New England Ice Storm - 8 days with no power here !!!

[WB2YGF]

Good deal Steve.
I bet you won't be complaining about electric rates any time soon after feeding the generator.

Yeah, going off grid is a challange, but there is a guy on the RV.net forum with a 34 ft trailer or 5th wheel who has done it:

1442 watts of solar on the roof. 600AH AGM battery bank. Prosine 2kw inverter. 6KVA diesel gen with auto start. 100% off grid since 6-1-03

[Steve - WB3HUZ]

Good to hear you on 160 earlier. BIG SIGNAL!

10 days !!! Finally (just now) got street power back!!!

And, there's another ice storm on the way later in the week

I'll keep the old generator ready to go, I think 

Regards,

Steve

[W4EWH]

Just got back from Home Depot. They have 3 different models 5 to 6 KW and 7 to 8 peak starting. Range in price $500 to $700. One said it could run 13 hours at 1/2 power.

Does that mean it can't run more than 13 hours, or just that it had to be refueled?

Bill W1AC, who is pricing generators for his home and doesn't like surprises.

[The Slab Bacon]

I would figure about 1 HP/ KW so at 12 KW it is almost sleeping along. Consider a Jeep in high gear running 1800 RPM, how far could you drive in an hour.

Frank,
         The old general "rule of thumb" has always been 2hp (at generating speed) is necessary per 1 KW of electrical power generated. so a 5kw generator would need a 10hp engine to run it comfortably. With low speed (1800 rpm or less) you need an engine that makes the required amount of HP at the reduced speed. since most small air cooled engines are rated at 3600 rpm this means that a much higher hp rated engine will be needed in a low speed generator an it has to be capable of producing the required amount of hp an a rpm range way below its mormal peak power curve.

                                                                           The Slab Bacon

[Steve - WB3HUZ]

You would need a rather efficient system to get 1 kW per horsepower since 746 watts equals one horsepower.

[W1RC]

Good to see that Steve's got his power restored but my good friend and NEAR-fest Treasurer Ed Andersonm N1IWV who lives in Greenfield NH is still without commercial power.  To make matters worse we just had the second 12"+ snowfall in three days.  Ed says he doesn't expect his power to be restored until after Xmas at the earliest.

73,

MrMike

[WA1GFZ]

Steve,
250 watts of heat per KW coming off a generator would have it pretty hot after a while. I bet a generator is quite efficient. Frank, I was thinking the same thing after the post 1800 RPM is pretty slow. And you don't want to run it wide open raped ape.
I don't know what you have to do after 13 hours of running the home chepo generators.

[WA1GFZ]

DUH Huz, I'm inverted 1.3 HP/KW at 100% efficiency

[Ed/KB1HYS]

Just some general Efficiency figures:(these vary widely depending on manufacture and system)

Conversion of mechanical to Electrical (ENG HP to Watts - based on published values for each)  ~80%
Conversion of Energy contained in fuel to Eng HP -  ~25% 
         This varies widely from 20-37% depending on the engine. By far the most inefficient part of the system is the internal combustion engine.  ~30% of the energy contained in the fuel is lost just overcoming the internal friction of the engine. The rest of the loss is going out the exhuast pipe and heat lost through the cylinder walls.

           So at an engine efficiency of 0.25 and a conversion efficiency of 0.8 only about 20% of the energy in the fuel us converted to useful electrical power. 

Recovery of waste heat by using a water cooled engine and exhast gas heat recovery and then having the radiator or heat exchanger heat living space or hot water (or both) would greatly increase overall efficiency, but wouldn't give you any more electric power from the system.

[WA1GFZ]

Yes the engine sucks but the generator alone is very good though. Steve's case the unit is water cooled. Maybe a good idea to run the hot water through some baseboards and heat his shack above the garage.
A couple old cast iron radiators would work great.

[Ed/KB1HYS]

As long as the Gen-set can pump the hot water up to the radiators, and those radiators can hold the pressure required by the cooling system then Go For It, otherwise you'll need to work up a heat exchanger, or remote mount the gen-set radiator inside with an electric floor fan to push the air through.

[WA1GFZ]

Heck add a circulator pump off both ends of the radiator. Radiator pressure is no worse than a baseboard operating pressure.