2KW generator running A/C

[fastrak100]

So I have a nice little Honda i2000 (the one that will work in parallel to produce 4kW.
I have a standard 15000 BTU A/C. Though I realize that is the equivalent to 4.4kW I tried before I bought and if I turned everything off in the trailer the Honda would run the A/C on the A/C's low power setting. Great!
But that was in Florida with the temperature in the 80's
When we got to Death Valley and the temperature hit 100 (it was November, so not over the top heat) I attempted to use the generator to keep cool. It worked happily for about 10 minutes, then you could hear the generator revs rise and the A/C motor slow. Then the generator cut out (too much current being drawn). I was not too surprised when I thought about it, but if you whizz kids have a way to use the i2000 to run A/C I would be really interested to hear the details.

 

[Molaker]

The only way I know of is to get another i2000 and run parallel or get a larger generator.  The "success" you had running the A/C in Fla. was probably because the cycle time was long enough to bleed down the compressor pressure before it would kick in again.  In the higher heat, the A/C will cycle more often as the room temp warms up quicker.  The fast cycling can have the generator fighting residual pressure in the compressor requiring more current to overcome when starting up.

 

[carson]

Good thinking, Molaker.  I guess one way to circumvent that would be to manually turn it off at the thermostat after it quits,  wait a while (5-10 minutes ?)  and then manually restart it it, when in the desert.

 

[jje1960]

Yes, Molaker is correct.  If the generator ran the unit, the restart is what caused the insurmountable amp draw.  One possible solution would be adding a large capacitor, we did and it really helps on the restart.  Or, you can just leave it low enough to continue on the first start cycle, then manually raise / lower the thermostat waiting enough time for the compressor to equalize.  At any rate, adding a Supra capacitor will help when running on inverter/generator, very cheap and easy install.

 

[dave61]

I think you are asking for trouble with that combo. I have the same equipment as you but the only way I would run my 15,000 btu A/C with the Honda 2000 would be to pair it with the 2000 companion.

 

[Bill B]

Fast - from the other post - I'll start out with what I have. Remember that my rig is NOT normal.

I have 4 of these batteries in the coach - 8D - http://www.trojanbattery.com/product/8d-agm/ which gives me 800 ah @ a 10 hour rate

The inverter is a Victron Quattro - 3kw unit - http://www.victronenergy.com/upload/documents/Datasheet-Quattro-3-5-kVA-120V-EN.pdf that allows parallel operation with other units at the 120 volt level. So this provides the start power required and goes back to charging when the A/C or other power units are running. Using the Honda, we have run the A/C, hit the microwave or coffee pot all at the same time. Watching the inverter flip to charge, load, charge as necessary.

Generator is the normal Honda EU2000i. I ought it before they came out with the companion, but would not pay $150 extra for one anyway.

Solar - there is 6 135-watt solar panels on the roof feeding into a Outback Flexmate 80 MPPT charge controller - http://www.outbackpower.com/outback-products/charge-controllers/item/flexmax-80?category_id=438

Plus the hard start kit for the A/C

interesting paper for some "light" reading ---- http://www.victronenergy.com/upload/documents/White-paper-Achieving-the-impossible-EN.pdf

http://www.victronenergy.com/upload/documents/White_paper_Using_the_Phoenix_MultiPlus_to_reduce_operating_cost_of_a_generator_EN.pdf

LOL - like I said - mine is NOT typical

 

[kjansen]

All of the above replies are correct.  IMO, you have a couple of choices.  Add the 2nd generator or install an inverter / battery system to run the AC and the Honda to charge the batteries.  Just make sure your inverter is large enough(3000 watt).

 

[Larry N.]

Just make sure your inverter is large enough(3000 watt).

You'll need a LOT of battery, too, if you want to run it more than a few minutes.

 

[Ernie n Tara]

Note that inverters run on 12Vdc and a 3, 000 W inverter will pull around 300 A at full output (200A at 2, 000 W output). Even large converters only put out about 100 A dc. This means that you will have to pair the inverter with the generator as if it were another generator (so the ac outputs are in phase). You then face the problem of limiting the inverter output so the air conditioner runs primarily on the generator. I strongly favor the idea of buying another generator!!!

If any of the above doesn't make sense to you, then you definitely should go with the generator (or try the larger starting capacitor).

Ernie

 

[Molaker]

If any of the above doesn't make sense to you, then you definitely should go with the generator (or try the larger starting capacitor).

I'm still trying to wrap my head around just how a larger start capacitor would help - unless the original capacitor is spec'd too small in the first place.

 

[Lou Schneider]

A hard start kit consists of the capacitor and a relay that returns the capacitance to the stock value after a couple of seconds.

Changing the capacitance reduces the compressor motor's torque and reduces the amplitude of the locked rotor current spike.  Instead of generating a lot of torque and causing a sharp current spike at startup, the kit reduces the starting torque for a couple of seconds.  There's enough torque to get the armature turning, but not enough to drive the compressor at full speed.  After a second or two the relay drops out and restores the stock capacitance, restoring the motor's torque and letting it accelerate to it's running speed.

 

[fastrak100]

Well I am fascinated so far. I like the idea of a hard start kit, because it is an instant solution and its cheap. However, I don't think it will solve the problem. I love the Victroenergy solution, but a bit to pricy for my situation. Thanks to you people for giving me directions to research, I must admit that looking at the problem in detail it would seem that there are several possible reasons.

1. The higher ambient external temperature may have led to the high pressure side not being able to dissipate enough heat, so that positive thermal feedback kept the pump working harder and harder as higher pressure should enable it to dissipate more heat, until it tripped out (don't think that is the reason).

2. Insufficient current from the gen. did not enable the pump to operate efficiently and get the coolant up to pressure (don't think that is it either).

3. Lower voltage causes the current demand to increase (YES), and the efficiency of the compressor to decrease. Drawing more current increases the inductance in the fan coils, pulling yet more current, but getting slower and slower. Where upon the gen. increased in revs until it hit its trip.

Probably a combination of all three, as in lowish temperatures the increase in current may not be enough to trip the gen., so it works OK in Florida, but once the external temp went up the pump demanded more current to work, which meant the fan motor started to demand more and go slower and Poomph! My own little brown out.
Or something!
So guys, what about a swamp cooler?
Though I would love to find a nice 2nd hand Honda 2kW.
The cheapest solution maybe that we just sit in the truck for an hour or two when it gets really hot.

 

[jje1960]

I'm still trying to wrap my head around just how a larger start capacitor would help - unless the original capacitor is spec'd too small in the first place.

Very easy to install, plenty of youtube and other install and explanation info available.

http://www.loveyourrv.com/installing-hard-start-capacitor-into-my-rv-air-conditioner/

 

[mdbass]

So far nothing on the damage it can do to the a/c unit. Just saying!

 

[Bill B]

One of the things that you guys are missing is - the inverter and the generator are running in parallel. Both are supplying 120 AC to the A/C. So you have 1600 watts coming from the genny and the rest (for starting, incidental loads, coming from the inverter.

So, say the A/C runs with 10 amps (1200 watts). BUT, it needs 3000 watts to start and get to speed, before dropping back to the 1200 watt level. This usually takes about 10 seconds or so. The inverter supplies the rest of the power for that time. Then as the power requirement backs off, it uses the "leftover" power from the generator to recharge the batteries.

That 10 second time frame is also when the hard start caps come into play and reduce the "starting load" of the compressor.


Swamp cooler - great in the desert or other low humidity areas. It cools by using the heat of vaporization to drop the temp.

 

[Ned]

The generator and inverter outputs should NEVER be run in parallel.  That's a sure way to damage or destroy one or both of them.

 

[John From Detroit]

Very easy to install, plenty of youtube and other install and explanation info available.

http://www.loveyourrv.com/installing-hard-start-capacitor-into-my-rv-air-conditioner/

I do not know if it is bigger or not but .. There are many factors that go into the OEM choice.. One is efficency, the government penalizes companies that do not meet energy conservation standards.. The faster you start a motor, the less power (overall) it uses.. HOWEVER the higher the peak power.

That would be my primary guess.. Cost may also be a factor.  It may be the "Standard" part is 1 cent less.

 

[Bill B]

The generator and inverter outputs should NEVER be run in parallel.  That's a sure way to damage or destroy one or both of them.

Ned - I'll agree with you on a 99% basis. For a standard inverter and an engine driven generator (non- inverter genny - not the Honda I-series, Yamaha I series) you are correct.

But, there is a whole different class of inverters out there that will parallel with the electrical grid - designed for it, and do it daily. All the photocell grid and small wind power runs off of parallel inverters. Think for a moment on how the Honda EUxxxxi series work. (You can parallel them also). The first generator that is running establishes a 120 v - 60 hertz output. The second one, when you start it, senses that output, and synchronies to it, and then starts generating with it.

My inverter does the same thing but carries it several steps further. You set the power output of the generator and it automatically adds power @ 120 VAC if needed or recharges the battery if there is an excess available. or the 120v line voltage.

But, I don't think that you read the links that I also posted in #7? My Inverter is designed to run with limited shore power, inverter generators, or other inverters, etc.

As I said, my equipment is NOT the typical electrical stuff.

EDIT: I got kicked in the middle of typing this and before I was finished, so if some of the references to it seem out of context, they are. Just saying.

 

[jje1960]

Think I should clarify my previous... Pictures posted are just for example of the hard start oem capacitor option.  Specific capacitor would need to be ordered for the intended unit.  I installed the capacitor that was appropriate for our unit, noticeable difference in easier compressor starting/restarting.  The capacitor assist was the only part of this situation that I was addressing.  Also, I've spoken to multiple airconditoning techs, they all applauded the capacitor add for easier starting, especially on older units, however stating it's a smart, safe and normal addition for any unit.  Hope this helps any that are interested.

 

[Ned]

Ned - I'll agree with you on a 99% basis. For a standard inverter and an engine driven generator (non- inverter genny - not the Honda I-series, Yamaha I series) you are correct.

But, there is a whole different class of inverters out there that will parallel with the electrical grid - designed for it, and do it daily. All the photocell grid and small wind power runs off of parallel inverters. Think for a moment on how the Honda EUxxxxi series work. (You can parallel them also). The first (

But, I don't think that you read the links that I also posted in #7? My Inverter is designed to run with -- limited shore power, inverter generators, other inverters, etc.

Those inverters are not found in most RVs, certainly not a factory installed inverter.  Anyone reading that statement and not knowing the need for a special type of inverter could get into serious trouble trying to parallel the inverter output with any other source of 120VAC.