Motor genarator ratio

[turbogt16v]

hello..

I need some information from someone that knows,not someone that think he knows.
What is ratio of lost current in best moderate conditions from motor to generator.

[TinselKoala]

For motors, efficiency is defined as the ratio of input electrical power to usable shaft mechanical output power.
The best small motors (under one kW) have efficiencies on the order of 70-80 percent. For large (multi-kW) motors the best efficiency can be as great as 96 percent.
https://en.wikipedia.org/wiki/Premium_efficiency

For generators, efficiency is defined as the ratio of shaft mechanical input power to usable electrical output power. The best electrical generators have efficiencies as high as 98 percent.
http://www.mpoweruk.com/energy_efficiency.htm

When you connect a motor to a generator, the efficiencies multiply. So in the best case you have 0.96 x 0.98 = about 0.94, or 94 percent efficiency. In other words... you cannot make a "Mo-Gen" that will run itself, especially not with power left over. Gearing, belts and pulleys, etc. subtract from this maximum efficiency by adding drag and friction.

Flywheels are energy _storage_ devices and a heavy flywheel, spinning rapidly, can store a lot of energy, but the energy  has to come from somewhere to spin up the flywheel in the first place, and you get back only what you put in, minus losses. (bearing friction, windage, etc.)

[Johan_1955]

For motors, efficiency is defined as the ratio of input electrical power to usable shaft mechanical output power.
The best small motors (under one kW) have efficiencies on the order of 70-80 percent. For large (multi-kW) motors the best efficiency can be as great as 96 percent.
https://en.wikipedia.org/wiki/Premium_efficiency

For generators, efficiency is defined as the ratio of shaft mechanical input power to usable electrical output power. The best electrical generators have efficiencies as high as 98 percent.
http://www.mpoweruk.com/energy_efficiency.htm

When you connect a motor to a generator, the efficiencies multiply. So in the best case you have 0.96 x 0.98 = about 0.94, or 94 percent efficiency. In other words... you cannot make a "Mo-Gen" that will run itself, especially not with power left over. Gearing, belts and pulleys, etc. subtract from this maximum efficiency by adding drag and friction.

Flywheels are energy _storage_ devices and a heavy flywheel, spinning rapidly, can store a lot of energy, but the energy  has to come from somewhere to spin up the flywheel in the first place, and you get back only what you put in, minus losses. (bearing friction, windage, etc.)

Above all true, expand you're thinking with these type's of Coil / Brush Rotor: http://www.wincogen.com/HowGeneratorsWork

[turbogt16v]

first of all ,thank you for really good answer,
second

Flywheels are energy _storage_ devices and a heavy flywheel, spinning rapidly, can store a lot of energy, but the energy  has to come from somewhere to spin up the flywheel in the first place, and you get back only what you put in, minus losses. (bearing friction, windage, etc.)

are you saying that if the flywheel is already in full spin we would get extra power