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Old 08-31-2015, 10:46 PM   #1
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Let's talk about diesel generators

I have a Power Tech PTRV-3 RR (RR = remote coolant reservoir) in my 2012 RB build.

While planning for the build my sales guy consistently expressed that he and SMB West really didn't think that on board generators were really efficient, worthwhile, or offered good value. Still we persisted based upon what we felt we needed.

The generator complicated the build and reduced our propane tank to a small 5 gallon size (works just fine for us though). Due to the short wheelbase and the size of generator we lost the decent sized propane tank we needed for a generator and heater and stove so were forced to use the van's diesel fuel itself.

The biggest issue for us is that it reduced our ground clearance to just a little over 7". On a longer wheelbase it should fit between the frame rails and not hang down as low as ours, at least that's what I read somewhere. As a matter of fact I think it might have been able to be installed the same way with our build but maybe something got in the way due to the complexity of our build.

So we gave up some convenience on our build and we paid a whole bunch of money and what did we get?

We got a way to recharge our batteries when we needed without moving the van. We also get to run our air conditioner when parked. I'll tell you, we were sitting in the van while car shopping in Sacramento one day and it was right around 100 degrees. We had the dogs with us so one of us sat in the van while the other beat up on the sales guys and it was really nice to just hang out perfectly comfortable on a cooker of a day.

We persisted and got our generator and we even get to use it as planned but there's more.

Unfortunately our generator has become a real problem this last year. It started out where it would run for ten minutes and then just stop. We thought that we got that fixed, we were told that the engine was sensitive to low voltage so if necessary just start the van engine and run until the generator would run on it's own. Seemed to work... for a while.

Recently the generator won't even start so it's sitting in the shop now.

We love having a generator but it is getting to be a hassle and expensive to maintain.

I would like to know if some of the rest of you are having the same issues that I am having or maybe something different. Maybe we can help each other here.

I'd also like to know more about why you decided to go with a generator and especially why a diesel.

I hope that you are experiencing trouble free generator use but my mechanic has been telling me that these generators are known to be a bit problematic so...

Thanks.


Chumley
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Old 08-31-2015, 11:25 PM   #2
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Re: Let's talk about diesel generators

Chumley,

My exposure to diesel generators is in larger boats/yachts. One thing that was drummed into me was diesel engines need to be run with a good size load otherwise they become problematic due to incomplete combustion which leaves residues which create clogging. When we ran a diesel generator it was scheduled to run water maker, big battery chargers, laundry and /or turning on the a/c or heat even if it wasn't necessarily needed. We wanted to hear the engine sounding "loaded".

I think one mistake people with diesels is to over spec capacity for the common usages which then runs them too lightly loaded. The same may hold true of the diesel furnaces based on some discussions I have read.

So if you have a 3 kW diesel generator and it is being run only to charge a 400 Ah battery bank, it is being too lightly loaded. Running the A/C would probably represent a better load.

I think for the size of most SMB rigs and the demands of most users, especially of it is non electric stove based, a gas or propane fueled generator makes more sense. Smaller, quieter, cleaner and less troublesome. The small Honda and Yamaha sets can be set up to run on propane.

Just my 2 cents. I am sure others will have some very good feedback.
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Old 09-01-2015, 05:23 AM   #3
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Re: Let's talk about diesel generators

Dont know why you say it reduced your ground clearance, maybe yours is not installed right, if installed right , its a little higher than the rear differential.
I have the Powertec PTRV-3 and NEVER a problem. I can run everything at the same time (110 AC, fridge , and microwave). I run it once a month for an hour or so when not being used (with no load) (I also run my Espars) Ive used it during power outages at home . I put the food from the house refrigerator into the sprinters refrigerator and using the exterior outlet, I powered 2 chest freezers, a couple of lights , TV/cablebox/ and computer for over a week ... NONSTOP ( gets 3 1/2 days before the fuel level of Sprinter would get to 1/4

when parked at dog trials, I run the gen all day, so at night I have a full house bank
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Old 09-01-2015, 07:17 AM   #4
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Re: Let's talk about diesel generators

Chumley, if you haven't already you might want to also post this over at the Open Roads Forum where there are a lot of diesel RV guys, mostly big full time pusher owners but still, this might give you a lot more exposure to diesel generator owners and troubleshooting them.

Good luck!

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Old 09-01-2015, 04:31 PM   #5
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Re: Let's talk about diesel generators

1der, we always run the generator with a load even if running it is intended just for battery charging. You can always run the ac on heater or cooling mode. This was definitely drummed into me early on when talking with the manufacturer right after delivery.

We do (did...) run the generator on load religiously for an hour a month. Funny story is that the local Power Tech repair shop is run by a very old and cranky guy that told me that running it for an hour every month is as bad as just taking a hammer to it and beating it. Love those old timers… wait, I am one…

I think I mentioned in my write up that longer wheelbase Sprinters can usually get the generator installed higher in the chassis between frame rails. Mine is mounted across the rails and therefore used to hang down to about 6” above the ground. Adding the spring assist kit took it back up a little over 7”. It rarely hits the protection stand offs with the little steel wheels now. When they do hit it sure gets your attention!

The shop could not get it to fail yesterday and ran it for an hour or so. We are concerned that it might be an intermittent problem which, of course, means flat out annoying and inconvenient. I described the problem to them and they will keep it for another day or so and try to get it to fail.

The story behind this generator repair visit goes like this.

We learned from our earlier repair visit that if the unit doesn’t start then you have to go and remove the panel on the side (back of k9sprinter’s most likely) and reset the ECU on/off reset switch. This will clear the error codes that will be flashing on the interior start/stop switch and reset the unit to start again.

We were told that the generator did not like lower voltages and that its starter should be connected to chassis power. This would avoid the potential condition where the batteries are low and the generator is to be used to recharge the batteries. SMB West connected our starter to the coach batteries so if the batteries are low then the generator may not start, or so we are told and it seems to be true. They said they always install them this way and think it has to do with Mercedes’ concern about warranty and keeping the chassis separate from the coach system.

We learned to turn on the engine if the generator wouldn’t start so it worked that way for a while.

We used it during the visit to the car dealership in Sacramento that I mentioned and it worked fine for maybe 4-5 hours. The next day we returned from our trip where we had continued on to overnight in Carson, Nevada, and came down Highway 50 and then many freeway miles. The batteries were topped out as far as the alternator would charge them and we stopped on the way home for a bit. I went to start the generator so we could turn on the ac and it just cranked and cranked and nothing. It did this 3 times, as this system is programmed to do, and then it stopped and nothing. I reset the switch and started the engine and then tried it again after a while. Still no starting.

Disappointment!

So now with all of that information the repair shop will try to see if it fails. My guess is that he won’t be able to recreate the problem and it goes away until the second day camped by a lake in Canada or Alaska and we can’t get the generator started. Such is the nature of intermittent problems.

I know that not everyone has a problem generator and it is good to see that represented here. I also see that not everyone sticks to the “factory recommended regimen” and their generator works just fine. Sometimes you just do what works and for me that is nothing right now.

So what else are you all doing and how is you generator treating you?

Thanks.


Chumley
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Old 09-02-2015, 11:59 AM   #6
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Re: Let's talk about diesel generators

Chumley, we have the same generator on our 170" Sprinter. The clearance is about 9 inches and we have hit our skid wheels numerous times without problems. SMB at first told us that this generator would not fit under the rear of our van. After advice from k9sprinter and consulting with the manufacturer and the Texas SMB staff, the Huntington guys were able to modify the mounting brackets on the generator so it would fit between the frame rails.

We chose this diesel generator because it will run a full week on a full tank, and the Onan propane generator would run only 24 hours which means not being able to run the A/C overnight. After 2.5 years we have in fact never run the generator overnight (last summer we were in Alaska).

The only problem we have had with the generator was when we ran out of fuel when the tank got below 3/8 full (thinking we could use it until 1/4 full). After filling the tank, the generator would start but the rpms would cycle up and down every 10 or 20 seconds. We soon learned that air in the fuel line caused this and we had to bleed the injector. This is not difficult after learning how. Use a 17 mm wrench to loosen the nut on the stainless fuel line leading to the injector, near the bottom of the opening on the rear of the generator. Loosen it just slightly, have someone start the generator, then close it after cranking for about 5 seconds. You may have to do this more than once.

I am not sure but I think a poor calibration on the fuel gauge caused it to read high after a lot of use by our diesel furnace. I mean to do some tests on that but have not gotten around to it.

Later we again could not start the generator. Thinking it was lack of fuel, I tried bleeding several times with no luck. Then I saw that there was no fuel from the fuel pump. PowerTech sent me a free one which I installed in about two hours (not an easy job). SMB did not have a filter before the pump and I think some crap in the line jammed the pump.

So it runs great now and we are careful to have the fuel gauge well above 3/8 when we are heading for a camping spot where we may need it or the furnace.

I have changed the oil in the generator once. I needed a hand-operated pump to pump oil into the hard-to-reach filling spot. There is no filter on the oil system, only a screen and magnet which I cleaned.

David
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Old 09-02-2015, 01:55 PM   #7
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Re: Let's talk about diesel generators

For our build we had to make a serious design decision between the PowerTech Diesel generator and an all-electric alternator based system.

I don't want or intend to divert this thread into a debate against the Diesel generator because I still feel it's a great option even though we ultimately decided on an electric implementation.

Diesel Generator Pro's and Cons:
Pro - Maximum run time of the genset is measured in days, not hours
Pro - Capacity is not an issue - 3KW can run everything in the coach including AC/Heat and Microwave.
Con - the bottom of the installed generator creates a departure angle problem on steep driveways, etc.
Pro - The weight of the unit is 260lb, roughly half of an 8 battery bank
Con - When running the generator it is loud. Unacceptable for many situations like city streets, close camping in campgrounds, etc.
Con - Maintenance. Oil changes, fuel and air filter changes, and a calendar reminder monthly to run the genset.

Electric-Alternator Pro's and Cons:
Con - Maximum run time is 5-6 hours with the Air Conditioning running continuously (this is measured not theoretical)
Con - While capacity is theoretically 4KW via the Inverter, super big continuous loads will pull the run time down precipitously
Pro - With a properly designed install the battery bank doesn't change the stock departure angle of the Sprinter van.
Con - The weight of the battery bank is roughly 530lb, heavier than the diesel generator.
Pro - The system is silent, excepting when idling the van for a recharge. Even when idling the van it is much quieter and more socially acceptable than the generator noise level.

In our case we installed the "second alternator" option on the engine. Sportsmobile installed a 270A alternator, which is wired exclusively to the coach battery bank and provides approximately 3kw of charge.

Due to the known issue of idling the Sprinter 6 cylinder, we ordered the factory high idle option to bump up the idle while charging.

To address the 5-6 hour maximum air conditioning time issue we installed a vehicle autostart system that senses when the voltage drops (to 11.5v I think) and then starts and idles the van for 60 minutes to put a partial charge back on the battery bank.

So I can't report on the actual real-life usability of this system as we are picking it up on Friday, but our hope is that we can pull into any parking place and keep the van cool via rooftop AC without making any objectionable noise. Also we can dry camp in a hot environment without annoying our neighbors or friends.
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Old 09-03-2015, 04:12 PM   #8
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Re: Let's talk about diesel generators

David, I'm going to have to keep better notes on the conditions when the generator won't start. I wonder about the fuel level in mine effecting the generator now. I'll be watching the battery level and fuel level closely next time I try to start it.

I run the problems through my head and I have a hard time with it since I'm doing everyhting the same was as before only now it won't start.

So my worst fears have been confirmed by the shop - they can't replicate the issue. At least if there is a problem then we can start the process of fixing it, no matter how much it costs or how long it takes.

I went in and picked up the van and pushed the start button and sure enough it starts right up.

The generator purrs like a kitten now.

One thing I never mentioned was that SMB West installed the generator with both the vibration isolated mounts and the backup mounts bolted securely to the rig. This created a situation where the whole van vibrated in an annoying manner when the generator was running. My local shop told me about this and when asked about a better solution they recommended that we put in some aircraft cables in lieu of the rigid straps. The shop put in the cables and now there is virtually no vibration. Still makes a lot of noise but no real vibration.

So has anyone found a better muffler for this unit? That is now the only issue I have, if it runs...

Thanks.


Chumley
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Old 09-20-2015, 10:14 AM   #9
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Re: Let's talk about diesel generators

Quote:
Originally Posted by llamadave

The only problem we have had with the generator was when we ran out of fuel when the tank got below 3/8 full (thinking we could use it until 1/4 full). After filling the tank, the generator would start but the rpms would cycle up and down every 10 or 20 seconds. We soon learned that air in the fuel line caused this and we had to bleed the injector. This is not difficult after learning how. Use a 17 mm wrench to loosen the nut on the stainless fuel line leading to the injector, near the bottom of the opening on the rear of the generator. Loosen it just slightly, have someone start the generator, then close it after cranking for about 5 seconds. You may have to do this more than once.

I am not sure but I think a poor calibration on the fuel gauge caused it to read high after a lot of use by our diesel furnace. I mean to do some tests on that but have not gotten around to it.
I noted what I think is a new option in the 2016 Sprinter Handbook for "Fuel Gauge, Optimized for Aux. Fuel Tap." (J51) which might provide insight into how the fuel gauge reading is calculated.

Description follows:

"In the standard specification, the fuel level display in the instrument cluster is controlled solely by the fuel consumption as calculated by the on-board computer. The level is only reconciled with the fuel level sensor in the tank and corrected when refueling is detected.

With this code, the fuel level display in the instrument cluster is reprogrammed so that it is solely controlled by the fuel level sensor in the tank, and shows the approximate amount of fuel remaining in the tank."
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Old 09-20-2015, 09:45 PM   #10
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Re: Let's talk about diesel generators

Quote:
Originally Posted by adstewart91

I noted what I think is a new option in the 2016 Sprinter Handbook for "Fuel Gauge, Optimized for Aux. Fuel Tap." (J51) which might provide insight into how the fuel gauge reading is calculated.

Description follows:

"In the standard specification, the fuel level display in the instrument cluster is controlled solely by the fuel consumption as calculated by the on-board computer. The level is only reconciled with the fuel level sensor in the tank and corrected when refueling is detected.

With this code, the fuel level display in the instrument cluster is reprogrammed so that it is solely controlled by the fuel level sensor in the tank, and shows the approximate amount of fuel remaining in the tank."

I meant to add (bad cut and paste on my part) that it would be interesting to know if M.B. could re-program (or has re-programmed) pre-2016 Sprinters to be optimized for the Aux. Fuel Tap in this way. Certainly, this option would not have been just added to the 2016 line up if it were not being sought out--one would think.

Regardless, the J51 option is probably worthy to look into for anyone ordering a 2016 who has plans on using the Aux. Fuel Tap for any purpose.
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