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Old 05-26-2019, 08:21 PM   #11
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It's simple you just run the output of the generator into an inverter!

In most cases the generator puts out multiphase AC current from an alternator which is converted to DC. This DC current is feed to the generators inverter which converts it back to 120 volts AC @ 60 cycles regardless of generators speed. The inverters microprocessor maintains a solid set voltage at 60 cycles and controls the generators throttle to maintain the constant amperage needed for the load.

Regards- Mike

Yep, but the generator unit is not a standard AC generator as it is generating many (300?) ovelapped sine waves so you can't just slap a rectifier and an inverter on an Onan style generator and have an inverter one. Apparently they need that many phases to smooth out the AC at lower rpms. You need a completely different AC generator section.



Back to what I said originally, the only way Onan can have throttle control is build the generator as an inverter generator. Your statement that all you need to do is add a rectifier and inverter won't do it, I think, or someone would have kit for it. To me if you have to change the generator design, add a rectifier, and add an inverter, and likely have to have a computer controlled throttle to vary the speed, you have just redesigned the generator from a conventional to an inverter style as all you have left is the engine. I know you will disagree with that, but that is certainly the way it appears to be from what I have seen.
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Old 05-26-2019, 08:22 PM   #12
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Quote:
Originally Posted by IdleUp View Post
It's simple you just run the output of the generator into an inverter!

In most cases the generator puts out multiphase AC current from an alternator which is converted to DC. This DC current is feed to the generators inverter which converts it back to 120 volts AC @ 60 cycles regardless of generators speed. The inverters microprocessor maintains a solid set voltage at 60 cycles and controls the generators throttle to maintain the constant amperage needed for the load.

Regards- Mike

Yep, but the generator unit is not a standard AC generator as it is generating many (300?) ovelapped sine waves so you can't just slap a rectifier and an inverter on an Onan style generator and have an inverter one. Apparently they need that many phases to smooth out the AC at lower rpms. You need a completely different AC generator section.



Back to what I said originally, the only way Onan can have throttle control is build the generator as an inverter generator. Your statement that all you need to do is add a rectifier and inverter won't do it, I think, or someone would have kit for it. To me, if you have to change the generator design, add a rectifier, and add an inverter, and likely have to have a computer controlled throttle to vary the speed, you have just redesigned the generator from a conventional to an inverter style as all you have left is the engine. I know you will disagree with that, but that is certainly the way it appears to be from what I have seen.
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Old 05-26-2019, 11:41 PM   #13
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Yep, but the generator unit is not a standard AC generator as it is generating many (300?) ovelapped sine waves so you can't just slap a rectifier and an inverter on an Onan style generator and have an inverter one. Apparently they need that many phases to smooth out the AC at lower rpms. You need a completely different AC generator section.



Back to what I said originally, the only way Onan can have throttle control is build the generator as an inverter generator. Your statement that all you need to do is add a rectifier and inverter won't do it, I think, or someone would have kit for it. To me, if you have to change the generator design, add a rectifier, and add an inverter, and likely have to have a computer controlled throttle to vary the speed, you have just redesigned the generator from a conventional to an inverter style as all you have left is the engine. I know you will disagree with that, but that is certainly the way it appears to be from what I have seen.
Thanks Booster however I think you misunderstood me, I didn't mention adding a rectifier and and inverter to an Onan. You asked how a generator could run at slower speeds and still retain 60 cycles and I mentioned its accomplished by having a AC generator which convert to DC and runs it though an inverter.

You're right Onan needs to advance their generator technology, it would be a no brainier for them to offer a more advanced generator for RV's. As I mentioned, I have a 6500 watt Kawasaki generator that is over 10 years old and it has that technology. Onan has the business and they just keep putting out the same old technology generators. Maybe this lithium thing will get them improving their gen sets.

Mike
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Old 05-27-2019, 12:13 AM   #14
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Sadly, given the limited size of the market and the fact that interest in having a genset seems to be rapidly waining, RV genset technology is unlikely to attract the engineering investment dollars that developing a state-of-the-art unit would require. ICE is dead, and the R&D money goes elsewhere.

There is a vicious cycle: Onan gensets are ridiculously noisy, therefore almost everybody hates them, therefore they seek alternatives, therefore the momentum is with second-engine alternators and large batteries. That, combined with the hope that a practical propane fuel cell is on the horizon makes me extremely dubious of the chances that we will ever see a small RV genset that is quiet enough to be practical.
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Old 05-27-2019, 12:43 AM   #15
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Sadly, given the limited size of the market and the fact that interest in having a genset seems to be rapidly waining, RV genset technology is unlikely to attract the engineering investment dollars that developing a state-of-the-art unit would require. ICE is dead, and the R&D money goes elsewhere.

There is a vicious cycle: Onan gensets are ridiculously noisy, therefore almost everybody hates them, therefore they seek alternatives, therefore the momentum is with second-engine alternators and large batteries. That, combined with the hope that a practical propane fuel cell is on the horizon makes me extremely dubious of the chances that we will ever see a small RV genset that is quiet enough to be practical.

I would certainly agree, and the fuel cells are the prime hope at this point. Of course, we also need one that will run on gasoline and another for diesel
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Old 05-27-2019, 01:35 AM   #16
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I'm not sure which generator you're referring to, but 60 db is just about the level of conversation, so we're talking Honda type quiet operation on diesel generators. On my New Aire 8KW, once you walked around the either side of the coach, the gen was for the most part inaudible. Keep in mind, Onan is not going to put a lot of money in making gas generator quiet as the diesel, simply for the fact of the price point. They have to keep them affordable.

Both my cheapie propane generators 2500 and 3700 are around 74 DB, which is more than acceptable and no louder than the vans engine running, so neither is "Noisey" by any means. Regardless, if you need to run a microwave to make dinner or turn on the AC for a snooze, a generator will always put a smile on your face! I've been using generators in RV's for 40 years and I never had one complaint or even a one breakdown. I also never had one neighbor tell me my genny was too loud.

I guess the old saying "It Is What It Is" applies to generators.

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Old 05-27-2019, 01:51 AM   #17
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Both my cheapie propane generators 2500 and 3700 are around 74 DB, which is more than acceptable and no louder than the vans engine running, so neither is "Noisey" by any means.
You keep saying this, but anyone who has lived with an Onan knows that the claim is beyond ridiculous.
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Regardless, if you need to run a microwave to make dinner or turn on the AC for a snooze, a generator will always put a smile on your face! I've been using generators in RV's for 40 years and I never had one complaint or even a one breakdown. I also never had one neighbor tell me my genny was too loud.
What a joke. NP campgrounds (and many, many others) won't even ALLOW running genesets at night.
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I guess the old saying "It Is What It Is" applies to generators.
Well, we can agree on that, at least.
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Old 05-27-2019, 02:44 AM   #18
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The diesels in class A RVs that are Onans are orders of magnitude quieter than the air cooled ones and especially the 2800/2500 ones that are in almost all class b's. Water cooling is inherently quieter because of the water jackets, and it also requires less cooling air to the block so the case can be more enclosed and insulated.



We had first hand experience with the difference at Teddy Roosevelt Nat Park, North the last time we were there. We were on a big circle of pull off campsites so they all faced a wide open field in the middle. The sites, because they are nose to tail pull offs are further apart than back in sites by a quite a bit.


The site next to use had a huge old super C with an Onan diesel maybe 100' from us. A couple of sites further down the same side was a Roadtrek Sprinter with a 2500 Onan and probably 300'. Almost directly across the open area from the Sprinter was fiver with a 3K Champion inverter generator and was a bit further so about 350' away.


The diesel Onan, that was lots closer to us was the quietest by far and we could barely hear it when out of the van and not at all when inside with the windows shut. The Champion was much further away but louder than the diesel by a noticeable amount. It was irritating when outside and still very hearable when in the van. The Onan that was nearly as far away as the Champion was louder than the other two generators combined and extremely irritating as they ran it a lot, either charging batteries or watching movies in the evening. There was truly no comparison of the three and the diesel Onan was far and away the worst, and the gas air cooled Onan was far and away the worst. Our solar kept us full all the time we were there, which was about 5 days IIRC, running the microwave and watching movies, etc, and with the vent fan and circulating fans running all day, and we didn't irritate anyone with the noise.



We had a 2800 Onan and it was horribly loud, shaking, and smelly.


So, in the short term picture, with big battery banks getting more common and air conditioning desires also wanted, along with the big inverters now used, would it be more desirable to just have a 2500 watt DC generator, which would just be a motor and alternator with regulator. That would get rid of the issue of slow battery charging off the generator that is currently limited by the shore charger size but still allow AC use continuously. The overload shutdowns at compressor restarts would just be absorbed by the batteries similar to the hybrids now but with nothing special needed like a hybrid. This would also allow it to be set at whatever speed, output you wanted/needed either manually or automatically like Idleup would like it to. If only AC running, it could be at 1000 watt output probably. Basically replace the engine generator with the same thing, different power source so no autostart conflicts, possible idling rules, running vehicle engine all the time, etc. Certainly not the long term solution to it all, but might be a decent compromise in between.
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Old 05-27-2019, 02:57 AM   #19
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You guys are great - Your reply's are interesting and for the most part, I think we're all saying the same exact thing!

Forget generators, whoever invests in piston generators is going lose money - It's all going to end up with lithium gentleman - Tesla's (Elon's) cells from his mega plant are setting all new standards in lowing the price to where lithium will be commonplace in most every vehicle and RV.

All we have to do is wait a few more years so they are affordable!

Regards - Mike
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Old 05-27-2019, 03:46 AM   #20
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You guys are great - Your reply's are interesting and for the most part, I think we're all saying the same exact thing!

Forget generators, whoever invests in piston generators is going lose money - It's all going to end up with lithium gentleman - Tesla's (Elon's) cells from his mega plant are setting all new standards in lowing the price to where lithium will be commonplace in most every vehicle and RV.

All we have to do is wait a few more years so they are affordable!

Regards - Mike

Yeah, but you still need a method to replace all the power to the batteries, hopefully without having to drive or idle the van all day. Some here drive plenty to not have an issue, but others like to stay put in one place for longer periods so that can get complicated if you are using big power for air conditioning. Ideally, the fuel cells will get big enough, cheap enough, and small enough to be able to keep up with all that energy replacement when necessary, but until they, or something else, is ready we are realistically looking at either engine generators or standalone generators, as there really is no other non grid option available.
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