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Chad&Jen

780 Generator Install

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We recently purchased a HF Predator 3500 generator and our plan is to install it below the passenger's side cab of our 780.  For any of you that have done a Volvo genny install, I'd love to hear about lessons learned and any tips & tricks.  I'd like to build as much flexibility as possible into the install including using an external 6 gallon gas tank and enabling the addition of a conversion kit to use 30/40# propane tanks sometime in the future.  Currently the target location is a large open space behind the passenger's side body panel, so all the brackets and supports would need to be fabricated from scratch. 

The fabrication seems to be the easy part of the project versus getting the genny successfully hooked into the truck's electrical system.  I'm leaving all of this to professionals, but just want to be educated about what's possible/safe/recommended.  Ideally, we'd like to power the interior lights/fridge/microwave and 110 outlets without having to idle the truck.  For A/C, we're considering a small 8K BTU portable unit that could store in the passenger's side closet and mounting the exhaust hose out of the passenger's window when in use (will likely require modifications as the truck window isn't square like in a house).  The unit would be plugged into one of the 110 outlets.  The units we've looked at max out at less than 7 amps, so the genny should easily be able to handle the load.

If I've missed something (highly likely) or am going down a road that ends in blue smoke and tears, please feel free to offer guidance.  We'd like to use the truck without a trailer in the near-term, hence the project.  Thanks in advance for any assistance.

  

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I carried a small 30amp portable in the space you listed for years. I'm on the process of installing an diesel Onan on my truck that is too big for that space. I'll convert that to storage I guess if I can find a water tight case/container to put there. 

Pictures here.

I'm just curious why you didn't go with a diesel generator? I know I did mine because that portable generator was a gimme, and I knew it wasn't permanent. Your post mentions adding a 6 gallon gas tank but you could run a diesel genset for days if you attached it to your trucks fuel tanks. There are several small enough to fit in the space you are looking at that could easily supply 30 amps to your trailer too. That is probably the route I would have eventually gone if I hadn't run into the deal of a lifetime on the commercial 7.5 Onan QD. 

I will say this, mounting a portable in that space you can expect it to get REAL nasty and dirty. I also vibrated the wheels right off mine...literally.

 

Edited by Big5er

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Considered diesel, but the HF was on sale, so price was a part of the decision.  Also we're not full-timers yet, so the genny may sit for weeks or even months between uses and I was told diesels need to be run regularly to avoid issues.  As for grime, I have a custom cover for the unit that should provide at least a little protection.

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15 minutes ago, DesertMiner said:

Do you plan on running the genny while it is under the fairing?  Yes

What about the exhaust?  Plan on attaching flexible metal hose to route exhaust towards the back of the truck under the bed

Cooling air? The area under the cab is not constricted and hopefully should provide adequate ventilation

Noise and vibration? Genny is rated at 57db, but time will tell if noise is an issue.  Considering rubber mounts to reduce vibration if needed.

There are some nice generator slide trays that might work.  Trays look like they would work well.  Will have to look into price.

https://www.morryde.com/products/93-utility-sliding-trays?return=%2Fproduct-category%2F2-sliding-trays%3F

 

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If your truck has an enclosed bed routing the exhaust under it is not a good idea.     Depending on how the generator is mounted the reflected noise could be an issue next to another vehicle or object.    Propane is a great fuel for small engines that don't run daily, if you use gasoline use ethanol free fuel.     As far as exhaust, look on youtube, there are several folks that use small cherry bomb type mufflers with good results on generators.

 

Steve 

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I don’t have fairings in the way, but here’s what I did.

1vPbSuVl.jpg

Wh6LaBbl.jpg

Gdttqahl.jpg

I haven’t got the wiring done to connect to the trailer yet. And really have no need for 110 in the cab.

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5 hours ago, rdickinson said:

Given my choices, I'd go with a 10k or 12k Onan and try to shoehorn it in the location you have in mind 

I don't think a 10 or 12k would fit behind the fairing and if it did you would have to do a lot of alteration to the truck, not just modify but alter the entire system that holds on the fairings. I wasnt willing to do that much alteration to try and fit my 7.5k in there.

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1 hour ago, Moresmoke said:

I don’t have fairings in the way, but here’s what I did.

Clean looking install. That's nice.

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Phil is right, the larger diesel gensets will not fit behind the fairing. 

There are a lot of compromises to be made putting a smaller gas portable behind the fairings. The previous posters have covered most of them.  Hooking power into the truck ranges from pretty simple, to very complex, depending on what you are trying to accomplish. If you are not doing it yourself, make sure you have someone that knows what they are doing perform the work for you. I've had had the "pleasure" of fixing a number of these  "endeavours".

Your biggest challenge on the generator will be keeping it  clean, and the amount of vibration it will put into the cab. Plus, keeping it cool can be a challenge if not done right. If you expect to use this much, and want convenience, then Phil's advice to do a small diesel genset is spot-on. If it is occasional use then your proposed solution is viable, but heavy users won't like it much.

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Many thanks for all the helpful feedback.  Roger described the space perfectly.  The truck does have regen, so everything needs to shifted slightly aft.  The dimensions of the genny are 22.75L x 17.3W x 20H, so I still think mounting it behind the flip-out fairing is doable with the front of the genny facing out.  For now, I'm going to move forward with the gas unit and will look at diesel options down the road.  

Here is a pic of the external tank configuration I'm considering.  If mounted above the genny, it appears to be a simple gravity feed system without the need for a pump. 

rsz_1s-l1600.jpg.d33ff119d27159d5d5d425fa774d8a3d.jpg

Here are rubber mounts that are also available which could help with the vibration issue.  

rsz_1rsz_1rsz_s-l1600_1.jpg.e9d159ca57c10d1be365028265de99b3.jpg

In regards to the electrical aspect, what pitfalls do I need to avoid?  As I said, I'm not going to be doing the work myself, but want to be able to better understand the specifics of what needs to be done in order for the genny to power most of the items inside the cab.

Thanks again, gentlemen.  Your assistance is invaluable.

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Something else to think about.  I'm not sure if you plan to do all or some of the work yourself but working under the truck is not easy.  A creeper works on smooth surface but everything you need to access is too high, too low, too far away because there ae sharp pointy obstacles in the way or too close so you can't work on it.  If that's not enough there are obstacles to fight with and reroute around or drill and go thru and last, maybe, there is nothing but deck above and no easy way to fasten to it.

 

Edited by rdickinson
info

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The Predator 3500 is already a fairly quiet generator. If it's for occasional use only, I'm not sure it needs much in the way of sound deadening. It's rated at 57 db, which is Honda territory. Mine is pretty quiet, but I think 57 db is a little optimistic. We can't hear it from inside the coach, but I imagine the neighbors will hear it just fine. Jay

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1 hour ago, Jaydrvr said:

The Predator 3500 is already a fairly quiet generator. If it's for occasional use only, I'm not sure it needs much in the way of sound deadening. It's rated at 57 db, which is Honda territory. Mine is pretty quiet, but I think 57 db is a little optimistic. We can't hear it from inside the coach, but I imagine the neighbors will hear it just fine. Jay

Jay,

This was a big part of why I went with the 3500.  Prior to the permanent install, my plan is to place the genny in it's final location and see the level of noise in the cab as well as how audible it is from around the truck.  This should give me a starting spot of how much sound deadening will be required.

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10 minutes ago, Chad&Jen said:

Jay,

This was a big part of why I went with the 3500.  Prior to the permanent install, my plan is to place the genny in it's final location and see the level of noise in the cab as well as how audible it is from around the truck.  This should give me a starting spot of how much sound deadening will be required.

If that's your only concern, I think the only thing to worry about is proper air flow for cooling the unit while it's running. Also, you might consider a permanent mount marine tank. I have an 18 permanent aluminum tank for my genset.

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I would ditch the gas tank now and go right to propane. I have an Onan propane genny in our truck and never worry about stale fuel and hard starts from gummy carb.

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On 6/12/2019 at 6:03 PM, Chad&Jen said:

Considered diesel, but the HF was on sale, so price was a part of the decision.  Also we're not full-timers yet, so the genny may sit for weeks or even months between uses and I was told diesels need to be run regularly to avoid issues.  As for grime, I have a custom cover for the unit that should provide at least a little protection.

 ".....so the genny may sit for weeks or even months between uses and I was told diesels need to be run regularly to avoid issues."

(IMO) The opposite is really the issue - unless you plan to drain the gas during the "weeks or months".  Otherwise plan on frequent carb cleanings.  Ethanol in gasoline is not your gen's friend!..☹️

.

 

Edited by Pappy Yokum

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I use an inverter generator powered by gas. I add Stabil to the fuel and when I am done with the generator, I simply shut the fuel off and run the gen until all the fuel in the carb is burned.  The fuel in the marine tank can then be used up in the lawn  tractor.  

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go propane from start if you are planning on doing that anyway. 

When my onan diesel died last summer and the cummins/onan folks couldn't even look at it for weeks and weeks, I borrowed my in-laws Hondas to get through the summer. twin 2000i with the parallel kit. Father in law converted them to propoane and I just strapped everything down on the deck. I did get a propane Y splitter so I could run both off the same tank. Worked good and kept 30a sunning down the road. Ran the AC in the sleeper and the fridge in the trailer. 

2iAnvCSl.jpg

worked really good with my ghetto portable AC unit in the sleeper with the exhaust port out the window (home depot special when the sleeper AC quit working).

 

 

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When I was looking at adding generator, we had a couple design criteria.  It had to be able to sit for almost a year and start right up (that means no gas gens), it has to be VERY quiet, it had to provide 240V as our dryer is 240, it had to last long enough that I would never have to replace it, be very difficult to steal, and later on I added it can't cost $10,000 or more.

So, I started down the 12kw Onan diesel path......that's when I added - it can't cost $10,000, so scratch that one.  I happened upon this Generac that is intended for off the grid cabins etc.  6kw propane, configurable for 240v, 500 hr oil change interval, and, at the time, $3200......score.  It gives me two 25 amp legs of 240v, -- it's happy with two A/Cs running, charging 800 ah battery bank, and other general loads.  Thought it would use a lot of propane so I set up the design to hold two #100 propane tanks, but never actually used anything larger than a #20 grill tank that last more than 4 hrs.

qGi366sl.jpg

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There is an aspect of propane that should be considered.     IF you have a small air cooled generator cold weather opps could be an issue.     Forklifts and equipment that run  on propane have water heated vaporizers and even with that running in very low temps below the teens can be challenging.     That is probably not an issue for general use, in an emergency situation that condition could exist.     That said I have no first hand knowledge of these small engine systems, the propane engines I have all use the forklift bottles that draw liquid not vapor.      I agree that for intermittent use propane is the fuel of choice.

 

Steve 

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5 hours ago, lockmup68 said:

go propane from start if you are planning on doing that anyway. 

When my onan diesel died last summer and the cummins/onan folks couldn't even look at it for weeks and weeks, I borrowed my in-laws Hondas to get through the summer. twin 2000i with the parallel kit. Father in law converted them to propoane and I just strapped everything down on the deck. I did get a propane Y splitter so I could run both off the same tank. Worked good and kept 30a sunning down the road. Ran the AC in the sleeper and the fridge in the trailer. 

2iAnvCSl.jpg

worked really good with my ghetto portable AC unit in the sleeper with the exhaust port out the window (home depot special when the sleeper AC quit working).

 

 

forgot pic of the Onan 8k diesel, sips from tanks and is very quiet. And it is working now! I think the 8k is quieter than the two Hondas. 

TzHC5S2l.jpg

 

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For vapour draw systems there are charts which show how large the tank needs to be for the “puddle” of liquid to supply vapour fast enough to supply the engine or appliance at various temperatures. A horizontal frame tank can supply more than a 12” diameter cylinder.

Edited by noteven
No pictures

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