Dometic AC 13,500 BTU Model, Wattage?

[DMerryman]

I am curious if anyone knows the AC wattage required to run a "Dometic 13,500" BTU model. I'm trying to size up for a generator/alternator for my 5'er. . I was looking at a Honda Eu2000i [2000 watts at 16. 7A] and was hoping that this unit would provde enough juice for the AC unit. . I have a 2001 Sunnybrook 24ckfs.



Any help would be appreciated. .



Thank you,

Doug M.

 

[rrl989]

I was recently looking into the same. There is an issue with compressors called LRA- Locked rotor amps. Thats the momentary current needed to start up the AC compressor. I believe it increases with temperature / Compressor Head pressure. Coleman AC's 13. 5 btu unit have an LRA around 60 amps, I believe that even the high effficient unit was 54 amps. One camper told me the Coleman powermate 1850 was able to run the Dometic 7100 btu. I wanted the EU2000 also.

I just gave up on the generator issue as the Honda EU3000 is to big and heavy for me. Yesterday, online, I ordered a Carrier AirV AC 13. 5BTU.



Ron

 

[RedRamer]

This might help.

Last summer on a long power cord - those for lawnmowers, when I turned on the air, it would blow the 15 amp fuse.

When I turned on the fan first and let it run for a minute or so, then moved it to air, it would not blow the fuse anymore.

The 2000 might be close enough, but from what I've read it's usually not enough.

It has an electronic overload and it's sensitive.

A normal gen will take the grunt, it will grind down to low speed, but it will often times take the load anyway, after the initial surge.

Best way to find out is to try it out, if you can.

If you do let me know, cause I've resigned to the fact I'll be buying a 1000Honda and forget the air.

I also have the same a/c.

 

['956Wheel]

Our TT has a 13,500 A/C unit and the Honda 3000 watt handles it but it is close. Fuel comsumption is greater than I expected due to just about full load. The reason I went with a 300o is due to weight... . camping just ain't fun when you wreck your back!



Mike

 

[Tom G]

Dip-Therm by Dometic AC

Excellent question on generator size. I wished the answer was as simple as the question but the answer involves lots of stuff.



First, of all lets look at the AC unit itself. Dometic makes AT LEAST two different 13,500 btu models. One is a 57915. 521/526 and the other is 57915. 621/626. For the purpose of this post I'll use the 37915. 621/626 because that's what I have on my 96 Aljo 5er.



Second, lets gather the information on RUNNING amps from the manufactures book.



Compressor running amps are 11. 0

Fan running amps are 2. 5

Total running amps are therefore 13. 5



Locked rotor amps are 54. 4



Now here comes the fun part. Airconditioners run on AC and not DC so you can't use ohm's laws to calculate the load because you are dealing with reactive inductance and capacitance and impedance instead of a resistive load. To make this story somewhat shorter - the unit is going to draw about 1400-1600 watts when running. This of course DOES NOT take into consideration the decrease in efficiency and increase in current when it get hotter outside OR when the unit first STARTS. Which takes us to our third point.



Starting current - that's our biggest problem here. As you can see a 2000 watt Honda unit will run a 13,500 btu unit just fine IF IT'S ALREADY RUNNING. However getting it started is the problem. Airconditions use capacitor start induction run type motors. I'll try and make this as simple as possible. Our electric AC motor has a locked rotor amp rating of 54. 4 amps. Now our rotor isn't locked (unless it's defective) but as far as the MOTOR is concerened during the first revolution or so the current required to get it spinning is very high. We are talking about milliseconds here and some phase shifting is going on and that helps decreases the current requirements BUT it still takes a lot of current to start an airconditioner.



So our big concern is not running current or watts but STARTING current or watts or SURGE CURRENT OR WATTS. Duo-therm by Dometic RECOMMENDS a MINIMUM generator size of 3. 5 kw (3,500 watts) for a single airconditioner in their instruction book.



So do you need a 3. 5 kw generator. Well maybe yes or maybe no it depends (don't you just hate double talk Some generators have a very high SURGE watt rating and could start the aircondioner just fine. Others may not have a high SURGE rating and may not be able to get the unit started.



A Honda 2000 is a fine unit but is PROBABLY too small for a 13,500 btu AC unit. A Honda EU3000i would probably work fine BUT I would try it on a hot day at the dealer with some lights on inside the trailer before I bought one. Remember, if the vent fan is on in the bathroom, lights are on over the stove and the stove vent fan is running you have taken several amps (or watts) away from your available starting current.



My old motor home had a 4kw onan which would start and run the AC and microwave at the same time EXCEPT on a very hot day (110+ degrees). My son-in-law has a Tioga motor home with a 2. 8kw onan and it will ONLY run the AC unit and a few lights. Remember it's not so much the running current it's the starting current. There are some things you can do to limit starting current like turning on the fan portion of the unit first and then let it come up to speed before starting the compressor. Remember, fan first then compressor.



So, something around 3kw sounds about right if it's not too hot and your not trying to light up the whole forrest at the same time your cooking hot dogs in the microwave



Happy camping

 

[DMerryman]

I want to thank you all for the in-depth responses. Again, thanks for widening my eyes to start up wattage/amps. I have been convinced that I will look for something along the 4kw [5kw surge]with a 30+ continous Amp rating. [Handle and wheels installed] I'd prefer to be a little over on kw's than under.



I just read from the Generac web site that a 12,000 BTU window mounted a/c unit is rated at approx. 1400 watts and will draw approx. three times that amount to start the unit.



http://www.generac-portables.com/customer_education/wizard.cfm



The 2000 watt unit would have saved the lifting task, I wouldn't have been able to use it!!! Not to mention the $800+ I would have spent.



Thank you gentlemen,



Doug M. :--)

 

[Barry]

Tom G: Tom, thanx for taking the time to bring all of us up to speed on the little generator units. I too am in the throws of wrestling with which one to buy. $$$ vs weight vs power. Again, thanx for the time and expertise! Barry, TH&RV Moderator.

 

[Tom G]

Barry - Happy To Help

I have also been looking for a lightweight generator for our 5th wheel and don't feel like spending about $2000. 00 for the Generac or Onan RV models.



Seriously considered the Honda EU3000i but it weighs about 135 lbs. which at my age is alot. Have considered the Yamaha 2800i (about $1100. 00) which is also an inverter model but it's just a little too small. It however only weights 64 lbs which is great. If you were going to use it in a campground however you would have to install some sound absorbing materials around the frame or maybe put it in a ventilated box to cut down the noise.



Our local Home Depot has a Generac 4 kw for about $760. 00 which is electric start. Weight however is like the Honda 3000 I would guess. Would also need lots of attention to reducing the noise levels for RV use.



Bottom line is - haven't found ANY generator/interverter model which fits my needs. Want about 3000-3200 watts and a generator which uses the inverter method of generating electricity. Oh almost forgot to mention inverter style generators which are;



Generators which generate AC which is converted to DC which is INVERTED back to AC. This type of unit provides very clean AC power with excellent frequency stability. Bring you laptops folks because they will work just fine. Also MOST inverter models vary the engine speed based on the current load which is a nice feature. With only a few lights running these units usually run just above idle speed. When the AC kicks on the engine speeds up to handle the load.



Lets go fishing and while were gone maybe someone will start making what we need

 

[The Sequel]

If you buy 2 EU2000s and hook them in parallel, you will get about 3200 running watts and 4000 surge. You have to buy an expensive cable to hook them together, but you will only have to lift the smaller EU2000s one at a time. This will also give you a quiet, inverter generator.

 

[Blu-meanie]

I have 1 EU2000i. It won't run the A/C, but I believe 2 of them will. I too don't want to lift 150lbs if I don't have to. Picking up 2 2000i's at 45lbs each beats lifting 1 3000i and you get more power at around the same price even with the overpriced parallel cord. I'm waiting to get over my tax payment before I order another EU2000i with the parallel cord. I could have bought more than 3 of them with my tax payment. Don't you love it?:{ :{

 

[dmurdock]

My eu2000 will start and run the a/c fine if nothing else is on... when using it i set the temp as low as it will go so the compressor doesn't cycle. I plan on buying another one of these little wonders so I can run them in parallel and not have to worry about it.



850 may seem a lot to pay, but after you've had one, you feel like you got a bargain. When the a/c isn't on, this thing will run for around 11 hours and it's so quiet you don't even notice it.



Another thing to consider...



I was talking to a fellow rv'er this weekend at the Nascar race, and he had a real neat setup. . he bought a 4500 watt onan out of a wrecked motorhome for 100 bucks... paid 600 to have it retrofitted into his 5'er (used a fuel tank for a boat to supply the fuel). This would be the perfect setup if you can run across a deal like he did...

 

[tgrfan2]

AC and generators

I just bought an EU 3000 for my camper after much soul searching. The manufacturer said my unit pulls 14. 5 amps and 41. 5 amps at startup. The breaker is a 20 amp and has never tripped. On my house power with a heavy extension cord attached the camper voltage drops momentarily to 90 and then recovers to 113. With the generator, it drops to 75 momentarily and then comes back to 118. Even with the 1000 watt microwave on it holds 116 volts. The overload light will blink on for a split second and then off. The generator will rev to max throttle, but then settles back to near low idle. I did not need AC last weekend, but running the camper frig etc. plus a 1500 watt ceramic heater I was able to go 12 hours before refueling.

The only problem I had was mistaking nearby generators for mine! It is so quiet that I can't hear it in the center of the camper with it sitting on my "back porch".

 

[Briar Hopper]

Great thread! I was about to post in this forum, asking which generator would be strong enough to run my trailer's A/C, then I discovered a whole bunch of y'all had already done beat me to it...

JCarrington, what's a EU3000 sell for, these days?

 

[tgrfan2]

EU 3000

I bought mine from Mayberry.com three weeks ago. There price was within several dollars of the cheapest I found and I actually talked to the owner. The web site gives you the phone number. He is a straight up guy. I am going to buy another one from him for a friend as soon as he gets through with the IRS!

 

[klenger]

Problem with my EU2000

I reciently bought an EU2000 from Mayberrys and have used it several times. I got it out yesterday to do some work on the camper, and couldn't get it to run correctly. I had to keep the choke partially on to keep it from dying, even after it had warmed up. I figured I'd have to take it in to a local Honda shop to have it serviced, and expected to hear a story about buying on the internet and then expecting local service. Oh boy. They short end of the story, is that I was having a senior moment and was operating the choke lever backwards. When I actually turned the choke off, it ran perfectly.

 

[tgrfan2]

senior moment

Last weekend I got out and refueled mine. Started it back up and went in to turn on the coffee maker. Just as I hit the switch on the pot the power blinked and the TV died. I went out and checked fearing a major defect and then realized I had shut off the fuel. I blamed it on the early morning and lack of caffeine!

I will say the EU 3000 seems a little cold natured. I guess it is just running very lean with no choke.

 

[DMerryman]

Genarac 4000 XL & Ear Plugs

Well gents,. .

I have a friend that has a Generac 4000 XL that uses it for various work around his property. I thought that maybe I could slide by and find something that will power my 13,500 Btu A/C unit in my 5'er. Generac claims it is a quieter unit with the Over-Head Valve set-up. I had him start it up for me. The 4000 XL appeared to sound louder than my lawn mower. And I'll tell you, you don't want "MY" lawn mower!! At idle this unit was bearable, but as soon as load is applied, get out your ear-plugs. Home Depot in my area was selling the 4000 XLI for $749. Included was the Electric start, wheel kit and various plug adaptors, 12v charging kit, 6500 start-up wattage.



I originally wanted a Honda Eu2000i, but it appears that this unit may be marginal to unacceptable for wattage/start up wattage/amps. But a great unit for noise control, db rating and is very light weight. This unit selling for $884 from Southwest Fasteners in Lake Havasu, AZ. They have a web site and had a friend verify they are legitimate outfit. FREE shipping in the US of A. http://www.southwestfastener.com/productsIndex.htm



Generac 4000 XL has the wattage/amp's, but I'm not parking next to some of you folks with it. I'll never get offered a cold one from ya, let alone the back of the head slapping I'll get from the wife!



I am now on the hunt for a test run on the Honda Eu3000i. The hunt goes on. Anyone with Eu3000i experiences, I would like to hear from you.



Light weight units are probably out of the question now. Can't have everything. So it's to the drawing board for loading and unloading the unit from my truck.



Thanks again gents, I'll post my findings.



Doug M.

 

[Mingoglia]

I have a 4kw Onan (only Cummins for me) Emerald Plus. I run a 13,500 and a 7,100 BTU A/C at the same time. When I need both A/C units, it's over 100 degrees outside (I live in Phoenix and if I go to the lake on the weekend, I can only sleep if I can get the front bedroom *cold*). When both A/C units are running, I usually also have a pretty big stand up fan running at the same time as well as the 27" TV (afterall we're camping aren't we?) and the sattelite going. I also have the normal stuff running like the power converter and the refrigerator (I always leave the refrigerator in the 'auto' position) This setup works well. I always turn on the bigger A/C unit first and the generator barely changes tone when everything is turned on.



Before I bough my rig, I spent a couple of days on the phone with Dometic getting all the figures for startup amps, running amps, etc. Since my rig is a '02 model the newer higher efficiency models were getting popular. Although the "high efficiency" sounds like what I needed it turned out to be the opposite. When comparing the numbers, these units pulled considerably more when they first started up but pulled considerably less once they were running. Since I was already pushing the limits with my startup amps, there's no way I would of been able to run one of these units (due to startup amps) and ended up purchasing two of the normal A/C units.

 

[tgrfan2]

EU 3000 is

I searched for months to try to get the best generator for my needs. I had been using a Honda EM 5000 with my camper. It did the job well, but still was noisy. We tailgate with a lot of motorhomes and it is bad to be too loud. My final choices were the 4000 watt Onan or the Honda inverters. I decided on the Honda because of weight and price.

I bought the 3000 because I was afraid the 2000 in parallel would not run a larger camper with 50 amp service. The 3000 does fine with my 13500 btu AC as long as I start it first and don't let it cycle. It will even pull the AC, frig and 1000 watt microwave at the same time after the AC starts.

The other thing I like about it is it will run all night pulling the AC or ceramic heater. The 2000 has too little fuel capacity.

If I need more capacity later, I can buy two 3000's for a little more than the Onan was installed and they are much more flexible.

The amazing thing with the 3000 at our last tailgating was that I thought I was hearing my generator located on my "back porch" and instead was hearing a motorhome parked next to me.