3000W Chinese Gensets Info.
professor95 wrote: EDIT ADDED 45/5/2013- When this thread started in March of 2005, I never expected to see it survive this long or amass the quantity of information that has been shared here. In...
Forum Discussion
Nancy and I got back home a little after 2:00 this afternoon. The weather at Virginia Beach was not what we hoped for, but it was still great to be out campin’ again. We had more than our fair share of problems with the new Regal, all attributable to shoddy workmanship or poor materials. I may start a new thread on that subject…..
I just finished looking through the new postings on the forum since I left last Wednesday. There was one item that caused me a little concern, and another that I feel needs to be revisited. I would like to address both of them, if I may.
I still have not seen this unit, but IMHO, using brushes in a modern AC generator (read alternator) is a major concern! “Brushless” alternators were to the AC generator market what the microwave oven was to the TV dinner market. Brushes (or slip rings with brushes) were always problematic. They were the “hot” spot in the generator, often failing under higher current demands. They would wear, they would arc, the sparks caused RFI, not to mention dangerous conditions around gasoline vapors. Going to “brushless” designs improved efficiency, lowered generator head temperatures, reduced electrical interference, and dropped maintenance cost while drastically improving life expectancy.
I sincerely hope the spec sheet for the Champion is in error.
An electric motor that “consumes” 746 watts (corrected from 741 watts 4/4/05) of energy will produce 1 horse power.
While I have been unable to find a true reverse corollary, knowing that if we produce 1 horse power from a gasoline engine and spin the shaft of an alternator to make electricity, we will have losses between the two due to mechanical friction and electrical resistance. Noting the significant heat produced at an alternator’s head, I believe this loss to be considerable - perhaps as much as 30%. Assuming my guesstimate is somewhat accurate (and I believe it is), let’s say it takes 1 horse power to produce 525 watts of power. Multiply that by 5.5 and we come up with 2,888 watts. My experience tells me this is a “reasonable” expectation that coincides with what I have seen in the industry. When literature suggests that we can get 3,500 watts from a 5.5 hp engine, I become suspicious. This translates to 636 watts per horsepower. We must have some gawd awful efficiency going on here! I’m from the old school. When someone tells me something that sounds too good to be true, it usually isn’t true.
I want to repeat a single all important concept when it comes to generators, watts, amps volts, horsepower and all that good stuff discussed on this forum: We are focusing on inexpensive Chinese manufactured generators that will power a Recreational Vehicle with a minimum of noise and be EPA and NPS approved. Industry standards dictate that RV's will "commonly" have a single phase, 120 volt, 30 ampere power cord internally protected by a 30 amp, 120 volt single pole circuit breaker. (I don’t want to discuss all the differences of 50 amp RV’s here).
The RV with a 30 amp power cord does not need or use 220-240 volts. This type of RV uses a single power cord; it cannot split its 30 amp power cord into separate circuits before the breaker panel in the RV. Consequently, everything in the RV must run off of one 120 volt circuit.
Therefore, the generator selected to power an RV must meet these requirements without exception if it is to be satisfactory.
We have discovered that some of the so called 3,500 watt generators will provide only ½ their rated load at 120 volts. This translates to 1,750 watts (or less - often MUCH less) from a single 120 volt outlet. The PEP BOYS Nikota was one such unit. There are others just like it out there! You do not have multiple power cords on a RV to plug into multiple outlets to distribute the load. Therefore, the 3,500 watt rating is worthless for an RV. (It may be great for a home back-up generator or at a construction site.)
RV’s need a generator that will provide their full rated power to a SINGLE 120 volt outlet.
RV’s need a minimum of 20 amps at 110-120 volts (2,400 watts) to even begin to think about satisfactorily powering just a 13,500 BTU air conditioner – not to mention a microwave, the converter or an absorption refrigerator operating on electricity.
Please, please, please, DO NOT allow yourself to be duped by inflated, inappropriate or just plain old wrong performance claims for generators to be used on an RV!
You know.... After all that I just wrote.... I want everyone to know I am no expert on Chinese generators, or any generators for that matter. I am just a tired old college professor who likes to mess with RVs and camp. But, my background in electricity/electronics allows me to form opinions and interpret specifications - and my passion for teaching drives me to share them for your consideration.
I also hate to see people taken by obscure or skewed advertising designed to make an item appear better than it really is.
What was it Grandpa said? Something about buyer beware?
I just finished looking through the new postings on the forum since I left last Wednesday. There was one item that caused me a little concern, and another that I feel needs to be revisited. I would like to address both of them, if I may.
Here is a spec sheet Paul Cole from Champion Power Equipment emailed regarding the Champion unit. This generator uses brushes (not a big deal imho).
I still have not seen this unit, but IMHO, using brushes in a modern AC generator (read alternator) is a major concern! “Brushless” alternators were to the AC generator market what the microwave oven was to the TV dinner market. Brushes (or slip rings with brushes) were always problematic. They were the “hot” spot in the generator, often failing under higher current demands. They would wear, they would arc, the sparks caused RFI, not to mention dangerous conditions around gasoline vapors. Going to “brushless” designs improved efficiency, lowered generator head temperatures, reduced electrical interference, and dropped maintenance cost while drastically improving life expectancy.
I sincerely hope the spec sheet for the Champion is in error.
(the Coleman Powermate generator) Motor appears to be a Tecumseh 5.5 hp OHV which seems a bit small for the rating. Should this be in a different thread of "American Generators" ?
An electric motor that “consumes” 746 watts (corrected from 741 watts 4/4/05) of energy will produce 1 horse power.
While I have been unable to find a true reverse corollary, knowing that if we produce 1 horse power from a gasoline engine and spin the shaft of an alternator to make electricity, we will have losses between the two due to mechanical friction and electrical resistance. Noting the significant heat produced at an alternator’s head, I believe this loss to be considerable - perhaps as much as 30%. Assuming my guesstimate is somewhat accurate (and I believe it is), let’s say it takes 1 horse power to produce 525 watts of power. Multiply that by 5.5 and we come up with 2,888 watts. My experience tells me this is a “reasonable” expectation that coincides with what I have seen in the industry. When literature suggests that we can get 3,500 watts from a 5.5 hp engine, I become suspicious. This translates to 636 watts per horsepower. We must have some gawd awful efficiency going on here! I’m from the old school. When someone tells me something that sounds too good to be true, it usually isn’t true.
I want to repeat a single all important concept when it comes to generators, watts, amps volts, horsepower and all that good stuff discussed on this forum: We are focusing on inexpensive Chinese manufactured generators that will power a Recreational Vehicle with a minimum of noise and be EPA and NPS approved. Industry standards dictate that RV's will "commonly" have a single phase, 120 volt, 30 ampere power cord internally protected by a 30 amp, 120 volt single pole circuit breaker. (I don’t want to discuss all the differences of 50 amp RV’s here).
The RV with a 30 amp power cord does not need or use 220-240 volts. This type of RV uses a single power cord; it cannot split its 30 amp power cord into separate circuits before the breaker panel in the RV. Consequently, everything in the RV must run off of one 120 volt circuit.
Therefore, the generator selected to power an RV must meet these requirements without exception if it is to be satisfactory.
We have discovered that some of the so called 3,500 watt generators will provide only ½ their rated load at 120 volts. This translates to 1,750 watts (or less - often MUCH less) from a single 120 volt outlet. The PEP BOYS Nikota was one such unit. There are others just like it out there! You do not have multiple power cords on a RV to plug into multiple outlets to distribute the load. Therefore, the 3,500 watt rating is worthless for an RV. (It may be great for a home back-up generator or at a construction site.)
RV’s need a generator that will provide their full rated power to a SINGLE 120 volt outlet.
RV’s need a minimum of 20 amps at 110-120 volts (2,400 watts) to even begin to think about satisfactorily powering just a 13,500 BTU air conditioner – not to mention a microwave, the converter or an absorption refrigerator operating on electricity.
Please, please, please, DO NOT allow yourself to be duped by inflated, inappropriate or just plain old wrong performance claims for generators to be used on an RV!
You know.... After all that I just wrote.... I want everyone to know I am no expert on Chinese generators, or any generators for that matter. I am just a tired old college professor who likes to mess with RVs and camp. But, my background in electricity/electronics allows me to form opinions and interpret specifications - and my passion for teaching drives me to share them for your consideration.
I also hate to see people taken by obscure or skewed advertising designed to make an item appear better than it really is.
What was it Grandpa said? Something about buyer beware?
