How to power a Carrier AirV Roof top AC

[RTS/Daytona]

Question for NICK

Will increasing the size of the "start Capacitor" and or "run Capacitor"" help a 13kbtu or 15kbtu  RV roof top Air Conditioner start easier on a smaller inverter ??

what sizes would you recommend ??

[FloridaCliff]

Here's my simple math reason for using my diesel generator for powering my A/C's when driving:

My reasoning assumes your going to have a generator anyway, I use a small inverter only for small loads and my refrigerator when stopped.

Using some of Seans numbers, which I thank him for as I was curious of 50DN loading vs fuel usage would be.

.4gph using 50DN, .6gph using diesel generator

To make it simple I am looking at 1000 hours usage

.6 X 1000 hours=600 gal, .4 X 1000=400, 600-400=200 difference, 200 X $2.60(current diesel price)=$520.00

Premium MSW inverter, 3000 watt min and batteries=$3000.00 (my figures)

3000/520=5.769  5.769 X 1000=5769 hours generator needs to run to equal cost of inverter/batteries alone.

5769/8 =  721  You would have to drive 8 hours a day for 721 days to get this many hours. Or basically 2 years straight @ 8 hours a day.

I did not include any incidental maintenace costs (oil, filters or battery replacements. etc) for the sake of this discussion.

Now, maybe you travel this way, maybe you don't.

I just took a two week trip to Minnesota and ran the generator only around 60 hours.  If your a weekender, its going to take along time to get to almost 6000 hours. On the other hand if your criss crossing the country like Sean does, or do a lot of serious boondocking, then its another story.

Just my way of thinking on this,

Cliff

[belfert]

I dry camp/boondock all of the time so I needed an inverter and battery bank anyhow unless I run the generator pretty much 24x7 for my household fridge. 

I bought my Prosine 3000 inverter for $900.  With two sets of batteries and the cables and such I am right about $3000.  My golf cart batteries didn't work the best so I went to different batteries.

[JackConrad]

   Another factor that I considered, which may not to that big of a deal, is that any horsepower that is being used to turn that big alternator is not available to the rear wheels when going up those hills.  Jack

[John316]

Another thing to consider is possibly rising costs of fuel. We have a lot more than 3K invested in our battery/inverter setup, but we rarely have to run the generator. We can even survive off of a supplemental 20amp sure power (if the airs aren't running).

We would like to sometime hook up to our alternator (50DN)to the house batteries (especially since we stripped the OTR air), but we are going to need to know how to safely do it. We are thinking that we will use isolator, but that is another post.

God bless,

John

[Sean]

   Another factor that I considered, which may not to that big of a deal, is that any horsepower that is being used to turn that big alternator is not available to the rear wheels when going up those hills.  Jack

Jack,

When we're in the hills, I turn the intertie off on the big upgrades, which gives that ~10hp back for climbing, then turn it back on for the downgrades, where it makes electricity for free.

In fact, the 0.3-0.4 I mentioned earlier was at fast idle.  In real-world driving, it works out to be more like 0.2, because its almost always free on the downgrades, and we are seldom cranking out the full ~200 amps across the tie.

-Sean
http://OurOdyssey.BlogSpot.com

[TomC]

I this is for your big rig, then I highly recommend an APU.  Now if you already have the roof top air mounted, you could get the Powertech APU which is just a 2 cylinder Diesel (either Kubota or Caterpillar) running a 5kw generator.  It clamp mounts onto the frame, and just needs fuel, 12v and cab mounted controls, and then you can hook up directly to your own generator. You'll then have endless power.  Good Luck, TomC

[ojgetaway32]

Okay, Tell me why a 2200 watt gasoline generator will run the darn thing but a brand new 3000w MSW inverter won't.  Ugh!  F*** it!  I'm gonna move where its cold.

Josh

[Len Silva]

Okay, Tell me why a 2200 watt gasoline generator will run the darn thing but a brand new 3000w MSW inverter won't.  Ugh!  F*** it!  I'm gonna move where its cold.

Josh

Josh,

That question has been answered multiple times already.  It's MSW, it won't work.  Now, somebody here could post a 20 page explanation of AC theory which would explain why it won't work, but it won't alter the facts.

A 2200 watt generator has a sine-wave output, the MSW inverter does not.

Now, even modified sine wave can vary considerably, usually related to the cost of the inverter.

One thing you can try is to monitor the 12 volt battery voltage as you try to turn on the air conditioner.  If it drops much below 11 volts, then you may just not have enough battery for it to work.
Here are a couple of pictures that may help to explain it.

[RTS/Daytona]

many of the better "modified sine wave" inverters - design thier waveforms to provide the same RMS voltage (area under the curves).

more like the picture provided

[ojgetaway32]

Okay, that makes sense about the generator vs the MSW inverter.  Funny how I have a couple of generators laying around that will run it but no PSW inverter.  Gotta love it.

Josh

[ojgetaway32]

Okay, here is what I did:  I took a shot on eBay on a brand new 6000-12000W MSW inverter.  I hooked it up to my batteries when it came and the darn thing worked!!!  I ran the truck engine on low idle for an hour or so and everything seems to be fine.  The cab and sleeper sure are cold!  I paid $426 with shipping from Michigan to Wheeling, WV.  If things start to go awry, I will upgrade my alternator.  All looks good now though.  Funny, the LED indicator on the inverter says 2200W while running so the inverter is barely even working.  The startup must be a killer draw!

Thanks to all who advised, counseled and chastised.  I needed it all.

Josh

[Van]

Thats great, what brand is it,thanks for the update