Thinking about building a small Diesel DC powerplant

[James77MCI8]

What will be the final cost?

[bevans6]

I love this idea!  I have been trying to decide how to do my OTR AC system, as you all know, and I was really kind of irritated that I had to have two different AC power sources - generator and inverter.  This would let me run OTR with a DN-50 driven by the bus engine, and have a second DN-50 that could be the generator.

There are air cooled DN-50 kits available, or air cooled DN-50's, rated 270 amps.

Brian

[Sean]

Sean, Aside from starting the generator, would a battery be involved in your configuration?

Sorry, just realized this was addressed to me.

Yes -- if you use an automotive-style alternator, there must be at least a small battery (or maybe a large capacitor) in the circuit, otherwise there is a strong possibility of damaging the alternator -- see my hotly contested remarks in the other thread.

However, I am assuming the design intent here is actually to achieve battery charging anyway, so presumably there will be a fairly large bank involved.  This is really what this type of DC solution is best at -- recharging large battery banks.  For example, my AC-powered battery charger can put at most 150 amps into the batteries, no matter how big my generator or shore power is.  By contrast, a 50DN can put 270 amps into them, charging at nearly twice the rate.  Coupled with a properly rated engine, this is the most efficient engine-driven charging you can get, eliminating not only the limits but also the losses involved in first generating AC and then converting it to DC.

If you are planning on running a second alternator ... you will need to modify the regulation a bit.  Balmar has a special device called the "CenterFielder" which does this, but you can make one for peanuts with cube relays yourself too if you have the right circuit.

You're right, and I should have mentioned that when discussing pros and cons earlier.  Separate regulators (even one-wires) will work, but will not be optimally efficient, and one alternator will always be doing more work than the other (and thus get more wear and tear).

Several companies make multi-alternator regulators besides Balmar, including Ample Power and Xantrex.

While you're in there making your own power plant, think about water heating (using the coolant from the genny) ...

I would be careful with this one.  Being a belt and suspenders kind of guy, I am leery of any system that can disable all the prime movers on board at the same time.  Ideally I would suggest not only separate cooling systems, but also separate fuel supplies for the generator and the main engine.  This way, if you get stuck in the mud a hundred miles from help, you can generate power no matter what, even if one engine goes down.

So to implement what you suggest, I recommend using a heat exchanger to transfer waste heat from each engine to a separate hydronic loop for domestic heat and hot water.

-Sean
http://OurOdyssey.BlogSpot.com

[Kenny]

Remember this idea of using a 50DN is only going to get you 24vdc. You will then need Inverters to run any AC devices including air conditioning. Inverters aren't cheap.
Kenny

[Zeroclearance]

James my target is around $1000.00..    I have seen these alternators on Ebay, but I don't get the warm feeling about them.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=290331146760&viewitem=&sspagename=STRK%3AMEWAX%3AIT

I was going to purchase a used Kubota with 572 hours on it for $485.00, but with the new Yanmar Surplus engine, I will pay the extra to have a new engine.   I am trying to score my alternators, but can fall back to my spare belt driven 50DN..  That is proven power..   The oil scavenge system will require a higher mounting bracket.

Brian, the air-cooled kit is around $850 my cost.  

[Zeroclearance]

Sean, would your views change if you ran the HOT coolant out of the engine into a marine hot water heater with the coolant loop designed for this?   And them pass the loop into a temperature controlled radiator fan system.  

Kenny,  I mentioned earlier that I have 2 SW4024's..     DC power is a choice.   I want to invest in Solar panels, but this is a nice cheap addition.

[HB of CJ]

I'm assuming (dangerous word) that the engine is water cooled and runs at a fairly high rpm level.  Using the proper radiator and drive pullies will solve these problems.

Vibration?  Possibly curable through proper rubber mounts and noise insulation.  The electronic interface requirements I have no idea upon.  Dunno fur sures.

Designing and fabricating the proper inclosure (fire, sound, mounts) should be straight forward.  Might be best to have a dedicated fuel tank toos.

What is the durability/warranty of the Yahmar mill?  Be careful here.  Hear that lots of look-a-likes are coming out of China or India that don't work/last soss good.

Is there a alternative?  We toyed with an BIG alternator running off the tranny's top PTO (RTO 910 Roadranger) running thru a good regulator running the roof A/Cs...

...while running down the road thus saving having to use the main APU.  Just an alternate idea that won't work sitting under some trees somewhere parked.  HB of CJ (old coot) now.....bussless

[Zeroclearance]

HB, the rated RPM max HP is around 3600 RPM's but that isn't where peak torque is..   I would run it lower at 2400-2500 RPM's.  If you look at the link that I provided the unit does have a nice engine mounted muffler.

Yes there are clones made from China but this is the real deal Yanmar.   Yanmar make a very good small diesel.  Infact John Deere uses them in there small tractors from 12HP to 60HP.  

Everything is going to be belt driven.  I'm going to use 6 or 8 rib serpentine belt with a tensioner.   On could also have a idler pully added for around $26.00 to stabilize the belt.

I have thought similar to what you mentioned with the addition of a small fuel tank.   

[Tim Strommen]

Tim, for my bus I have 2 Trace 4024's running two separate battery banks and I'm all electric.   If you look at my avatar my bus is BLACK..   5 Tons of A/C cools the bus.   Right now I have installed a 50DN on my series 60,  this runs with the factory installed Bosch T1 and a factory installed 12V Leece/Neville.

Yeah, I saw the black bus – sexy, sleek, mysterious... Prevost H3-45?

For A/C, if you're going to have the genny running, why not use a Red-Dot A/C with the compressor spun by the crank on the small genny?  This will be more efficient, since you won't be converting energy after combustion from mechanical-to-electrical(DC)-to-chemical-to-electrical(DC)-to-electrical(AC)-to-mechanical.  Nick B. may be able to chime in here - I think a roof air can be relatively easily modified to utilize a second/third compressor, and an automotive AC compressor can easily be controlled by a remote relay (it turns on/off the clutch, just like in a car).

While you're in there making your own power plant, think about water heating (using the coolant from the genny) ...

I would be careful with this one.  Being a belt and suspenders kind of guy, I am leery of any system that can disable all the prime movers on board at the same time.  Ideally I would suggest not only separate cooling systems, but also separate fuel supplies for the generator and the main engine.  This way, if you get stuck in the mud a hundred miles from help, you can generate power no matter what, even if one engine goes down.

So to implement what you suggest, I recommend using a heat exchanger to transfer waste heat from each engine to a separate hydronic loop for domestic heat and hot water.

I agree with Sean, and in fact. you’ll find we agree on most things.  I’d offer as a rule of thumb, always use a heat exchanger between major cooling/heating systems to prevent total loss of collant.  For things like generating domestic hot water, I also suggest using a marine type water heater that has a double walled heat exchanger loop for added safety should there be a leak.

If you do the additional Air system charging and A/C, make sure the whole thing is set up as a "system", with proper check valves and sequencing – for instance, you don’t want a secondary air compressor to bypass the air dryer...

Safety should be the top bullet point on your system, with reliability being second, then parts avialability, then functionality, etc...

-Tim

[Zeroclearance]

No roof airs are planned.   Yes, I have thought about the RedDot systems..   That would be the logical route.   There are some night heavy duty compact compressor out there.   I don't know the HP draws vs RPM.   A 200amp 24 volt Leese alternator and 5 ton automotive style A/C compressor would most likely max out his engine.

[rv_safetyman]

OK, as long as we are playing with this concept, consider that a 24 Volt DC generator makes a great welder!  A 400 amp unit could sure burn some rod.  I still have my Popular Mechanics article (well over 40 years old) that tells how to build an engine driven welder using surplus aircraft generators. 

Someone mentioned aux. air supply.  I have brought up the thought of adding a York type AC compressor to my generator as an air compressor.  That is a very popular project for the off-road folks.  For more information on that concept look here:  http://www.kilbyenterprises.com/compressors.htm

Also, a couple of you seemed to touch on engine bearing loading.  I suspect that the crank and bearings are not designed for heavy side loading.  You could minimize the impact of this loading by using as large of a belt pulley on the crank as possible, and using a spring loaded idler in the belt drive.  Without going in to a lot of detail, the spring loaded idler makes the tension in the drive proportional to the power being transmitted.  That way, you do not need to tension the belt for the max HP.  Indeed, a very light spring force on an idler system can transmit huge amounts of power.  Spring loaded idlers are a belt's best friend.

Jim

[Ednj]

Here read this Old post =
http://www.busconversions.com/bbs/index.php?topic=4150.msg38213#msg38213
 

[Sean]

Sean, would your views change if you ran the HOT coolant out of the engine into a marine hot water heater with the coolant loop designed for this?  

Sorry, been off line for a few hours, driving.  I think this has been answered but let me say that, yes, you should use a marine water heater, with, as Tim suggests, the now-standard (and mandatory) double-wall exchanger.  But I would still recommend using a heat exchanger and a separate hydronic loop to do this.  Among other things, it will allow you to heat the hydronic loop from other sources, such as yet another heat exchanger from the main engine (and we actually generate most of our domestic heat and hot water this way, so don't underestimate the value of this), and/or a diesel-fired boiler such as a Webasto or Espar.

I agree with Sean, and in fact. you’ll find we agree on most things.

Thank goodness someone does.  I was beginning to think I was starting to lose it...

Remember this idea of using a 50DN is only going to get you 24vdc. You will then need Inverters to run any AC devices including air conditioning. Inverters aren't cheap.

Of course, this is where the thread started, and I see Kevin has already answered you.  But for those following along, this is a major topic that I cover lightly in my electrical seminars and more heavily in the bus conversion workshop (should we ever do one of those).

Simply put, if you live in your rig full-time and spend most of that time, or even a majority of it, away from the power pole, then using this method is far and away cheaper in the long run than a 120-VAC generator and no inverter.

I can go into a line-by-line breakdown of why this is true, but this is probably not the thread for it.  Perhaps it is a subject I can cover in a future BCM article.  In a nutshell, though, the reasoning is that the more actually drawn watts a generator is producing, the more cost-efficient that generator's operation will be.  With a DC generator feeding a large battery bank, every watt the generator is capable of producing is being used 80% of the time, and the other 20% it will be averaging about half load or so.

So the pay-back on the generator itself is much faster, and easily makes up for the cost of inverters.  The big cost item in this scheme, BTW, is actually batteries, which do get "used up" in the process and need to be replaced periodically, and figuring that part of the equation is actually where the math gets harder.

For rigs that are only used occasionally, such as weekend trips or the occasional week or two of camping, it's probably cheaper just to run a generator whenever you need 120VAC.  Where the balance point is, as they say, is left as an exercise for the reader.

-Sean
http://OurOdyssey.BlogSpot.com

[DMoedave]

Bill Glenn had an wvo fired set up in his bus and i always wanted to check it out more. I believe he had automotive a/c compressor running on his unit also for down the road air conditioning. Here on Long Island is a shop Sailon Electric that does incredible things for the ambulance and firetrucks that need lots of dc and or ac power at idle. Paul and his dad are amazing. So are Yanmar engines, but the older i lung units could shake rattle and roll. I was thinking long and hard about an APU truck unit for awhile for the driver air and heat etc. Good postings

[TomC]

I don't like two cylinder engines since they are basically a 4 cylinder with two cylinders lopped off.  They are not even firing.  Try looking for a small 3 cylinder-much smoother and quieter.
Instead of the giant 50DN (100lbs worth), look for the new Delco 270 amp alternator that is air cooled.  You could run two since you're not worrying about synchronizing the two since it is DC power.  Then you'd have a bit of redundancy with two smaller instead of one big alternator.  Good Luck, TomC