Need Advise When Dry Camping

[Dwmooney]

Just about the time this Covid 19 issue started we purchased a 2005 Winnebago Vectra. I would appreciate some advise on electric power management. Along with all the other issues the coach has an residential frig? Thanks Dan

[DavidM]

A residential fridge is a problem because they are much less efficient than a DC powered Danfoss compressor fridge that is used on many newer RVs or the LPG based absorption fridges that use almost no power, only propane.

So a couple of solutions to deal with it while dry camping:

Run the generator 3-4 times a day for an hour or so to cool down the fridge and leave it off otherwise. Set the temp down in the low 30s and it will probably cycle from that temp to maybe the low 40s 5 hours later with the power off before you start the genset again. You do have a genset don't you?

Even with a genset another solution is to use an inverter if you have one to make 120V AC from the DC in the batteries to keep the fridge running. The problem is that it will pull a lot of DC from the coach batteries so you have to run the genset to recharge them, so why bother, just run the genset every 6 hours as above.

Putting several gallon milk jugs inside will provide a bit of heat sink buffer for the on/off times.

A much better solution is to install a propane RV fridge. Do you have sufficient LPG storage? Another solution is to install an efficient DC based RV fridge. But you have to have enough battery capacity with solar to help keep the batteries recharged and a larger converter of 80 amps or so with larger wire to let the genset recharge the batteries faster to keep its running time down.

David

[Lv2Roam2]

There are lots of options for power management when dry camping based on what your needs are:
- Generator runs, either timed or with AGS
- Larger battery bank
- Solar - portable or fixed
- Reduced consumption

Each has pros and cons, and particularly, the generator runs are influenced by 1) are you at the coach to run it, 2) are there limited hours, 3) are you knowledgeable about the differences between bulk, absorb and float stages and the efficiency of generators. Over on the IRV2 site you can read for hours on the topic of boon docking and power management.

Bottom line: we boondock extensively with a very large solar array. I think the most cost effective way to manage power, if you boondock a lot, is a small to modest portable solar panel system and an extra true deep cell battery or two.

Questions welcomed ... get out there any enjoy!!

[DavidM]

Well I agree that a modest solar panel setup is a good way to deal with the power needs when boondocking. But the home fridge blows away that power need.

Even an Energy Star fridge will require 2 amps AC for a 25% duty cycle. 2 amps AC means 20 amps DC or about 120 Ahs DC daily. That is a lot to replace with solar.

A Danfoss type compressor fridge will cut that by 1/2 at least. An absorption fridge will require only 10-15 Ah daily for controls and the propane solenoid.

It is tough to dry camp with a home fridge.

David

[Jimm]

Do you have the specs of the fridge?
You may try doing partial solar to minimize the amount that your generator will run. Maybe do a 2 100watt portable solar setup. This will help but it won't be enough to not have to use the generator. Depending on the fridge specs you may need 400 or 500 watts of solar panels or more and these will need to be in full sun all day.
Jim

[creativepart]

I would suggest a good first step - install a shunt-based Battery Monitor. You RV probably has a battery monitor that displays the state of charge in volts. It’s really difficult to get an accurate read with these. The voltage range between fully charged and 50% empty is pretty slim and the batteries have to rest too long between charging or usage to get a true number to read on the volt meter.

A shunt-based BMK calculates all power in and out of your battery bank and displays the state of charge in percentages. Plus it doesn’t need the batteries to be at rest to provide the true SOC.

They’re easy to self install cost $200 or less and will help you determine how much power you’re using and how much power you are putting back in your bank with the generator or if you add solar.

The BMK is the ideal first step and THEN you can decide on solar, AGM, Lithium, etc.

[gurroz]

Dwmooney, you did not say what your current battery bank looks like. If running the generator several hours a day I would buy a small 2000 - 2200 whisper generator. It will use much less gas and be quieter than the on board gen. I would also look at a portable battery bank like a Jackery or Bluettie to run appliances and televisions at night which will save your coach batteries for your frig and furnace if necessary. Also if your interior lights are not LED switch them.