Explain frig on a class a. Please

[jts140]

Kids getting older. Driving soon and now I am looking into a used DP for wife and I. Owned several travel trailers in the past, always had electric/propane refrigerators. As I look online I see class As with residential refrigerators. I take it will have run on batteries while not driving or plugged in.

With good batteries how long is it safe for. I know this is opened ended, but some basic answers which can help me in my search would be great.

[jts140]

Thanks all. Appreciate all the answers, was only worried about a half day stops to bike ride or such...

[Dale_Traveling]

two-niner wrote:
Seattle Steve is correct.

Kerry

I'll second that. A residential fridge is very power efficient because of consumer demand to reduce home electrical costs. A good fridge will stay cold for hours off power. Last hurricane related power outage I didn't need to drag out the home generator until the next day when the ice cream started getting soft. But I will say if my general outing plans included a lot of time off the grid I would stick to the propane powered fridge.

[two-niner]

Seattle Steve is correct.

Kerry

[Seattle_Steve]

WyoTraveler wrote:

jts140 wrote:
Kids getting older. Driving soon and now I am looking into a used DP for wife and I. Owned several travel trailers in the past, always had electric/propane refrigerators. As I look online I see class As with residential refrigerators. I take it will have run on batteries while not driving or plugged in.

With good batteries how long is it safe for. I know this is opened ended, but some basic answers which can help me in my search would be great.

When you are looking at RVs open the refer door. Check out power requirements. Divide 12 volts into wattage. How long can you pull that amps and run your batteries down to only half. One I looked at was 650 watts. (54 amps) You need to do the math on the one you are interested in. May be lower than that. 54 amps drain for 12 hours back to 650 amp hours. Need a battery bank good for at least 1300 amp hours over night just for the fridge then add another 3 to 400 for rest of RV Battery bank capable of 1500 to 2000 amp hours would handle the job. The coach I looked at had a 2000 watt inverter and 4 t2 batteries @ $500 each. Still very marginal for even 8 hours. The big problem is how long will you have to drive to charge those batteries back up again? Fridge drawing 54 amps and charging at 54 amp. your alternator will have to charge at about 108 amps just to keep up.

The big problem with your math is that you are assuming the refrigerator is drawing that power 24/7. It doesn't. In fact, it doesn't even come close to that. It depends on how often you open the door, but with our use the compressor only runs for about 5 minutes every 6-8 hours. I can't hear it when driving, but I imagine that most days when we are driving the compressor does not come on at all and it is drawing virtually no power.

[jauguston]

If your RVing style is traveling from power post to power post the residential refer works great. If you camp off grid (boondock) they are not such a good idea.

Jim

[G_Lewis]

I am shopping for a new DP. Most have a residential fridge with four 6v batteries dedicated to running the fridge when the generator or engine is off. Some of the ones I looked at have an automatic generator start circuit that starts your generator when the four batteries get low...around 12.4v to recharge them. These units also have two additional 6v batteries to run the coach lights, etc. Then there is usually two 12v batteries to start the diesel engine. Different units use different combinations, but you get the idea.

[JR45]

I just dumped the Not-So-Cold fire hazard and installed the Sansung 197, one of the best moves so far. By switching to inverter the coach alternator will charge the batteries going down the road. I just had to rewire so it would be on the inverter when switched because the Norcold was on a 110 line only.
JR

[wny_pat1]

They run off the inverter, which runs off the battery bank. Don't know if it runs off inverter or shore power when you are connected to shore power. Almost everyone I have read about on forums really like the residential fridges!

[WyoTraveler]

jts140 wrote:
Kids getting older. Driving soon and now I am looking into a used DP for wife and I. Owned several travel trailers in the past, always had electric/propane refrigerators. As I look online I see class As with residential refrigerators. I take it will have run on batteries while not driving or plugged in.

With good batteries how long is it safe for. I know this is opened ended, but some basic answers which can help me in my search would be great.

When you are looking at RVs open the refer door. Check out power requirements. Divide 12 volts into wattage. How long can you pull that amps and run your batteries down to only half. One I looked at was 650 watts. (54 amps) You need to do the math on the one you are interested in. May be lower than that. 54 amps drain for 12 hours back to 650 amp hours. Need a battery bank good for at least 1300 amp hours over night just for the fridge then add another 3 to 400 for rest of RV Battery bank capable of 1500 to 2000 amp hours would handle the job. The coach I looked at had a 2000 watt inverter and 4 t2 batteries @ $500 each. Still very marginal for even 8 hours. The big problem is how long will you have to drive to charge those batteries back up again? Fridge drawing 54 amps and charging at 54 amp. your alternator will have to charge at about 108 amps just to keep up.

[Ivylog]

Most DPs have an inverter so no need to run the generator to power the refer when going down the road. Unless you boondock a lot, the house batteries that come with the rig will be enough to keep the refer cold for two days running off the inverter. Most all electric rigs will have extra batteries for longer time off grid.

[PapPappy]

With a good battery bank, and some solar panels on the roof, you shouldn't even have to worry about it, if you plug in at night. Actually, you could probably go the whole weekend without power, depending on the capacity of your bank.

Keep in mind, you can also shut off the fridge when you are driving, or run the genset while you are on the road...we do that for our A/C.:)
I know that if my LP fridge craps out one of these days, I'll be going the residential route...we don't do a lot of boondocking, and I can run the genset for a few hours, to keep it chilled.