Yamaha Inverter NPS-6500 Struggling

[The Village Idiot]

If memory serves me correctly, the Yamaha generator in my 2024 Seismic toy hauler is an NPS-6500. I can start it up and it runs just fine any day of the week.

But no matter what I've tried, it falls on it's face more than half the time when I try to start one AC unit. Many times the AC will kick on but the generator can't power up fast enough for the AC to successfully continue. The AC will kick on and the Yamaha will start to rev up but it's as if the revving up just won't cut it before the AC shuts back down and the generator goes to idle speed. If I do manage to get the AC running, I can try to start a second unit and almost always, both ACs shut down and the Yamaha goes back to idle speed.

Any ideas? Am I missing a step? Back in the good old days of my Cummins Onans, it didn't make a difference. One or two ACs would start and run all day long with zero problems. I know the Yamahas are good units but I miss the Onans.

 

[Mark_K5LXP]

Inverter gensets are pretty sensitive to transient currents. A/C startup current can be 3x running, so an example 15KBtu rooftop unit can pull upwards of 40 amps. That should be within the limits of a 6.5K genset you would think. So either the genset is ultra sensitive or the A/C unit(s) are having issues. My take on it would be to put a clamp-on ammeter on the compressor when on mains power and see if they're in spec. From there the function of the genset can be explored.

Mark B.
Albuquerque, NM

 

[Gary RV_Wizard]

It could be what Mark said, the generator overloads before getting up to speed. The NPS 6000 is rated for a max of 6000 watts and a steady 5400 (45.8 amps @ 120v), but it throttles back under light load and needs a few seconds to get up to full output. If it has an "Eco" fuel consumption mode, turn that off and it may be able to react better. Another trick is to increase the load on the generator before starting the a/c. Another 500-700 watts of pre-load may get the generator speed ramped up so that it can handle the a/c load when it comes.

And your a/c units may be drawing a bit heavy too. Maybe even a poor 120v connection somewhere.

 

[CharlesinGA]

Do these generators have a setting for full speed all the time, vs idling and only ramping up under loads? I know most portable units do, but dont know anything about these.

OK, looked at the instructions for a 6000. Nothing about the idle vs full speed running.

Time to call them.

NPS offers full support for service, warranty and technical assistance throughwww.NPSrvpower.com or 1-866-407-1727 during normal business hours (9:00 am-5:00pm(MST)) if assistance is requested outside normal business hours, leave a message or send anemail and a team member will assist you as soon as possible.

Charles

 

[Kirk]

And your a/c units may be drawing a bit heavy too.

I wonder if a "soft start" for the air conditioner might help?

 

[Gary RV_Wizard]

Might. Worth a try.

 

[The Village Idiot]

Do these generators have a setting for full speed all the time, vs idling and only ramping up under loads? I know most portable units do, but dont know anything about these.

OK, looked at the instructions for a 6000. Nothing about the idle vs full speed running.

Time to call them.

NPS offers full support for service, warranty and technical assistance throughwww.NPSrvpower.com or 1-866-407-1727 during normal business hours (9:00 am-5:00pm(MST)) if assistance is requested outside normal business hours, leave a message or send anemail and a team member will assist you as soon as possible.

Charles

I'll most likely call them. Thanks