What size generator (output) should I get?

[LJ-TJ]

Sent: 5/10/2006

I'm looking at 6.5s anyone got any thoughts on what size would be the best.  I kinda had the idea  a 6.5  incase I wanted to run an air compressor to run an air gun if I needed to change the tires on the road. Or if we got boon docking and some one needed power we could help out. ?

[firebug911]

Sent: 21/05/2006

We have a 6.5 and I like it... we can run both roof a/c if needed and plug in a buddies trailer if we just run 1 a/c.... The one I have you can hook it up for 230 volts and split the circuits for 2 115v. outputs..... That is what I did.

[ClydesdaleKevin]

Sent: 26/06/2006 

I bought a Generac 4800 watt, and its great!  1200 bucks DELIVERED from Norwall Power Systems, and its set up with 2 circuits:  one 30 Amp, and one 20 amp.  I wired the 30 amp to the coach, and the 20 to an outside outlet, to power "other things", like compressors, power tools, etc. 

A year of hard use later, and its still going strong.

Kev

[myshoebox1]

Sent: 27/06/2006

I had picked up a 3500 Wen from Menards for only $279.  It fits in the spot but will have to pull it out to run.  But for the price and size I was well pleased.

Shoebox

[Froggy1936]

Harbor Freight has terrific deals on Generators  Frank

[ClydesdaleKevin]

But if you buy a Harbor Freight genny and use it at a campground, your fellow campers will hate you!  They are by far the most annoyingly noisy gennies out there.  And you can't even get used to them as white noise...they ocillate, and surge, and up and down and down and up...grrrrrrrrrrrrr....lol!

Kev

[Oz]

I'd like to revisit this question for a more difinitive answer.  "I can run this, that and the other thing with this size generator" really doesn't do whole lot as far as being able to figure out what size is truly appropriate based on need.

There certainly is such thing as overkill and the result of it... overcost... Yeah, it's good to know you have more power than needed but, if you only really need say a 3.5kw and you buy a 7k, you spent a lot more $ for it and it's going to eat more gas too... and no point to it.  TJ was looking at a 6.5kw.  I don't think he'd need something anywhere near that big just to be able to run an air compressor to inflate his tires. 

Sooo... how DO you determine the right generator output based on your RV's equipment and use based on a deman?

(I feel pie charts and line graphs, algebraeic equations and mathematical theorems being conjured up by Dave already...)

[ClydesdaleKevin]

Amps X Volts = Watts.  If you have a 6500 watt generator producing 120 volts, that gives you 54.1666 Amps to play with.  (Watts / Volts = Amps).

I would imagine that the output is limited to 30 amps though...our 6.5 kw Emerald III genny has two circuits coming out:  One 30 amp that powers the coach, and the other a 20 amp that just goes to an outlet in the genny compartment (and I think runs the rear AC unit when both are on with the genny running).  Most compressors that are small enough to carry around are going to draw 15 amps or less when running.  So the 20 amp circuit by itself would be more than adequate to run most power tools, without even tapping into the 30 amp coach circuit. 

If your power needs aren't that great, then a smaller unit would be just fine...and lighter and cheaper!  And generally quieter and more economical to run.

If you want a full 30 amps of usable power, then 3.5K is the minimum size genny required at 120 volts (3500/120=29.1666)

Kev

[JDxeper]

Here is an article on size'

http://www.everything-about-rving.com/what-size-generator-do-i-need-for-my-rv.html

[DaveVA78Chieftain]

Kevin basically explained size.  There is a reason smaller RV's with only one AC typically only had a 4KW generator .  That is all that is needed to support a 30 amp rig (4000/120 = 33 amps).  Like Kevin said, larger RV's with two AC's typically had a larger 6.5KW generator (6500/120=54 amps) that are typically spilt into two seperate circuits (Normally 25 amp / 25 amp).

If you do not have an AC, then you can should be able to use an even smaller generator.  Say a 2.5KW (2500/120=20 amps).

The older 1800RPM generators run quieter than the newer 3600RPM units

The more expensive inverter generators run quieter partly because they run at low RPM.  Under heavy load the RPMs increase.

Dave

[ibdilbert01]

I think the best way to figure out what size you need is to make a list of everything in the RV that uses electric, figure out their required watts, then add them up.

I use a Kill-O-Watt meter (https://www.youtube.com/watch?v=1l_mo1jwh8Y) 

An example:

1050W - 700 Watt Microwave (You'll find they use more than their rating)
1260W - 13.5btu AC (These also very, newer ACs are more efficient)
200W - Fridge on electric (Again, these can very, mine only uses 60 watt)
600W - Coffee Maker
75W - laptop
60W - 24" LED TV
400W - 12v Converter (And again, can very greatly depending on size)
--------------
3645 Watts Total, if you used everything at the same time.


You want to buy a generator just a bit over what you need, and you need to keep in mind you'll probably never use everything all at once.   In this example, a 4k would be plenty.   The biggest consumers are always going to be the AC and Microwaves.  Your converter can be another energy consumer, depending on its size.

A good majority of RVs have a 30 amp plug, and as both Dave and Kev pointed out, a 4k Gen is capable of 33 amps, more than the RV is wired for.   A larger RV with double AC units, you'll probably want a bigger generator.

[Lefty]

We only use our genset to power the roof A/C while on the road... So we don't need anything bigger than the lil 4.0kw we currently have

Umm, and fridge while driving, gotta keep those groceries cold!!

and occasionally have the tv (a 19" LCD flatscreen which draws little power) or laptop plugged in as well.

Oh, maybe the coffee pot too, in case I want some hot coffee while riding...

Oh, and I can't forget the tv's surround system if the tv's on...

And there's a rear CD/AM/FM Stereo mounted in the back that stays plugged in...

Hmmm, I think our hot water heater has an electric heating element in it too... I might want to wash my hands or take a quik shower while in route...

Oh, one more thing... the Dirt Devil vacuum cleaner charger stays plugged in all the time too..

Dang, almost forgot my wifi router... and our two cell phone chargers. Hm?


  I might better get me a bigger genset.

[Oz]

Thank you all very much!  Really good info.

   

[bluebird]

My coach came from the factory with a 6500 watt genny. It only has 1 air conditioner, and is a 30 amp service. It is wired for the 2nd air and has switches inside to be able to run both on the genny only. On shore power you have to run one or the other. I have noticed that I can run every thing I want at the same time and still have power left. When I had the Itasca it had a 4000 BFA, and we had to shut down the air when the wife was fixing breakfest, or the genny started having fits.

We couldn't run the Coffey pot, microwave, toaster, and the air at the same time.We can now, and the genny uses less fuel running @ less than full load, than the old BFA did. If it goes out, I'll replace it with the same