| Author |
Message |
Peter (Sdibaja) (200.38.22.70)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 25, 2003 - 12:01 pm: | |
Is there any reason why I should not run one small generator for the low load times, and fire up a second one for the higher load needs?
AC units don’t take much juice when running, but they need quit a bit to start up. The 5.5 KV Onan we had on our motorhome did the job well and went to a fast idle once the second unit was running. One 4.0 KV will easily start one roof top AC unit, and will also comfortably run both, but has a hard time getting the second unit going.
Several times I have used one of those small portable units (1 KV?) to run power tools, battery chargers, etc. when I am working out in the woods, it works out just fine. Why run a big gun to do a small task? What about firing up a second generator to give the extra juice to start big motors and shut it down after the motor is running?
As we all know, there are tons of used generators available from old RVs. Most are high quality Onans with very little time on them. They are almost free.
I am not a tight wad, but I see no reason to spend a lot on a big generator, or the fuel to run it, if two smaller (economical to buy and run) can be used. |
Geoff (Geoff) (64.1.0.26)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 25, 2003 - 12:29 pm: | |
You can't run two generators on the same line-- they will be out of phase. EXCEPT for the Honda EU series. If youi want to suppliment power to your generator you can install a Trace SW series inverter-- it has the ability to synchronize the AC phase with the genset (or shore power) to suppliment overload conditions.
--Geoff
'82 RTS CA |
Scott Whitney (66.82.9.17)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 25, 2003 - 12:40 pm: | |
Seems that using an inverter to handle all small loads and a generator to handle big loads is the best idea. Much more efficient use of power.
The only way I would consider a two generator set-up would be to have a main AC generator for all normal big loads. Then have a second small DC generator for dedicated battery charging - something in the chainsaw/leafblower size (very well sound insulated) that would sip the fuel and top up the batteries over many hours.
Even still, I am not sure that a large genny connected to a big inverter/charger with short run times would not be more efficient way to charge batteries. . .
Now if someone could design an air conditioner that ran directly on gasoline, propane, kerosine or diesel . . . then maybe a large genset would be a thing of the past . . .
Scott |
Gary Stadler (Boogiethecat) (68.7.217.217)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 25, 2003 - 1:20 pm: | |
Peter, I see no reason why it wouldn't work to have two generators, except that doubling fuel-guzzling mechanical machines usually doubles the hassles associated with them... exhaust pipes, noise, reliability and servicing, etc.
That said, the idea of using two smaller gensets in parallel to start air conditioners is not a good one...because of the way the genset's internal voltage regulators work it's very unlikely that they would share the load properly, not to mention the problem of synchronizing them together...
Personally I installed a 7.5Kw propane onan for times when I need big AC power like A/C's, saws, and the microwave oven (oh yeahm the blender too, to do the marguritas when I'm done) I just turn it on and off as needed...since it's propane it starts immediately. It's no biggie to run small loads on it, and as long as I don't leave it on all day to cook one piece of toast, the efficiencies (or lack thereof) are not even noticable.
Beyond that, all my lighting is 12 volts as is stuff like heaters, blowers, etc. I have a small (300 watt) inverter to run my computer, but that's the only smallish AC load I've got that I don't use the gene for. Unless I'm in the desert running the A/C's, my living style has me turning the gene on maybe once per day for 5 to 10 minutes, and that's about all. The 12 volt house batteries take care of me the rest of the time...even that's only four T105's and they easily take me two weeks between chargings with my living styles.
I guess it all boils down to how often you use AC powered stuff, how often you use lights and how efficient they are (I use fluorescents everywhere, with 12 volt electronic ballasts) and whether or not you have the storage space and patience to blow off with a second genset. "My way" says absoutely no to the mere idea of two of the beasts....
Kind regards
Gary |
j clark (64.12.96.235)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 25, 2003 - 6:19 pm: | |
Been there & like that! I have a kohler 12000 watt main genset that runs everything. I use it mostly for a/c and major charging. I have a 3000 watt inverter with a 1000 amp 6 volt battery bank and 400 watt solar system that provides most of my daily requirements (except in hot weather, which I normally avoid). I added a 2000 watt genset to run my 140 amp charger. I love my sattellite TV, surfing the net at late night, and my wife prefers to use the inverter for doing the morning coffee, (she puts up with me, so I put up with it). I normally run my small generator 30-45 minutes each day to make up the shortfall. I just left Quartzite and the system worked great. I think a hybrid generating system, similiar to the Toyota/Honda automotive setup, will soon become the norm in RV gensets (or fuel cells if cost can be contained) jc |
Bill Keller (209.173.121.57)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 25, 2003 - 9:31 pm: | |
How about running one of the New Honda 2000W gen.
for the small loads like the tv and some lights. If you feel you are depleting your battiers. They
are very quiet and cheap to run, and when you need
more power for the A/C and ect. start the big boy.
Just thinking out loud. Also the honda would come
in handy other times and I believe they have a battery charging capably if you have a dead battiery on the coach or on another vehicle. |
Sean Welsh (Sean) (64.81.73.194)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 25, 2003 - 9:38 pm: | |
Peter,
Geoff is right -- you can't easily run two AC generators in tandem. However, if you get an advanced inverter/charger, such as the Trace SW series, you can size the genset just for the "continuous" load, and let the inverter help with the starting current using it's "load support" capability, as Geoff also suggests. There IS a way to run two small generators in tandem, though, and it is an extension of what Scott suggests: Get yourself a Trace SW serier or similar model with load support capability, hook your AC generator to the AC2 input, and then get a DC generator big enough for your supplemental loads and connect it across the batteries. Your DC generator will need to have an integral charge regulator, or you will need to have an external one between it an the batteries (Trace makes those as well).
That being said, I think, if you run the numbers, that it makes little or no economic sense. You're going to save maybe a quart per hour or so (if even that much) on generator fuel by running the smaller set (vs. a set properly sized for the full load you expect), yet you will have virtually double the maintenance expense (you will end up changing oil, filters, etc. on two sets, and even if you keep the run-time down, you will still need to do it just based on elapsed time). Add that to the expense of two units vs. one larger one, the extra weight you will carry around, etc. etc. and I don't think the math works well. Now, if you were doing this on, say, a remote island someplace, and fuel deliveries were expensive and few and far between, it might make sense.
Just my $0.02
-Sean |
j clark (64.12.96.235)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, January 26, 2003 - 2:25 am: | |
Actually, if you run the numbers, very little of our lifestyle makes economic sense. One of the biggest reasons for switching to a Honda 2000EU for charging my batteries is my big 12.5 kw Kohler was never getting a sufficient load to burn off the contaminants(it was essentialy idling), and diesel fumes are not a good way to greet or meet the neighbors. My Kohler is properly sized for hot weather operations with the a/c's going, but not in cooler weather with very light loads. Oil and filter changes on the Honda runs about $8 bucks versus $25 for the Kohler. I have the Honda in a silencer box (it comes with a 53-58 db rating from the factory) and the neighbors don't even know its running. I actually have opened the box to confirm it was still running. A whisper is about what it equates to. The Honda 2000eu meets the Calif 2008 emission requirements and the inverter output is true sine wave and I always have a backup generator. My neighbors think I run totally on solar power but what the hey- different strokes for different folks and thats what keeps this board so interesting |
Richard Bowyer (Drivingmisslazy) (66.190.119.82)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, January 26, 2003 - 7:45 am: | |
Although your Kohler was running with a light load, it was not idling. The genset must run at 1800 rpm to produce 60 hertz output. At idle, it would not produce any power at all. FWIW
Richard |
J Clark (205.188.209.11)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, January 26, 2003 - 1:03 pm: | |
Sorry about that Richard. I think you know what I meant. I have always associated idling with minimum fuel flow, not with a pre-establised RPM as in 'flight idle' on helicopters. When charging just the batteries, my Kohler throttle lever is against what I call the 'idle' detent' so I called it idling. I will also try to convince my Honda genset and Onans 'quiet genset' that they can no longer operate below 1800 rpm while providing 60 hertz input (its in the windings) Take care! jc |
Michael J (Mjryan) (67.41.226.205)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, January 26, 2003 - 1:26 pm: | |
The Honda EU1000iA2, EU2000i and the EU3000i can produce twice the power if hook in parallel. The noise level is 59dB @ rated load and 53 dB @ 1/4 load for the 1k & 2k. The 3k is 58dB @ rated load and 49 @ 1/4 load. The weight is 29 ,46.3 and 134lb's. They all have inverter technology
(computer friendly) and will run a longgggg time on a tea cup of fuel.
Michael j |
Richard Bowyer (Drivingmisslazy) (66.190.119.82)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, January 26, 2003 - 3:28 pm: | |
You are correct and I ignored this system. Sorry.
I think you may find however that the quiet Onan does not produce 60 hertz power directly. The output of the genset is connected thru an electronic inverter that takes the varying frequency of the genset and then converts it to 60 hertz.
I have built many of these type systems for luxury yachts and control the genset rpm from 1200 rpm to 2100 rpm. The output frequency of the genset varies from approximately 30 hertz to approximately 70 hertz. This varying frequency is converted to DC and then reconstructed as a 60 hertz output by the electronic inverter. Since the output hp of the engine varies with the rpm, I can control the load on the engine by either raising or lowering the rpm so that the engine is always operating at the proper hp for the connected load.
For a true genset output of 60 hertz, a 6 pole alternator operates at 1200 rpm, a 4 pole alternator at 1800 rpm and a 2 pole alternator at 3600 rpm. Any change in the rpm will directly affect the output frequency. Very large alternators are available as 8 pole and 10 pole. These monsters run so slow that you can practically count the rpm by watching the shaft turn. FWIW
Richard
Richard |
J Clark (205.188.209.11)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, January 26, 2003 - 4:48 pm: | |
My Honda EU2000i also uses an inverter system, to produce a 120 volts at 60 cycles, whoops I mean 60 hertz, its hell getting old but why do they have to change the terms on us. I remember back in the '60's, as a test pilot we used 24v inverters that had little dynamo's that had to spin up to 1800 rpm to give us 110v 60 cycles. We have come a long way since then.
The bottom line is that I really enjoy my present setup, but I know it will change. I have been through three coaches and 13 years of almost-full timing and I am finally getting it to just the way I like it. My only regret is that I didn't listen a little closer to some of the 'old timers' recommendations. They had been there and done that and just smiled when I told them what I 'thought' was the best way.
Oh, and by the way, I'm an RVIA tech and a graduate of the Onan school of troubleshooting, and you are absolutely right, the Onan produces 60 hertz at less then 1800, but then again, isn't that where we started.
Watch out for the Columbs and stay away from the sine waves. jc |
Stephen Gutknecht (66.174.34.156)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, January 27, 2003 - 2:43 pm: | |
J Clark - can you please email me at Stephen@RoundSparrow.com
I would love to get details of how you mounted your Honda. We have the exact same setup as you (a Kohler/Yanmar 12.5K + Honda EU2000) but you seem to be 6 steps ahead of us in properly mounting them, etc.
I would even be willing to write some web pages to document your setup. Do you have photos and so forth of your Honda silent compartment?
Thank you.
P.S. I am currently in San Diego, any chance you are near by? I see you mentioned Quartzsite... |
Stephen Gutknecht (Roundsparrow) (66.174.37.99)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, January 28, 2003 - 2:29 pm: | |
J Clark - I still want to reach you, please email.
Basically I'm looking for your experience on:
1. What 140amp charger did you get that will operate off your 13.5 amps the Honda 2000i provides?
2. How did you vent the exhaust on your 2000i? Did you do any special fuel tricks.
3. Did you add some type of remote start, or do ou go back and pull the string?
Thanks. |
|