedToad]

Originally Posted by sundancer 87

Good report, interesting the furnace fan drew so little while running.

I don't think the increase in the amp draw on the converter from the 12V items is completely accurate because of the battery???

[sundancer 87]

I think the additional draw is due to the inverter having to work harder to maintain the battery. You're right about the battery part, the way to check the draw one those things would be with an inline ammeter or scope. With a VOM between the battery post and the positive buss bar you would have a good reading as you turned on each 12 volt thing.

[HornedToad]

Originally Posted by HornedToad

I don't think the increase in the amp draw on the converter from the 12V items is completely accurate because of the battery???

"is NOT completely accurate"