Residential refrigerator question.

[Eric H.]

I'm looking into the Dynamax DX3 as a home on wheels.

How do household refrigerators work in an RV? I know they run off the inverter, but what about while you're driving? Can you run the fridge? Is the alternator enough to keep up?

Can you dry camp without the generator running the whole time? I know it depends on how many batteries and solar panels you have, but lets say you have 2 180w panels in full sun and 2 group 31 house batteries with no other loads on, so when the sun goes down, the house is fully charged. Can anyone give me a ball park idea of how long the batteries will power the fridge via the inverter before you have to run the generator? Would it run 4 hours, all night? Just looking for a rough idea.

I know you can't run the A/C or Induction Stove without the generator, but could you live off grid with enough solar panels and batteries without running the generator? Obviously the answer is yes but how many batteries is that? 4, 6, 8? Any idea's?

Thanks

[Skyliner]

https://www.gonewiththewynns.com/rv-...igerator-power

Seems like you will burn about anywhere from 1,200 to 2,000 watts of electricity a day depending on your fridge.

That is a TON of usage about 195 amps of battery usage/day assuming 85% inverter efficiency at 2,000 watts/day

TO pull off this off, I personally would want at leas 900-1000 watts of solar and 800 to 1000 amp/hours of battery capacity (higher is better).

I have almost this amount of solar and battery capacity in my RV and I'm glad I have a propane fridge.

Your fridge should have had an annual energy usage tag on it when purchased new. Divide annual usage by 365 to get an idea how much energy it uses per day.

Good luck!

[Skyliner]

A Group 31 battery will have anywhere from 85 to 100 amps/hour capacity but remember, only 1/2 of that is considered usable if you care about battery life.


Let's say you have tow of these batteries giving you 100 amp hours of usable capacity (1/2 of max capacity). 100 amps x 12 volts = 1,200 watts of power.
With an 85% efficiency inverter, you will have about 1020 watts of useable power inverted to 120 volts AC for your fridge.

You may have enough battery to last a day for small fridge or 1/2 day for a larger one. This is assuming no other load on the batteries which is impossible.

Bare bones minimum I'd go with is:

4 banks of 2 golf cart batteries for 800 amp/hours of battery capacity
1500 watt inverter so you can run anything in camper off of it and one high power device at a time such as microwave, hairdryer, toaster oven, etc...etc..
900 watts of solar. Each 100 watt solar panel is wired in series in groups of 3 and each group of 3 panels is wired in parallel with the other 3 panels. This will give you about 60 volts to an MPPT controller which is more efficient at higher voltages.

This is not going to be cheap and a cheaper option is to get a propane fridge and use your savings for a nice quiet inverter generator

[Skyliner]

BTW, it is possible to run off grid all of the time and we do it EVERY time we camp. However, we have propane fridge, use only propane to heat our water, and have a propane stove.

Our solar system keeps us at 100% state of charge during the day and we have plenty of capacity in that our battery usage is about 15-20% each night. OUr main power usage is our forced air propane heater running almost all night cuz mountains get cold at night even during the summer and of course we watch a lot of DVD movies at night too which is about 10 amp/hours of electrify usage at 12 volts and we burn about 2 amp/hour from CO detector, fridge motherboard, heater motherboard, and entertainment system in standby.

Propane usage for fridge is about 1.5 to 2 lbs/day. Propane usage for heat is fairly high and with fridge and heat running about 40% of the time during the night we are using about 4 lbs of propane/night. We get about 5-7 days of usage on a 30lb tank but a lot of that is for HEAT!

Hope my replies help.