Coach Power while driving

[johndeschamps]

Can someone clarify if the engine' alternator charges both the chassis and house battery while driving? Asking because I would like to run a small space heater back in the house for the dogs (while driving) but do not want to kill the house battery or inverter in the process. Should I just use the furnace instead? I planned on turning on the propane for the fridge, but I am concerned about how much propane will be used by both the furnace and fridge running at the same time. And, getting back to my original question, is the house battery being refreshed by the alternator since I assume the furnace draws an electrical load as well. For context we are first-timers and will be taking a very first trip in our new to us 2016 RH 31xl rig from NY to FL on 12/14, and plan several overnight rest stops on our way down. The rig is currently winterized, and I plan on de-winterizing it when we get south enough away from freezing concerns. On that note, should we use straight rv antifreeze to flush the toilet, or can we mix is with water? Thanks in advance for the group's collective insight and wisdom.

[JimD]

Yes the engine alternator will give some charge to the house battery while driving. How much is somewhat up in the air. A lot depends on the wire size and run length.

If you are wanting to run a space heater off an inverter while driving I don't think there is any way the alternator will be able to keep the battery charged. I assume the heater would be 120 volts and be running off an inverter. The powered required in this configuration is very high.

I don't know what size heater you may have but here are some crude power requirements for some wattages.

120 volt 1800 watt heater = 1800 watts at 12 volts which equals 150 amp draw.

120 volt 1200 watt heater = 1200 watts at 12 volts which equals 100 amps.

120 volt 600 watt heater = 600 watts at 12 volts which equals 50 amps.

If you want to run an electric heater it would be better to run the generator if you have one.

You can use the furnace which operates off 12 volts and uses less than 10 amps. It should be OK to run while driving because it has built-in safety features to prevent problems if there is a flame problem. I don't think the wind would affect the flame.

Propane use by the fridge is not much. The furnace will use more but should still last for days depending on tank size.

Sounds like you will be in some cold areas. Being in Southern California I don't have a lot of cold weather experience unless you consider Californians freeze to death when it drops to the 50s.

[johndeschamps]

Thanks Jim. Yeah, it did not seem like a good idea. I think I will stick with having the furnace on. I do have a ONAN 4000 generator, but the Ford e-450 triton is noisy enough as it is without the generator running as well.

[SloPoke]

Our take on this??? Run the Onan when you can instead of Propane Furnace (because of the noise). At nights when you are sleeping (insert location here) will usually not have the Onan running and you will be consuming propane and 12v house battery power for keeping you warm with the propane furnace (while it is quieter than the Onan). and it is easier to fuel the Onan with the chassis... than stop for Propane somewhere....

[johndeschamps]

Just so I am clear, you suggest running Onan (and an electric space heater) while traveling if you need to warm the coach house, and propane furnace at night. I wonder what the former does to gas mileage / range. Is the Onan pretty efficient?

[don_kleinschnitz]

Originally Posted by JimD

I don't know what size heater you may have but here are some crude power requirements for some wattages.

120 volt 1800 watt heater = 1800 watts at 12 volts which equals 150 amp draw.

120 volt 1200 watt heater = 1200 watts at 12 volts which equals 100 amps.

120 volt 600 watt heater = 600 watts at 12 volts which equals 50 amps.

I think the current values may have an extra zero .

[Grumpy]

Originally Posted by johndeschamps

Just so I am clear, you suggest running Onan (and an electric space heater) while traveling if you need to warm the coach house, and propane furnace at night. I wonder what the former does to gas mileage / range. Is the Onan pretty efficient?

1/2 gal PER HOUR at half load. I doubt you'll even notice the difference in mpg only running the heater.

[msherw]

Originally Posted by johndeschamps

Just so I am clear, you suggest running Onan (and an electric space heater) while traveling if you need to warm the coach house, and propane furnace at night. I wonder what the former does to gas mileage / range. Is the Onan pretty efficient?

Yes all that said about running the Onan+ceramic 120vac heater v. LP furnace is correct. Yes Onan makes it more noisy. But there is one additional option:

Put up the house/cab privacy curtain and keep the driving side warm with the engine heat. When you arrive or need to stop - turn on the LP furnace and it will heat (30K BTU) the house side in a couple of minutes. Doesn't take long.

[JimD]

Originally Posted by don_kleinschnitz

I think the current values may have an extra zero .

The electronic formula for power is P=E x I (voltage times current). To get the current you would use the formula P/E. So for 1200 watts the current would be 1200/12 (1200 watts / 12 volts) which equals 100 amps. Trust me.

This is the reason inverters are only good for so much. The figures I used are just basic but get you in the ballpark. An inverter can't create power out of thin air it can only change the voltage. Pretty much the input wattage will need to be close to the output wattage.

[don_kleinschnitz]

Originally Posted by JimD

The electronic formula for power is P=E x I (voltage times current). To get the current you would use the formula P/E. So for 1200 watts the current would be 1200/12 (1200 watts / 12 volts) which equals 100 amps. Trust me.

This is the reason inverters are only good for so much. The figures I used are just basic but get you in the ballpark. An inverter can't create power out of thin air it can only change the voltage. Pretty much the input wattage will need to be close to the output wattage.

Oh, isn't that wattage spec at 120v not 12V?
There aren't too many appliance plugs that would handle 100A ?

[JimD]

Originally Posted by don_kleinschnitz

Oh, isn't that wattage spec at 120v not 12V?
There aren't too many appliance plugs that would handle 100A ?

Yes the wattage used is for the heater which is running at 120 volts. But, the inverter is basically a step-up transformer meaning it steps up the input voltage to some higher value. To get a certain wattage output requires approximately the same wattage input. All the inverter can do is change the voltage.

I just did a search for inverter wattage calculations and found a site that you can plug in your requirements. Give it a try.

https://www.batterystuff.com/kb/tool...-inverter.html

[ALJO]

Why not use your engine heat (Coolant System). Install an aftermarket heat-exchanger and some insulated hoses. You can use a manual valve or electric operated, also TH controlled.

[don_kleinschnitz]

Jim D,

Ah, I thought you were saying that is what the appliance would draw. You are talking about the current drawn from the battery ...doh!

[johndeschamps]

Originally Posted by ALJO

Why not use your engine heat (Coolant System). Install an aftermarket heat-exchanger and some insulated hoses. You can use a manual valve or electric operated, also TH controlled.

That would be a great idea if money were no object, but then again if it wasn't I would also be adding solar panels and lithium as well.

This is a grand experiment /adventure for my wife and I. We are not even sure we will like it enough to risk making further large investments beyond the cash we already laid out for the Red Hawk.

About 6 months ago my wife blurted out - "John, why don't we sell the damn house, buy an RV, see the country, and discover where we want to land as our new home base" (which will be anywhere at this point but NY or similarly run state.)

When I hear an idea I like I tend to run with it, as I have been thinking about this for years. The market is great for sellers where we live and we sold our house in 9 days over ask, with a small bidding war.

FL is our first stop to winter and see my mom, who is 87 and has not seen any family since the COVID SHTF. Hell, we are not even sure we will be able to see her when we get there because she fell and is now in a rehab center.

Anyways, I do appreciate the input. Just trying to learn the ropes to navigate this beast and increase our odds for success.

[pconroy]

Originally Posted by johndeschamps

About 6 months ago my wife blurted out - "John, why don't we sell the damn house, buy an RV, see the country, and discover where we want to land as our new home base" (which will be anywhere at this point but NY or similarly run state.)

Anyways, I do appreciate the input. Just trying to learn the ropes to navigate this beast and increase our odds for success.

Kudo's to your wife! Mine's in the same mindset.


It does take awhile to learn how to live in the RV. And I mean that in the grandest sense of the word. It's give and take. Whether storage or heating, it takes awhile.


What I've learned is that (a) there will be a solution and (b) there will be a few ways to solve the problem.


After a couple of years figuring things out, we've been happiest with a chill-chaser electric unit up in the AC. And then a 1500 watt tower sized space heater.

[Steve Hhll]

On our 24L we just use the chassis AC unit to cool the coach when driving, closing all but the vents we can aim toward the back and putting the fan on high. Works well in very hot weather, not sure why it wouldn't work for heating the coach in cold weather. Am I missing something?