Generator Choices

[Aviator]

I'm at the point where I need to start gathering parts to get this project on the road

Background  its a 102C3 with the OTR air conditioning/heat still installed and functioning.

I've decided for parked air conditioning, I'm going to go down the mini-split road.

That tells me I need to be in the 8000-10000 watt generator range

To those of you who have installed a generator in the bays, tell me what you liked and what you'd change after living with the setup for a while.

I've been looking two generator choices

10KW PowerTech unit that's fully enclosed  Claimed to be 65dB at full load
9750KW Open frame unit  Claimed to be 70BD full load

Both have a Kubota Diesel   The Powertech unit comes in at $10,000 the Open frame unit at $6000

Pro's?  Con's?   Thoughts ??

I'm all ears

Larry

[bobofthenorth]

Think carefully about future service. You absolutely WILL need to work on this generator at some time. Oil filter, fuel filters, lift pump, air filter, any auto shutdown systems, starter - whatever is in an awkward place is the most likely to fail. I don't know where I come down on rollouts because they add a lot of complications for connections and soundproofing but if a rollout is an option then it's the way to go.

[belfert]

Check to see if the Powertech has brushes or is brushless.  I think they still have brushes.

I have a Powertech enclosed model with brushes and the brushes have been nothing but trouble.  I think I'm on my third or fourth set of brushes.  To be fair, some of the brush issues have been my fault.  I didn't leave enough room to access the end of the generator so the brushes had to be replaced mostly by feel.  I added a slide last year and knock on wood I have not any brush issues since then.  I wouldn't have had to replace the first set of brushes if they had a brushless head.

[Oonrahnjay]

   Briefly -- my opinions:

1)  Do some sharp-pencil math.  10K sounds a bit large for a mini-split or two.  You want to have your gen sized for your needs; too small and it runs right at full capacity (a recipe for disaster) and too large and it never gets a good load on it (ditto).  Or course, you need to size for all your needs.  If you plan to run your water heater on the gen or cook with electricity, etc., your loads will be bigger.  Consider everything and how much "load shedding" you're going to be doing.

2)  I have a steady-speed Onan 10K.  It's too big, I should have gone smaller.  My opinion is that a factory-enclosed unit is going to be much better for the "ordinary" guy; a person with good skills and specialist experience can build an enclosure, radiator setup, wiring arrangement, etc. with an "open" unit but the enclosure does it all for you -- and it right from the factory.  (This is not to knock anyone who has done it and done it successfully, but I didn't pay $10K for a generator to overheat it a few times experimenting on it.)

3)  In my opinion, money you spend to get a generator that's quieter is money well spent.  And don't forget, very little of gen noise is from the tailpipe (they all have excellent mufflers) -- most of your noise is going to be cooling air, radiator fans, and vibrations from mounting the frame mounts, radiator mounts, exhaust pipe mounts, etc. And - due to the logarithmic nature of sound energy - 72 dB is half the energy of 75 dB and absorbing or diffusing that energy is what you'll need to do get that thing quieter.

   Please understand that a lot of the above is my personal opinion.  Generators are very much NOT a one-size-fits-all item.  It's good to figure out exactly what you need and select the type of generator you want and the features that fit in with your projected usage.
   

[thomasinnv]

Very good point about the load on the generator being used. Also another thing to consider, though it may be lower on the list,  is the fuel economy. Too large of a generator and you're throwing away fuel. let's say for example the highest load the generator ever sees is 6kw. If you have a 15kw genset you're going to be wasting fuel even though you're running at less than half capacity. In that situation something in the 7.5 to 8kw range would be better. A little less fuel, less upfront cost for the generator, a little power left over "just in case", and the genny will not be running at full capacity constatly, which is not good.

Some will disagree with my philosophy on this and that's fine. I'm speaking from experience here. Btdt and gtts.

[luvrbus]

You have 2 generator suppliers that advertise here on this board give one of them a shot they are Wirco and EPS. Keep it mind the altitude and heat affect a generator here in the desert in 115 degree weather a 7.5kw will become a 5.5 in a hurry (read that from Cummins Onan) and will struggle running 2 AC units

.All the entertainer and the high end Prevost converters over size their generators  to compensate for different regions of the US I personally think you are on the right track go at least 1kw larger than required 2kw is better     

[eagle19952]

80% continuous is actually considered maxed out...
60% is ok...
less is where trouble comes quicker...sooner.
a little extra and you can throw out a 20 amp cord and help your neighbor... that's what i do

[Oonrahnjay]

    Agree completely with Thomas, Clifford and Don above. 

[Lee Bradley]

I am running a 24,000 BTU inverter mini-split. I have a 4,000 watt inverter that has no problem running that A/C system so I am thinking you could be a little high on your generator sizing. I have a Honda EV-6010 (no longer available new) that I use to recharge the batteries through the inverter with the inverter set to limit the generator load at 40 amps (80% of generator output). I run the generator long enough to charge the batteries or the bus alternator  charges the batteries while driving. The battery bank has no problem running the bedroom A/C 8 hours in 90 degree weather. Your results may vary depending on lots of things.

[Aviator]

Wow   I just love the wealth of knowledge here  YOU GUYS ROCK!!!


Luvrbus  PM me about the generator guys on the board,  I don't know where to find them.

Keep the info coming this is a great discussion and i'm already rethinking my setup


I've got mini-split questions next stay tuned!!!

Larry

[flynbanjo]

We have a Powertech 12KW enclosed unit that is mounted in the left forward bay.  We cut out all of the access holes that powertech recommended.  So far maintenace has not been an issue.  We also added some sound damping material inside the bay to help with the noise.  So far I wouldn't change a thing. 

[belfert]

We have a Powertech 12KW enclosed unit that is mounted in the left forward bay.  We cut out all of the access holes that powertech recommended.  So far maintenace has not been an issue.  We also added some sound damping material inside the bay to help with the noise.  So far I wouldn't change a thing. 

Have you had to service the generator end (the left side in the photo) yet?  It looks like you might you might have a few more inches on the left side than I do, but not really enough to easily work on it.  I have had to replace the brushes three or four times now and it is a major pain without enough space.  I finally added a slide last year and now I could probably replace the brushes in 30 minutes flat if I have to do it again.  I should replace the generator end bearing on mine next year.  I have the bearing, but haven't done the replacement yet.

Everybody says a brushless head is too long to fit in the cabinet so I live with what I have.

[flynbanjo]

Brian, we have not had the fun as of yet of replacing the brushes.  I should say we only have a lilttle over 500 hours on the unit.  I must admit I hadn't planned for such eventuality.  When we installed the generator, we first built a cart to be able to handle the generator around the shop and then slide it into the bay.  After reading your post, I kinda figure we would just slide the unit back onto the cart to replace the brushes then reinstall it into the bay.  I suspect the hardest part would be disconnecting the exhaust system.  Sounds like a simple plan, What could possibly go wrong?  I know famous last words.  Hopefully I can put this task off for a long, long while.   

[TomC]

Since I have a transit bus (AMGeneral)my generator set up is a little different. I made a generator compartment next to the driver's seat like a front engine (the generator engine faces back so the generator head fits under the dash floor.) I'm using an open Powertech 10kw of which they still make with the 4 cylinder Kubota and brushless alternator. I built a 1/4" thick steel floor with 1.5" angle iron around the perimeter to anchor the 3/4 plywood enclosure. Since the generator had to be installed through the front door, all servicing is done from inside, but from above the generator. With the 3/4" plywood enclosure, and 1" lead/foam sound insulation, you can't hear it running inside except for the vibration. When in the bedroom with the A/C on, you don't even notice the generator running.
I have a remote radiator with a single inlet squirrel cage blower belt driven off a 1/2hp 2spd fan cooled totally enclosed motor mounted under the driver's seat exhausting out the left side. High speed during the day, low speed for quiet night time. Also an 8" inline bathroom ventilator to push air through the enclosure.
I highly recommend using an open generator and also a remote radiator. On my truck I'm using a Wrico 12kw with 3 cylinder Kubota that Dick Wright custom made for me that's only 36" long. Dick sold me a fan that uses only 5amps that blows really hard, but with a speed controller for the radiator. Good Luck, TomC

[belfert]

Brian, we have not had the fun as of yet of replacing the brushes.  I should say we only have a lilttle over 500 hours on the unit.  I must admit I hadn't planned for such eventuality.  When we

I suspect the main reason I had to replace the brushes in the first place was because of running the generator in a dusty environment.  I go the Blackrock desert every year and we used to run the generator while generating clouds of dust driving in and out.  We no longer run the generator when driving in or out.  The brushes got stuck in the holder I suspect due to the dust.

You may never have to replace the brushes.  At some point you will need to replace the generator end bearing.  I believe the consensus is to do that around 1000 hours.  If the bearing seizes you will likely need a new head.