Wednesday, January 9, 2013

The Roadtrek Generator

This is the third article in our series of Electricity in the Roadtrek and the second electrical system we are going to talk about. An electric generator is an option when ordering a Roadtrek. If you have a gasoline engine Roadtrek - the Chevy based Roadtreks - you will get a generator that runs on gasoline. If you have a diesel fuel engine Roadtrek - the Sprinter based Roadtreks (with the exception of the new ETrek) - you get a generator that runs on propane.

The generators that Roadtrek uses are made by Cummins/Onan and the gas generator model that is installed will generate 2800 watts* of 110/120 volt AC power. This is enough power to run just about everything electric in your Roadtrek at the same time - with the possible exception of running the air conditioner AND the microwave at the same time*. The generator in my Roadtrek 190 Popular is located under the chassis on the passenger side rear of the van. It is secured to the bottom of the chassis and has an exhaust pipe that runs to the rear driver's side corner of the fan just below the bumper and exhausts to the side. The gasoline generator gets its fuel from the van's gas tank and is connected to it's own gas line. The line* is positioned in the gas tank so that it prevent the generator from operating if your gas tank goes to 1/4 tank of less so that you cannot get stuck and not be able to drive away if you continue to run your generator to the point that there is no gas - you are prevented from doing this.

The generator is connected to the 110/120 volt* electric circuits in the Roadtrek and while the generator is running you can operate the 12 volt lights, all of the 110/120 volt outlets, all appliances, and also charge the coach and the engine batteries. While the 12 volt electrics will be drawing from the batterie(s), the batteries are being recharged at the same time. Be aware that not only is running the generator noisy, but the exhaust is deadly and the exhaust pipe must not be obstructed outside. It is extremely important that you know your Carbon Monoxide detector - located on the ceiling of your Roadtrek over the bed area - is working properly. This will save your life should exhaust somehow come inside the Roadtrek. Do not open the rear windows over the generator exhaust when running your generator.

Many campgrounds have rules about when you can run your generator because of the noise. If you are camping in a parking lot or field where there are other RVs be aware that your generator may disturb those around you. There are certain camping courtesies about this to be aware of.

Anyway - let's get you started using your generator. It is simple IF you follow these steps -

1) Turn on your Battery Switch. You need the battery power to start the generator.

2. Start your van engine. This will give the power to start your generator a little extra boost that will prove to work every time when you are having a hard time starting your generator. Just start your engine and let it run while you go to the next step.

3. Push the generator switch on the wall of your Roadtrek. Push the switch at the top.
Switch on the left - Meter on the right is how many hours your generator has run since installation.
 Hold the switch in until the generator motor kicks over and starts and keeps running. If you let go of the switch and the generator stops, push and hold the switch again. You may hear the sound of the motor pulse or rumble. It will catch and run steady.

4. Let the generator run for a couple of minutes before turning any appliance on. You will hear the sound change to a more steady run - and then you are ready to use your generator's power. If you try to start a large appliance like your air conditioner before the generator is ready, the air conditioner will not have enough power for the compressor to start properly. Just avoid this and give the generator a chance to come up to full power.

5. Once the generator is going - TURN OFF THE VAN ENGINE. Why waste gas?

Your generator is now running and you have full use of 110/120 volt generated power in your van. Simple. You use about 1/3 a gallon of gas in an hour. I am not sure how much propane the propane models use but I have heard that the propane generators are not as efficient as the gasoline generators are - and this seems to hold for generators in general (not specific to the Onan).

When you are ready to shut off the generator, first turn off all appliances using generator power - A/C, microwave, TV, etc. and then JUST PUSH THE BOTTOM OF THE GENERATOR SWITCH. The generator will come to a rumbling stop. If you don't need battery power for any reason, turn off the battery switch.

Simple, but the story does not end here, unfortunately. Having a generator means devoting time to it on a regular basis to keep it properly maintained and working so that it is always ready and working when you want it to be.

The generator must be "exercised" under load for two hours* every month. What this means is that you need to go out to your Roadtrek and start your generator and then put a load on it - half load is recommended which is either the air conditioner or the heat pump or a plug in electric heater - and leave it running for two hours. And you must do this every month. If you look in the Roadtrek manual it will talk about doing this for a half hour every month - BUT - the Onan manual says two hours and my dealer service told me that if there is a problem that requires warranty repair they have to tell Onan how many hours are on the meter - and if those hours don't at least show the exercise time for the age of the generator, they do not have to cover repairs under the warranty. But there is good reason to do this other than to make Onan happy. The generator really does need to be run this way. Some owners use the generator more exercising it this way than they do actually using it- me included.

The oil must be changed on the generator after the first 20 hours of use. After that the oil is changed after every 150 hours or at least once each year. See the manual for the type of oil to use. This varies by the outside temperature the generator is operated in. The most usual temperature range 10dF to 100dF should use 15W-40. Many change the oil themselves - it takes just one quart of oil. I have our dealer/service center change the oil. It is necessary to crawl under the Roadtrek to access the generator to do anything to it. This includes checking the oil and changing the oil and filter which should also be changed every 150 hours, There is a maintenance schedule in the manual. Here is a link if you don't have a manual.

You are supposed to check the oil every eight hours of use. This means crawl under, open the hatch on the generator and unscrew the oil cap and check the level. The van must be on level ground  (lots of luck). Unscrew the oil cap and pull out - the dipstick is attached. Wipe it off and then reinsert WITHOUT SCREWING IT IN. Pull out and read the level. If you need to add oil you must try to pour it in to that hole with a funnel or some other device. I found a pump that fits on the oil bottle and pumps the oil up into the hole through a hose. (I have not yet had to use it.)  IF THE OIL GOES BELOW HALF the generator will not operate. If you have a problem getting your generator to run or it just suddenly stops - CHECK THE OIL LEVEL.  You can find 15w-40 oil in Walmart or an auto store.

There is an adjustment to be made on the generator for high/low pressure changes - like going up into high mountains. See the manual about this. So far we have not been anywhere that would need this adjustment. 

Something else that is very important to know about your gasoline generator is that it cannot use Flex Fuel* so even though our Roadtrek can use Flex Fuel, we cannot put it in the tank because it would ruin the generator. The generator is fine with E10 ethanol. Some find it beneficial once a year to put a gasoline additive that will remove the clogging effects of ethanol on small engines into the van gas tank and run that treated gasoline through the generator. There are various gasoline additives that are available that will clean your engine and generator motor of ethanol deposits. There has been a discussion lately as to what is best and one product that several have used is under debate as to whether it does this properly or not. What you want to get is a gasoline additive specifically for ethanol treatment.  IF YOUR ROADTREK HAS A PROPANE GENERATOR YOU DO NOT DO THIS.

When you need the generator, all of this is well worth the effort - even though it often feels like a pain for the few time the generator is used. But when we needed the Roadtrek powered in a Blackout - the generator came to our aid! If considering buying a Roadtrek  - or any RV - you really do want a generator. The new ETrek Roadtrek has a completely different generator that runs off the van engine and will charge the batteries in a half hour. There are innovations coming!

 Here is a link to an excellent set of photos of the internals of the Onan Generator that is in our Roadtreks - Generator Photos 
Thanks to the site - Red Rover the Roadtrek.


Jim Hammill, President of Roadtrek, after reading this article suggested I add the following. Also, please note that my articles are not "Roadtrek Factory Authorized". They are based solely on my experience, observation, and learning from other Roadtrek and RV owners. 

1.Propane generator in Sprinter is a 2500 KW not 2800 KW. Gas Generator is 2800 KW. 
2.In many situations, the generator will run the microwave and the AC, and in many situations it will not. It depends on how hot it is outside, causing the AC compr
essor to draw more power, and how many other items are on in the van. 

3.The generator is not connected to the vans gas line. There is a special gas pickup tube installed on the GM gas tank, so the generator has its own fuel line.

4.We at Roadtrek guide consumers to run the generator under a small load for 45 minutes a month when using infrequently. 2 hours would be used when you don't do it every month. 2 hours is extreme and in our opinion, far more than needed for routine maintenance.**

5.Another option is to just run the generator out of fuel before you store it, by installing a fuel shutoff switch on the generator fuel line. of course, remember to turn it back on in the spring. 

6.There is no cut off switch that stops the generator from working when the tank reaches 1/4 full. The gas tank pick up tube is mounted higher than the vehicle pickup tube to ensure the generator runs out of gas first.

7.The generator is not connected to ALL the electric circuits in the unit, as it goes to the inverter/converter/charger, which simply charges the batteries, and creates 12 volt power. The batteries power the 12 volt circuit.

8. As a comment, just run mid grade gas or higher in your Roadtrek to avoid the E85 issue. Modern cars and trucks have fuel injectors that handle it. Carburetors on generators have small ports that gum up. This is not a big deal at all, and consumers should just use 87 octane or better.

**Because of how strongly my Roadtrek service center emphasized Onan's insistence that the generator be "exercised" for two hours each month or Onan can refuse to honor the warranty for any repairs, I will continue to run the generator each month under load for the two hours. This is something where Cummins-Onan and Roadtrek differ in opinion on and while I am sure Roadtrek has reason to feel that 45 minutes a month is sufficient, Onan is the company that the service center will have to go to for approval of any warranty work. Since I use my generator rarely when traveling, exercising it is the most use it gets.


  1. Nice article. How long can the generator be run on a hot day or night to operate the a/c?

    1. The generator uses a little more than 1/3 of a gallon of gasoline per hour. The generator will draw gas from the van's gas tank until the tank reaches 1/4 full so that it does not use all of the gas in the tank and leave you stranded. So if you have a full tank (about 32 gallons) you could run the generator to operate the A/C continually for about three full days. It is likely no one would do this but it is possible. The generator makes a lot of noise - we have yet to try to sleep with it yet. I know that many do this - but in the bed in the back of the van you are right over the rumble of the generator. But if you had to - you can go just about three days using the A/C, the lights, the TV, etc.

  2. Thank you Meryl for this explanation that should have been provided by Roadtrek, especially since touting their business since 1974. Nowhere does the owner's manual even say where to fuel the generator on the vehicle. Nor does the Onan manual, unless you read all the minutia and figure it out on your own. All these maintenance requirements you discuss, and we owners cringe over, could be avoided by Roadtrek just supplying a propane-fueled generator. I have one at my home and it only requires occasional oil changes (sometimes as seldom as 3 years apart or more), NO OTHER LIQUIDS. I would gladly give up 300 watts of power for this convenience. Instead, I'm wed to Roadtrek generator (and other components) maintenance. Bob Ross.

    1. The Roadtrek Sprinters because they have diesel engines have propane fueled generators. This past year Roadtrek introduced a new type of generator that runs directly from the van engine and is located under the hood. It works with the gas engine or the diesel engine as it seems to have no motor of its own. This does mean that when in need of the generator the van engine must be running. It is claimed that this does not use any more gas per hour than the Onan. It is now an option on Roadtreks and can be retro-fit at the factory on older Roadtreks by special arrangement with the factory. This enables the use of the space the Onan takes up under the van to be turned into space for additional coach batteries. I know of a few Roadtrek owners who have had the upgrade to this new generator done and they seem happy with it. This eliminates most of the maintenance that the Onan requires.

  3. Do you know the electrical output from the engine alternator? I'd like to be able to figure the time to charge the house batteries with the engine running. BTW I have a 2002 190 Popular on a Dodge 3500

    1. I can only tell you that per the notes on the Roadtrek Electric Simulator - see the first article on the Electric system for the link, running the engine at idle for about two hours will give a significant charge to all of the batteries. I am not sure if you will get them to full without running the engine longer at idle. I know that driving for about two hours - at least in my 2011 Chevy 190 - will charge the batteries almost to full.

    2. I should add that the electric system in a 2002 Roadtrek is very different from Roadtreks after the Tripp-Lite single unit combination inverter/converter/charger started being used. The 2002 has an inverter and a another unit that is a converter/charger.

  4. will the engine generator run the roof air while parked, and boondocking

    1. This is something that you will have to contact Roadtrek to ask about. The engine generator is new and I do not have one. I have opinions about it but cannot say what it is capable of. It works very differently from a regular generator like the Onan which is still available.

    2. I have run the roof air using the generator in my 170 popular. I have run both the A/C and Microwave at the same time. The A/C seems to run even when plugged into my house power, although I am not sure if that is recommended or not haha.

    3. I have run the Roadtrek A/C when plugged into my house outdoor outlet. It all depends on how much amperage is on the circuit breaker on that outlet. My outlet is 20 amps and it is the only thing on that circuit breaker in the house - so all of that 20 amps can go to the Roadtrek. If you are going to run the A/C when plugged into the house - check how many amps are on that circuit breaker in the house and if there is anything else on that circuit breaker that you are sharing those amps with. A 15 amp breaker is cutting it close even if it is the only thing on - but it will work - just don't put anything else on inside the Roadtrek that will draw a lot of power. Always use a 30 amp extension cord - one as thick as and matches the power cord on the Roadtrek to avoid overheating and a fire. As to running the A/C and microwave on the Onan generator - the generator has 2800 watts to give - that should be enough to run both the A/C and microwave BUT it is close. IF it is too much the Onan would shut down - and you may have to go inside the Onan case to reset its own circuit breaker - which means crawling under the back of the van to get into it.

  5. Yet another very useful article for us Roadtrek owners. I am about to start pulling a 30 amp travel trailer with my 170 popular. Do you know if there is a way to connect the Roadtrek's built in generator to power the trailer in a boon dock situation?

    Thanks in advance,

    1. The only way that I am aware that you can connect the generator to power anything outside the Roadtrek would be to run an extension cord from the trailer to inside the Roadtrek and plug into the Roadtrek though an open window and lug it onto one of the 110 volt outlets inside the Roadtrek. This limits you to only the number of amps of the circuit breaker in the Roadtrek panel for that outlet - 15 amps. The 170, like my 190 has no 110 volt outlets on the outside of the van, so you have to go inside. If you are inside the Roadtrek and someone is in the trailer at the same time the trailer is connected to the power, all of the outlets inside the Roadtrek that are on that same circuit breaker are also sharing that 15 amps. There is a breaker for all of the outlets on the driver's side and a circuit breaker for all of the outlets on the passenger side. Chances are you are going to overload the breaker and it will trip. You would be much better off getting a small Honda generator for the trailer - carry it inside the trailer while you are traveling and setting it up just for the trailer when you stop. Set the portable up a distance from both the trailer and the Roadtrek so that you don't get the CO exhaust brought into either one - good idea to keep the Roadtrek and the trailer a distance apart also if you are going to connect the two through an open window.

  6. we would need to run an oxygen concentrator that pulls about 500 watts 24/7. Looking at Mr. Hammill's comment #7 above, would that be feasible if at some point we were using the generator only for power?

    1. If your oxygen concentrator is a 110 volt appliance - it must be if it draws 500 watts, you would be plugging it into the 110/120 volt electrical system in the Roadtrek so with the 2800 watt Onan generator you should have no problem plugging it in and running it with the Onan generator. In the past two years there is a new generator option in the Roadtrek which is an engine generator which runs the engine to generate electricity to charge the batteries in the Roadtrek and that is charging the batteries and then the battery 12 volt power is run through a larger inverter than is in the Roadtrek with the Onan and that is powering 110 volt appliances when using that generator rather than how the Onan works. So if buying a Roadtrek now with the engine generator rather than the Onan (the Onan is still available) you would need to ask your question to Roadtrek's customer service. If you want the Onan, I would still suggest that you talk to Roadtrek and Onan just to be certain, but I have heard of many who use an oxygen concentrator in their Roadtreks through the generator. One word of caution though is that the generator is dependent upon how much gasoline you have in your vehicle gas tank (or propane if you have a diesel Sprinter Roadtrek). If your gas tank drops below 1/4 the generator automatically shuts down so that you are not stranded without gasoline. The Onan generator works no differently than any standalone generator such as one might buy for their home to have power during a blackout - its limit is by how many watts you are going to plug into it. Again, the gas Onan is 2800 watts.