Using a inverter to operate Refrigerator while driving

[bigray]

Hi All,

I read alot about the safety hazards of driving with the propane one while driving. After looking at the gas lines this is certainly a hazard with our clippers. That's assuming all propane tanks are behind the driver seat bolted to the chassis underneath.

At any rate, a blowout would certainly rupture the gas line causing fire or possible explosion. I plan to re-route my lines; however, I like to use a converter to operate my refrigerator while driving.

Has anyone attempted this? I have a Dometic RM760 and would like to buy an inverter to operate it while driving. I don't know what size (i.e. watts) I need to produce 120 volts. Also, I don't know what size alternator I need to do so. Perhaps the one I have will suffice. The refrig is 275 watts.

I know I have to do some further research but I was hoping one of you have a setup like I'm describing.

Please let me know!!

[Shayne]

Yeah, if you have enough battery, you could do it... but just for kicks, I tried.

According to my fridge, it's rated for 1.6 amps at 120V, that's a little under 200watts.  I have a 300 watt inverter.. so I hooked it up to see if it would work. The inverter went into overload and didn't come out.  I measured the DC load at over 17amps.

One thing against you is that converting DC to AC is not 100% efficient.  The more you pay for an inverter, perhaps the more efficient they are.

The other thing is that generating HEAT with electricity it hard work...  it's a constant load, not like a motor or something where it might have a little surge load, then taper off once it gets running.

To get 275 watts out of 12V DC, you're going to need 23amps of power.. and that's at 100% efficiency.  Figure 20-30% loss there and you're going to need 30 amps, maybe more.  That's a lot of juice for a sustained load. Hope you have a roof full of solar panels because your alternator is going to cry if you do that.

From what I understand about the 3-way fridges is that the DC side of them doesn't use nearly as much power.  It's more of a maintenace mode to keep things from spoiling and doesn't create the cold that AC or Gas does.

After seeing this, I'm going to look into setting up a gas bypass valve that would allow attaching the small Coleman Propane bottles at the back of the fridge.  If I can find a small enough valve, the bottle will fit. If I come up with anything, I'll let you know.

[bigray]

Thanks for the info Shane. I was going to get an inverter this week. I had planned to get a 400 watt one. I know it demands a bit more power but I wanted to make sure that it was sufficient.

I was planning on connecting the inverter for the refrig to the existing house battery or a second house battery.

While driving, I hope the battery will be continually charged. You must factor in my ignorance of electricity. I'm learning about electricity as I go.

Seems as if you have done your homework. That being the case, how much drain is it on the alternator to charge the coach battery while underway?

[Shayne]

Seems as if you have done your homework. That being the case, how much drain is it on the alternator to charge the coach battery while underway?

I have not measured that because it's so variable.. but we only have 60 amp alternators, unless you've found a higher power one that fits. If you are not using any accesories, it's not much of a load as long as your ignition system is in good shape... but take a cold rainy night and add lights, heater and wipers and now it's having to work a bit.... add a 30amp fridge to that and I just don't think it would last long.

One thing I did not try was lowering the thermostat below where I usually keep it to see if it would draw less power.. I'm not sure how that would work.  Maybe it would cause the fridge to draw less power, but still help keep it from getting warm in there. maybe I didn't quite FINISH my homework

[bigray]

Shane,

I'm reading right now on how much power it take to recharge a battery. You are correct, there are alot of variables - rpm, ambient temp, other consumers, etc.

I have a brand new alternator and the guy at Autozone said that it was 63 amps.

I figure if the alternator is simply replenishing the charge of a secondary battery as oppose to carring the complete load of the inverter, this would work.  Again, I'm not to electrical incline but my simple mind says that this should work. I have to figure out how many amp it takes to maintain a charge of a second battery.

[bigray]

Well since my last post, I've replaced my RM760 refrig with a Dometic RM2510. It operates at about 1.3 amps.

I bought a 350 watt Vector inverter from Walmart ($44) and connected it via a cigarette lighter plug which is connect via the fuse panel.

When I attempted to use it to operate the small TV/VHS combo last weekend the low voltage alarm sounded when I had the coach A/C and headlights on at the same time. The TV uses only about 80 watts.

I've gotten conflicting feedback on how the inverter should be connected to the power source. I've read that it should be connected directly to the battery with a interver producing that wattage. Others say the cigaretter lighter connection is find as longs as you are pulling wattage lower than 150. The inverter came with wiring for both type connections.

Bottomline, given that I got the alarm with a TV that requires less than 100 watts there's no way on earth I'm about to plug my $900 frig into it. I'm going to have to do a bit more homework and tinker around with it a bit more.

When I replaced my alternator the young fella at Autozone said that I couldn't get a bigger alternator for my vehicle. Subsequent to that I spoke to one of the "old heads" that knew what the heck he was talking about and it turns out that I can get a 90 amp ($100 more in cost) as oppose to 63 amp. But when I think about it, is it worth the trouble just to run the frig. I'd have to be concerned about the existing wiring being adequate for the 90 amp alternator. Might be counterproducting in my ever-ending quest to get better gas mileage top.

For now, I guess I'll continue turn my frig on a couple days before a trip and use the generator to keep it cool. Besides, I'll need my genny to run the roof air becuase it's about to get quite toasty in this neck of the woods.

[dig]

I think the inverters are shrouded in a cloud of mystery. I have an 800 watt with a 1600 watt peak. I am not able to run my laptop and 17" LCD at the same time. One fires up fine, then get the alarm when I fire the other one up.

The secret seems to be all about peak power for when the item starts up. The lower wattage converters seem to have a low peak. I think you may have a tough time with the refrigerator and that small converter. I think the refer will have a tough time starting up. Refers seem to have quite an amp pull upon start.

I don't know that I have seen any difference with using the adapter plug in as opposed to the straight wiring. I have my large converter hard wired in, and I use the plug-in type for everything else.

The last time I was dry camping, I had to fire up the engine (got low power warning beep) at the end of the second movie I was watching (rainy night ). I was running the laptop, LCD monitor, and surround sound with a pretty large sub woofer. I think the sound probably draws more than the other two combined.

Here is my hardware cabinet -


Note: that gaping hole in the cabinet was there when I bought the Clip. I filled it up with the monitor The articulating arm allows me to pivot the monitor depending on where I am sitting/laying.


--dig

[bigray]

Now I know how you mounted the monitor I saw in the rally photos. I forgot to ask you how you mounted that puppy.

At any rate, thanks for the feedback. I think I'm just going to give up for now and use the genny to operate the frige like I said. The little TV/VCR combo I have works fine plugged in the lighter. However, there is a little small fuse that blow from time to time. I have to take the back off the the TV to replace the fuse. I just used the inverter to keep from going through the trouble of replacing the fuse (can you say LAZY).

Have you tried to get a TV signal through your flat screen. I guess you can play DV's on the laptop but what about VHS? I'd like the idea of a flat screen as saves lots of space!

I have a metal TV stand built for my TV. It's mounted where yours is; however, it mounts to the bottom of the overhead cabinet. It works great. But now that I have put a bed on that side I have to remove the TV mount in order to flip the bed out. The mount drops down in the path of the back of the couch that flips out.

Also, do you have trouble with DVD skiping while driving. That's my concern about getting a TV/DVD combo. Too, we have so many VHS's that we've bought or inherited. We have a cheapo Wal-mart DVD at home. I've thought about putting it in the RV but I'm sure if I hit a bubble gum wrapper on the road, it would skip. (Heck the DVD would probably jump out the play, that thing is so cheap).

Let me know what I would need to use a flat screen like your. What type of reciever I wold need to make it a TV essentionally!

[handyman]

Hay Ray just saw a tv with dvd and vhs built in can't remember if it was Target or Walmart but looked sweet  I'm putting a flat panel in the fifth wheel when it gets here that way when were going to pull out I just lay it in a drawer and go also a dvd and vhs combo in the closet on a wire rack wont even be seen getting close ordered the monster truck last week

[dig]

Now I know how you mounted the monitor I saw in the rally photos. I forgot to ask you how you mounted that puppy.

At any rate, thanks for the feedback. I think I'm just going to give up for now and use the genny to operate the frige like I said. The little TV/VCR combo I have works fine plugged in the lighter. However, there is a little small fuse that blow from time to time. I have to take the back off the the TV to replace the fuse. I just used the inverter to keep from going through the trouble of replacing the fuse (can you say LAZY).

Have you tried to get a TV signal through your flat screen. I guess you can play DV's on the laptop but what about VHS? I'd like the idea of a flat screen as saves lots of space!

I have a metal TV stand built for my TV. It's mounted where yours is; however, it mounts to the bottom of the overhead cabinet. It works great. But now that I have put a bed on that side I have to remove the TV mount in order to flip the bed out. The mount drops down in the path of the back of the couch that flips out.

Also, do you have trouble with DVD skiping while driving. That's my concern about getting a TV/DVD combo. Too, we have so many VHS's that we've bought or inherited. We have a cheapo Wal-mart DVD at home. I've thought about putting it in the RV but I'm sure if I hit a bubble gum wrapper on the road, it would skip. (Heck the DVD would probably jump out the play, that thing is so cheap).

Let me know what I would need to use a flat screen like your. What type of reciever I wold need to make it a TV essentionally!

I don't do VHS at all, so that is not a big concern for me. I'm not much of a broadcast TV guy, but I have a USB TV tuner for my computer - http://www.hauppauge.com/pages/products/data_pvrusb2.html This device allows you to use composite inputs for a VHS deck as well. When I pull in somewhere that has a cable connection, I will run it into that. I can use it with the antenna on top of the Clip as well, but I have not bothered with that yet.

When I plug in a movie while driving (usually music videos or a movie I have seen 100 times), I just use my in-dash player. I have a Pioneer unit that has a 7" pop-up monitor. I am able to send the signal from the laptop up to the in-dash display, and will someday use that with the GPS software I have for the laptop.

The price of flat panel TVs is going down, so that may be an option for you as well. You can have a DVD/VC player connected, and easily hook up shore cable to it. I just figured I would get more use from a monitor, as I don't go anywhere without my puter

I can send you some links for different mounting options if you decide to go that way. Let me know. I found quite a few places, and found some inexpensive options.

I know there are a lot of conflicting opinions on running the fridge on propane while driving, but that is what I do. I just make sure I shut the valve when fueling, and then open it and relight once I leave. Seems that there are a lot of discussion on either side of that, but it works for me, and I haven't blown up yet



--dig

[handyman]

No like I said we already found the plasma we want and were going to put a dvd vcr combo unit in the closet thats right behind the tv one little hole that wont be seen and it'll look like it came with the rig ow by the way we sold our Clipper and were getting a 37 ft fifth wheel and going full time work sucks so were going to injoy what time we have left sorry to say the clipper just wasent built for this

[dig]

No like I said we already found the plasma we want and were going to put a dvd vcr combo unit in the closet thats right behind the tv one little hole that wont be seen and it'll look like it came with the rig ow by the way we sold our Clipper and were getting a 37 ft fifth wheel and going full time work sucks so were going to injoy what time we have left sorry to say the clipper just wasent built for this

Yea - I was more directing towards BigRay about the flat panel. I could only dream of having a plasma in there!!! Should be awesome - enjoy



--dig

[handyman]

Plazmas are really coming down fast Costco has 15 and 17 in on for under 500 and they come with a built in dvd playeron the side of the screen

[Rodney]

Boy do I like the idea of that WinTV Dig.. did you purchase it from the site you posted? I am sure my dell 1100 would run it,  an sure sounds handy  
is 150 the going price?
Thanks

[dig]

Boy do I like the idea of that WinTV Dig.. did you purchase it from the site you posted? I am sure my dell 1100 would run it,  an sure sounds handy  
is 150 the going price?
Thanks

I am pretty sure I got mine from Fry's for around $100.


--dig