two Honda eu2000 not starting A/C

2oldman wrote:
Thanks.

Desert Captain wrote:
When the AC kicks back on creating the heavier load the Honda's are free to throttle back up unlike when they are locked into the ecco mode.

This is the part that confuses me, and I said earlier that my Hondas act in just the opposite fashion.

I don't understand what 'throttle back up' means when you say "unlike when they are locked into the eco mode." When eco mode senses a heavy load, they're perfectly free to throttle up. However, in the case of air, the load is TOO heavy and sudden.

Since nobody else is questioning this (well, I did get one X2), I guess it's just me who's not following this.

It's really quite simple, once you know how motors and generators work. But this is not something most people learn.

In Eco mode, rpm is down to idle. To get just full rated power, the genset has to throttle up to full RPM, accelerate its own mass. The 100% or greater overload from trying to start an electric motor happens too quickly, the genset disconnects to protect itself.

Out of Eco mode, the genset is running at full power RPM, but light throttle, so it is not producing full power. To produce full power it need only increase fuel and air flow, it does not need to accelerate. Again though, you are suddenly asking for a surge of overload power. This gets produced by briefly bogging down the rotor a little bit, changing some of that mechanical energy of rotation into a brief surge of power, in excess of rated power.

The generator can produce a surge because when the rotor is slowed, back EMF is reduced, internal impedance is reduced, you get more current briefly. This helps fill the gap as the genset throttles up to match the load.

What happens with current, rotational speed, impedance, back EMF inside a generator or alternator is the opposite of what happens inside the motor when you are trying to start it from a standstill, or if you suddenly increase the load on an idling motor.

The value of that rotational energy for smoothly handling sudden load changes is so important that we will accept the 7 to 15% efficiency losses inherent in motor-generator sets to smooth out power supply to loads that are subject to surging (like big motors) or sensitive to surges in external supplies (like expensive electronics).

Put your Honda in Eco mode, RPM is down too low, there is no mechanical energy to produce a power surge to handle your load surge.

You don't have to believe me, you can pick up a book on electric motor theory from an engineering library. The one I learned from was written in the 1930s; the engineering technology is even older, worked out in the late 19th century when Edison and Westinghouse were learning how to build stable power supplies for factories and cities.