Yamaha 2000iS and softstart with AC?

The answer to my initial post is clear, I need a more robust (and preferably larger) generator.

I errantly expected that my hybrid inverter (on board, not to be confused with the inverter generator) would just make up the difference between what my AC required and what my underpowered generator would provide. The reality is that the older Yamaha 2K generator can not deal with surge currents (or in-rush, or how ever you want to define motor start up required current), it drops voltage as a response too quickly to play well with the hybrid inverter. Consequently an oscillation is set up between the sources instead of complimenting each other. I momentarily witnessed 400-500A being drawn from my battery bank! Not good for anything in that path including the AC!!!

Prior to starting this thread I’d already discussed the situation with Magnum tech support who suggested (as did otrfun) lowering the VAC dropout to help eliminate the oscillations. Not a solution I’m willing to attempt because of the large current stress that would put on the AC.

Bottom line, my generator is too puny. If it would act like an ideal voltage source just limited to 13A, or 10A or whatever, my hybrid inverter could make up the difference and I’d be happy. The Magnum is very capable of starting and running my AC on it’s own I just don’t want to be drawing 200A from my battery bank for hours instead of minutes. My hopes at a cheap/quick solution (softstart) we’re naive, I just need a bigger generator to run AC. I’m sure that a 2200 Honda would marginally work, but if I’m spending money anyway I’m not going to cheap out on the right solution (like my initial question was pondering…

OP has previously stated that he has a Magnum hybrid inverter - a load sharing type
inverter..,

3 tons

I just posted this chart on another topic...

RV Roof Top Air Conditioners: Watts for start ____Average wattage once running
7000 btu RV air conditioner 1700 ________________________600
10,000 btu RV air conditioner 2000________________________700
13,500 btu RV air conditioner 2750_______________________ 1250
15,000 btu RV air conditioner 3500_______________________ 1500

from https://www.ramsond.com/wattage-chart/

You really need a bigger gen or a smaller AC. IF your trailer is small enough, has small windows and is very well insulated then a 9200 btu would work fine with your 2000 gen. Unlikely you have a 9200 as 13.5 and 15 are most common. If you have a 15 btu then forget it. 13.5 then maybe , but 1,250 watts is more than 50% power just to keep compressor running, thats a lot of load continuously. How long does the compressor normally run per cycle?

Have you tried running your gen on the normal mode? That's not in the eco mode where it idles down when not needed. Run it full speed in non-eco mode and see how much things bog down first. This will tell you if the gen can even supply the power.

For a 13.5btu unit the soft start should work fine if your gen will start it on the non-eco mode. It is that issue of the gen running at idle with almost no power output then having to rev up the motor and bring the power up all while the AC is trying to pull that power out.

If you are handy with electrical then maybe try an additional start capacitor as they are cheap.
If your gen will run the AC then most likely the $320 soft start will start it. Nobody can say unless they have your exact gen and AC combo. Sorry.

*also, Im not really that familiar with the Yamaha. Are you saying that the generator's inverter runs off the coach batteries too? (uses battery power to supply the inverter to invert from DC to AC) The gen puts out AC, then turns it to DC so it can then turn it back to AC through the inverter, which will be able to supply 120 volts no matter the rpm of the generator motor.

If so, then you will need very big and very short battery cables supplying the generator.

These testimonials are fine, but can sometimes be a bit anecdotal depending on one’s own particular situation because there can be many variables…In my case the soft-start didn’t solve my eco-mode engagement problem, and outcomes can vary depending on type of inverter used (i.e. OP’s hybrid type vs non-hybrid pass-thru type, vs NO inverter in the loop), as the generator may or may not not be the actual problem source…Where there’s no inverter in the AC system loop, it’s a far more straight forward proposition, however (if a pass-thru load-sharing type inverter like the OP’s…), I would first try to bypass the inverter to see where the root problem lies…

3 tons

3 tons wrote:
Thinking about this a bit further, I checked the Owners Manual for your Magnum hybrid inverter and for my ProSine 2.0 (non-hybrid) and have come across a better understanding…

On pg 37 of the Magnum manual it talks about “dropout voltage” which is set at factory default of 80vac which is desirable (in many situations) to accommodate the load sharing feature:

“ 3.4 TransferTime
While in Standby mode, the AC input is continually monitored. Whenever AC power falls below the VAC dropout voltage (80 VAC, default setting), the inverter automatically transfers back to Inverter mode with minimum interruption to your appliances—as long as the inverter is turned on. The transfer from Standby mode to Inverter mode occurs in approximately 16 milliseconds. While the MSH3012RV is not designed as a computer UPS system, this transfer time is usually fast enough to hold them up. However, the VAC dropout setting has an effect on the ability of the loads to transfer without resetting. The lower this setting, the longer the effective transfer will be and therefore, the higher the probability for the output loads to reset. This occurs because the incoming AC voltage is allowed to fall to a level that is so low that when the transfer does occur, the voltage on the inverter’s output has already fallen low enough to reset the loads.
The disadvantage of a higher VAC dropout setting is that smaller generators (or large generators with an unstable output) may nuisance transfer. This commonly happens when powering loads that are larger than the generator can handle—causing the generator’s output voltage to constantly fall below the inverter’s input VAC dropout threshold.”

And in my ProSine 2.0 manual the issue of ‘Hysteresis’, pg 89:

“Consider a scenario: the PROsine is operating in charge mode from shorepower. The shorepower voltage falls below the transfer point of 90V. The PROsine transfers to invert mode and the shorepower voltage rises to 95V - but the PROsine does not transfer back to shorepower even though the shorepower voltage is now above the transfer point. In this instance the PROsine applies 10V of "hysteresis" to the transfer voltage before accepting the shorepower again (that is, the PROsine will require 100V on the shorepower before transferring back).”

On my pass-thru type ProSine (non-hybrid), ‘vac’ hysteresis is not user adjustable (though vdc is), and there are user adjustable settings for frequency (from 40 to 70hz) and voltage dropout (85 to 135vac range)…

So, hysteresis can play a role, but it would appear that lowered settings will help facilitate a smoother transition to the eco mode…

I believe that the above issues need to first be considered before opting for a Soft-start…You might try a test by connecting the air cond directly to the generator (bypassing inverter, while in eco mode) and hope for success…

3 tons

The Micro Air Easy Start can dramatically lower the voltage drop that's triggering the transfer in the first place. The Micro Air drops the LRA/inrush current draw of the a/c compressor by as much as 60-70%, which significantly lowers the resultant voltage drop. There's no guarantee the Micro Air will correct the op's problem, but it does *directly* address the problem.

Thinking about this a bit further, I checked the Owners Manual for your Magnum hybrid inverter and for my ProSine 2.0 (non-hybrid) and have come across a better understanding…

On pg 37 of the Magnum manual it talks about “dropout voltage” which is set at factory default of 80vac which is desirable (in many situations) to accommodate the load sharing feature:

“ 3.4 TransferTime
While in Standby mode, the AC input is continually monitored. Whenever AC power falls below the VAC dropout voltage (80 VAC, default setting), the inverter automatically transfers back to Inverter mode with minimum interruption to your appliances—as long as the inverter is turned on. The transfer from Standby mode to Inverter mode occurs in approximately 16 milliseconds. While the MSH3012RV is not designed as a computer UPS system, this transfer time is usually fast enough to hold them up. However, the VAC dropout setting has an effect on the ability of the loads to transfer without resetting. The lower this setting, the longer the effective transfer will be and therefore, the higher the probability for the output loads to reset. This occurs because the incoming AC voltage is allowed to fall to a level that is so low that when the transfer does occur, the voltage on the inverter’s output has already fallen low enough to reset the loads.
The disadvantage of a higher VAC dropout setting is that smaller generators (or large generators with an unstable output) may nuisance transfer. This commonly happens when powering loads that are larger than the generator can handle—causing the generator’s output voltage to constantly fall below the inverter’s input VAC dropout threshold.”

And in my ProSine 2.0 manual the issue of ‘Hysteresis’, pg 89:

“Consider a scenario: the PROsine is operating in charge mode from shorepower. The shorepower voltage falls below the transfer point of 90V. The PROsine transfers to invert mode and the shorepower voltage rises to 95V - but the PROsine does not transfer back to shorepower even though the shorepower voltage is now above the transfer point. In this instance the PROsine applies 10V of "hysteresis" to the transfer voltage before accepting the shorepower again (that is, the PROsine will require 100V on the shorepower before transferring back).”

On my pass-thru type ProSine (non-hybrid), ‘vac’ hysteresis is not user adjustable (though vdc is), and there are user adjustable settings for frequency (from 40 to 70hz) and voltage dropout (85 to 135vac range)…

So, hysteresis can play a role, but it would appear that lowered settings will help facilitate a smoother transition to the eco mode…

I believe that the above issues need to first be considered before opting for a Soft-start…You might try a test by connecting the air cond directly to the generator (bypassing inverter, while in eco mode) and hope for success…

3 tons

MNRon wrote:
Sandia Man and Gdetrailer - thanks for your replies. I don’t have a problem using my battery bank to augment my underpowered generator, my current issue is that the Yamaha 2000iS is so weak that to can’t deal with the surge and puts the system into oscillation. IF I can know the softstart would prevent this I’m good with that solution for the amount of AC we typically require.

With all of that said, I do hear the advice I’m being given and am starting to entertain more seriously. Space and weight (as well as cost) make the Onan solution overkill for our need, but maybe a 3k genny is in my future…

Some food for thought you may find useful before embarking on a larger, new generator.

Not all 2000-2200 watt generators are created equal. The older Yamahas and many 2000w generators are known for their lack of inrush current. Inrush current (less than a second in duration) is needed to start an inductive load like an a/c compressor. The Honda 2000-2200's (which Micro Air highly recommends by the way) have repeatedly shown (in realworld use and testing) they have very high inrush current relative to their 2000-2200 watt continuous rating.

As for surge current, many folks confuse inrush current with surge current. They're very different. Inrush current lasts less than a second (typically rated in ms), whereas generator manufacturers can rate surge current anywhere from a few seconds to 30 minutes (Honda). Huge difference between a few seconds and 30 minutes.

Similar performance differences exist with RV a/c units, too. Not all 13.5 BTU (or 15k BTU) a/c units are created equal. Some 13.5k BTU a/c units can have an LRA (locked rotor amp or inrush current) rating as high as 70a, some can be as low as 50a. In addition, continuous current ratings can also vary widely, too---anywhere from 11a - 15a. Purchasing an efficient 13.5k BTU a/c unit can greatly increase the pool of 2000-2200 watt generators that can successfully start, run it. Installing a Micro Air Easy Start in an efficient 13.5k BTU a/c creates a powerful combination---you'd be hard-pressed to find any 2000-2200 generator that cannot start, run it.

microaire Easy Start ROCKS.

Will you older generator run it, hard to say. I know on a 15k AC, my westinghouse 2500 did fine with ez start

MNRon wrote:
Wanderingaimlessly - I have run my AC off of batteries, but at ~160A when it was hot yesterday it only takes a couple hours to draw my AGMs to 50%…even with 4/0 cables, not sure I want to continually be running that kind of current.

You don't. Things tend to heat up, cables, connectors, batteries. I run a 48v system with 1/4 the amperage and things still heat up.

Yeah. A larger generator won't have to work as hard as that little 2000.