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Old 02-13-2014, 07:04 PM   #1
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Generator - on engine or separate?

The Roadtrek 190 can be ordered with either the generator attached to the engine or as a separate unit. They are both gas. The wattage differs a bit between the two units.

What I don't understand is how you would choose which way to go. What are the plusses and minuses? I image one downside is having to idle the van's engine for long periods - or is it? Maybe you save some space that the stand-alone generator takes up? Or maybe you are creating a service nightmare by having a generator packed in the engine bay? Or maybe you are reducing maintenance by only having to service the engine.

The cost either way is close. So how do I decide?
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Old 02-13-2014, 07:15 PM   #2
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The Roadtrek 190 can be ordered with either the generator attached to the engine or as a separate unit. They are both gas. The wattage differs a bit between the two units. What I don't understand is how you would choose which way to go. What are the plusses and minuses? I image one downside is having to idle the van's engine for long periods - or is it? Maybe you save some space that the stand-alone generator takes up? Or maybe you are creating a service nightmare by having a generator packed in the engine bay? Or maybe you are reducing maintenance by only having to service the engine. The cost either way is close. So how do I decide?
Looked at the road trek website.

Generator – engine mounted 3500 W with 2500 W 12/110V power inverter - U.S. $3,822

Generator - conventional - 'Onan MicroLite' gasoline, remote-start, 2.8 kW - U.S. $3,497

I would go for the conventional Onan. Don't like the idea of idling the main engine for hours at a time. Definitely get the 200 watt solar package as well, this will cut down the amount of time you need to run the generator.

A third option would be a self contained portable generator, like a honda EU2000i or similar, but it might not run the A/C and you would have to take it in/out as well as refuel it. The built-in Onan is just push a switch simple.
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Old 02-13-2014, 07:26 PM   #3
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I like the 40th anniversary package - you get all the solar kit integrated in the new cap design, plus the chargers/inverters, etc. and extra batteries. But that wasn't the question.

The generator choice is another option instead of integrated into the "package" for some reason. But I hear you on the engine idling. I would think that you couldn't do that with a gas engine - thought it could lead to engine overheating or fires from exhaust over-heating.
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Old 02-13-2014, 09:24 PM   #4
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I have the engine mounted 3.5kw generator on the diesel Sprinter. I've rarely had to use it while camped, but when I have it charges quickly and the engine idling is relatively quiet. That is important to me. If you plan to run the generator for hours while camped, then the Onan is probably a better choice. Go for the solar panel and extra batteries for sure.
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Old 02-13-2014, 09:34 PM   #5
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My best friend has a Roadtrek and the 2.8 Onan is obnoxious. He hates the noise it makes.

The diesel generators generally have a deep somewhat pleasing tone, the bigger Onan's a bit higher tone but not so bad but the 2.8 is much higher and not something you want to listen to at all. My gas Onan 7000 is a MUCH quieter and pleasant tone than his yet I still use a Honda 2000is unless I run the a/c or heat pump or am running down the road with the roof a/c's on. Much less gas, quieter and no vibration because I set it on a board on the ground so it doesn't touch the RV.

He bought a Honda 2000is just because of the sound.
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Old 02-14-2014, 07:55 AM   #6
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One element in the different generator sound levels you mention is the frequency. The smaller single cylinder Onans run at 3600 RPM. The larger two cylinder versions run at 1800 RPM. Hondas, up to and including the 3000 W, are inverters. This, and the general quietness of the Honda design, results in the much lower sound levels.

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My best friend has a Roadtrek and the 2.8 Onan is obnoxious. He hates the noise it makes.

The diesel generators generally have a deep somewhat pleasing tone, the bigger Onan's a bit higher tone but not so bad but the 2.8 is much higher and not something you want to listen to at all. My gas Onan 7000 is a MUCH quieter and pleasant tone than his yet I still use a Honda 2000is unless I run the a/c or heat pump or am running down the road with the roof a/c's on. Much less gas, quieter and no vibration because I set it on a board on the ground so it doesn't touch the RV.

He bought a Honda 2000is just because of the sound.
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Old 02-14-2014, 08:21 AM   #7
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I think the vehicle driven generator is a great idea. Even my V10 Ford doesn't burn any more gas at idle than the gasoline generator in our unit. And, the vehicle engine is way quieter. When dry camping I always recharge the house batteries by running the engine just because it's quieter.

Also, on really hot days while driving you'll be able to run your coach air conditioner. No extra cost like you would have with separate generator.

I wouldn't worry about idling. It's not that hard on the engine and you seldom need to run for long periods of time anyway.

For the weight savings, space savings, noise and convenience, my choice would be the vehicle driven generator.
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Old 02-14-2014, 12:46 PM   #8
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I talked with a dealer today that also is a Chevy dealership. He said not to worry about idling and agreed it would be much quieter. Also, said it puts out 280 amps!

Well, I would expect some load on the engine when the "generator" is engaged - is it more or less efficient than a stand alone genset? Surely there is a cost to it in fuel. Also, not sure if there is a failsafe to prevent fuel run-out if you were running for a long time - suppose not.

It's a total setup by the manufacturer, so hopefully the generator, inverter, controller and solar are all well matched.
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Old 02-14-2014, 01:02 PM   #9
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The Onan is remote start. Can it be fitted with a auto gen start module? This would make it the preferred choice over the one hooked to the main engine. If the batteries get below a certain state of charge, the Onan generator starts up automatically, runs for a programmed time, and then shuts off. The one hooked to the main engine probably can't do that, and I would be scared of it if it was ! I wouldn't want the main engine starting by itself in the middle of the night, but it would be okay if the small generator does.
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Old 02-14-2014, 08:49 PM   #10
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Well, I would expect some load on the engine when the "generator" is engaged - is it more or less efficient than a stand alone genset? Surely there is a cost to it in fuel.
Yes, the engine-mounted generator does not provide free power and it will consume just as much additional fuel in relation to load as a separate generator, that's just physics. There may be some fuel-consumption advantage in not running a separate engine but I wouldn't expect the difference to be large.

I would also be concerned about idling for long periods as this just isn't good for any engine, although the engine may automatically go into a fast idle mode when the generator is engaged and if so that would help mitigate such issues. And the Sprinter diesel engines in particular are known for not liking long periods at idle as it can load up the very expensive-to-replace EGR and DPF emissions components.

I think the main plus point in the RoadTrek application is that by deleting the separate generator you save weight and space that can be filled with batteries, taking better advantage of the solar system, and that may indeed make sense in that particular application. But for the same price, in a more conventional installation I think I'd prefer the separate generator if I planned on long runtimes. The usual high-capacity alternator found on a modern RV can generate more than enough power when underway to recharge the house batteries.
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Old 02-14-2014, 10:58 PM   #11
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Pas - I don't think I'd ever opt for any kind of auto start feature. With 4 batteries, I doubt there would be any need for that - running a furnace all night is not going to drain them. The refer and cooktop are both propane, so all that would need gen power is really AC.

Smiller - well stated. Think I'll be calling the factory to see if I can dig deeper with them on understanding the setup/components available. The dealer's knowledge is a bit sketchy.

The 190 looks to be quite different than the e-trek (sprinter). On that coach, the cooktop is induction and the refer is electric. So it's loads on the battery/inverter are much higher. The 190 is only using your typical 12v loads - lighting, water pump, furnace blower. Microwave and TV on inverter. AC/heatpump on 120v (generator). Four 6v batteries plus the solar panel should give quite a bit of time out dry camping if you don't need the AC, or the microwave.
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Old 02-15-2014, 12:00 PM   #12
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I talked with a dealer today that also is a Chevy dealership. He said not to worry about idling and agreed it would be much quieter. Also, said it puts out 280 amps!

Well, I would expect some load on the engine when the "generator" is engaged - is it more or less efficient than a stand alone genset? Surely there is a cost to it in fuel. Also, not sure if there is a failsafe to prevent fuel run-out if you were running for a long time - suppose not.

It's a total setup by the manufacturer, so hopefully the generator, inverter, controller and solar are all well matched.
Thats 280 amps at 12volts.
Thats 28 at 120V .

Id like to see the spec because most aren't that stout.

The news truck guys tried these systems and went back to standard onan 7K's.

UD
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Old 02-15-2014, 12:50 PM   #13
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Pas - I don't think I'd ever opt for any kind of auto start feature. With 4 batteries, I doubt there would be any need for that - running a furnace all night is not going to drain them.
What some don't realize is that if you run the batteries too far down even by accident because you aren't monitoring them constantly, they will be damaged. The damage adds up, and you might need to replace them at a cost of $400-$500 long before they would normally. Well maintained batteries can last 8-10 years. Neglected batteries can need replacement in under 2 years. The auto start feature frees you from having to constantly monitor them.... generator does that task for you.
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Old 02-15-2014, 02:39 PM   #14
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Taking them down to 50% (which is what is generally recommended, even for AGMs is about 250 amp-hours. The little furnace blower in a van is 1-2 amps. Remaining loads in the coach are 3-4 amps. You just are not going to get that much consumption overnight that you need things turning themselves on. Granted, you have to monitor your battery panel each morning and evening.

Your thinking is for appropriate for a big coach with heavy loads - residential refer, big furnace, significantly more lighting, etc. They can zip thru their battery capacity fairly quickly thus making it a wise choice to have a generate come on automatically.
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