I'm converting a cargo trailer into a camper. Over the weekend, I tried to install an AC unit. The unit that I bought requires 8.8 amperes at 115 volts. My inverter is an 1800 watt trip lite that I have had installed in my truck for several years. I've used the inverter to run power tools, electric kettles, and other high current loads, so I'm pretty sure it works fine, and should support 15 amperes without difficulty. When I try to run my AC unit though, it runs the fan for 3 minutes, the compressor never comes on, and then the inverter shuts down. I monitored my 12 volt supply while doing this, and it never even flickered, 13.5 to 14 volts the whole time (engine running) I took the AC unit into the house to see if it would run from a mains outlet, and it does.So...If there's nothing wrong with the AC unit, nothing wrong with the inverter, and nothing wrong with the low voltage supply to the inverter, what could be the problem?

Run your a/c on shore power or generator (large enough to handle it).

Robert Kesselring wrote:If there's nothing wrong with the AC unit, nothing wrong with the inverter, and nothing wrong with the low voltage supply to the inverter, what could be the problem?The inverter and supply powering it just doesn't have the capacity to deal with the A/C's LRA (Locked Rotor Amp) rating which will be many times it's running amps. As an example it's not uncommon that a typical roof mount 13,500 BTU A/C would have an LRA of 60+ amps even though it's total running amps may be well under 15 smps. Just because you have a smaller A/C doesn't mean it's exempt from this sudden high current demand that is overwhelming your inverter. Equipping the A/C with a Micro-Air Easy Start soft starter kit would likely solve this issue.

SoundGuy wrote:a Micro-Air Easy Start soft starter kit would likely solve this issue.Those things are not cheap!!What I'm finding when I google that looks like about $300. For not a lot more, I could upgrade to a larger inverter.The 1800 watt unit that I have is supposed to support a peak of 3600 watts for starting motors, just like you're talking about. 3600 watts should be about 30 amperes. How much do I need to start a 9 amp motor?Wouldn't a spike in draw cause a momentary dip in the low voltage supply, at least until the inverter cut off. I'm not seeing any dip at all. Even setting my volt meter to record max and min voltage, its, recording a min that's still 13+ volts, and it's watching on millisecond time scales.

Classic case of startup amps being too much.As someone mentioned, it may take 40-60amps to get going and the unit just can't put that out.

Robert Kesselring wrote:SoundGuy wrote:a Micro-Air Easy Start soft starter kit would likely solve this issue.Those things are not cheap!!What I'm finding when I google that looks like about $300. For not a lot more, I could upgrade to a larger inverter.The 1800 watt unit that I have is supposed to support a peak of 3600 watts for starting motors, just like you're talking about. 3600 watts should be about 30 amperes. How much do I need to start a 9 amp motor?Wouldn't a spike in draw cause a momentary dip in the low voltage supply, at least until the inverter cut off. I'm not seeing any dip at all. Even setting my volt meter to record max and min voltage, its, recording a min that's still 13+ volts, and it's watching on millisecond time scales. Even “if” you get an inverter large enough to run the ac, it would require a “very” large battery bank to make a sustained run. I haven’t “crunched” the numbers....but, it would require many typical batteries!

Having problems running AC from inverter. | Good Sam Community

pianotuna
Nomad III
Aug 27, 2018
johndeerefarmer,

The eu2000 has a continuous rating of 1600 va--far less than that of a 20 amp shore power supply.

The eu2200 is a bit better at 1800 watts continuous, but again less than a 20 amp shore power supply.
johndeerefarmer
Explorer III
Aug 27, 2018
You have several choices:
1. Get the Microair Easy Start. With mine I can run my 15k ac from a 120VAC 20A outlet when I am plugged in at my driveway.
2. Get a generator. The Honda EU2000 or newer 2200 is even better. You still might need the Easy Start so you are just as well to do #1 first.
3. Sweat..............
pianotuna
Nomad III
Aug 22, 2018
Hi,

There is sort of an exception to that. The Yamaha 3000 sIEB does do a ten second "boost" from the starter battery on the generator. But, of course, it has to be running to do so.

Optimistic Paranoid wrote:
No. No inverter generator is set up to accept current from an outside dc source.
pianotuna
Nomad III
Aug 22, 2018
1. open frame is not electric start
2. open frame is not remote electric start
3. open frame may use more fuel under low loads
4. open frame is NOISY
5. open frame may have a poor wave form
Robert Kesselring wrote:

This is probably a dumb question, but what's the difference between the inverter generator that you mention...
Champion 3400w inverter/generator

and the equivalent output generator?
Champion 3500w generator

The latter is less than half the price. What does the former do for me to justify the extra $470?
time2roll
Nomad
Aug 22, 2018
Robert Kesselring wrote:
So the inverter generator makes DC, then uses an inverter to convert to AC? If that's how it works, is it possible to tie a battery bank into the DC side and use it like a regular inverter when I want it to be quiet. (I.E. to run AC at night)

Not going to work that way. You have an inverter that is lacking battery power and the proper wire to feed the necessary amps to make it work. Same issue would exist with any inverter.

"In an inverter generator, the core uses
multiple coils and multiple magnets. Each
full rotation of the engine produces more
than 300 three phase ac sine waves at frequencies
up to 20 kHz, which produces
more electrical energy per engine revolution.
A microprocessor-controlled inverter
module converts the high-frequency ac to
dc (about 200 V in at least one unit) before
“inverting” it back to clean, stable 120 V,
60-Hz ac power. "

http://www.arrl.org/files/file/QST%20Binaries/QS0608Kleinschmidt.pdf

If you really want quiet A/C all night then find yourself some hookups.
Going solar/battery/inverter to run the A/C 24/7 is going to be a large $10,000+ project and may not even be very portable.
SoundGuy
Explorer
Aug 22, 2018
Robert Kesselring wrote:
So the inverter generator makes DC, then uses an inverter to convert to AC? If that's how it works, is it possible to tie a battery bank into the DC side and use it like a regular inverter when I want it to be quiet. (I.E. to run AC at night)

Most of these inverter gensets will have a DC charging output of limited capacity, IIRC ~ 8 amps in the case of this particular Champ, BUT it's unregulated and simply isn't capable of providing the amount of surge current your A/C requires on start up. Regardless, even if you could do this how would that solve your problem when the genset still has to be running in order to provide this output. :h The simple reality is that 'though technically possible your plan to power your A/C with an inverter just isn't practical - as I said earlier if it was we'd all be doing it. :R
Optimistic_Para
Explorer
Aug 22, 2018
No. No inverter generator is set up to accept current from an outside dc source.
Robert_Kesselri
Explorer
Aug 22, 2018
So the inverter generator makes DC, then uses an inverter to convert to AC? If that's how it works, is it possible to tie a battery bank into the DC side and use it like a regular inverter when I want it to be quiet. (I.E. to run AC at night)
TexasRangerRzR
Explorer
Aug 22, 2018
The more expensive one is much quieter. An inverter generator doesn't have to run at 3600 rpm constantly to provide 60 hz electricity, but the other one (open frame or contractor generator) does no matter the load.

Unless you are all by yourself on BLM land, your neighbors won't appreciate you running the cheaper one anywhere near them.
SoundGuy
Explorer
Aug 22, 2018
pianotuna wrote:
My choice for a genny would be the Champion 3400 watt inverter/generator

Robert Kesselring wrote:
What does the former do for me to justify the extra $470?

The inverter model is dramatically quieter, even when running full tilt. The latter runs full speed constantly and isn't suitable for use anywhere anyone else may be nearby. The cost difference of just $470 is a mere pittance for a genset you can operate in the presence of others, 'though some would still argue they don't want to be anywhere near any genset no matter how "quiet" it supposedly may be.