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Author Topic: Genset.  (Read 6162 times)
Bob Gil
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« Reply #45 on: March 11, 2008, 11:56:47 AM »

If you are talking to me I assume it is all 12 volt as it has two batteries and the ground on them go to the fram and the pos on each goes seprately to the starter and it starts very easly.  I figure if it were 24 they would be wired together and it would not start very well the way it is wired now.

I hope I am correct.
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Fort Worth, Texas where GOD is so close you don't even need a phone!

1968 GM Bus of unknown model 6V53 engine (aftermarket) converted with house hold items.

Had small engine fire and had no 12 volt system at time of purchase. 
Coach is all 110 w 14KW diesel genrator
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« Reply #46 on: March 11, 2008, 08:19:41 PM »

Fellow up here had built the space for 16 golf cart batteries in the spare tire compartment of an MC9.

Last I saw it, many years ago, he had 8 installed, with the other 8 to come.

He hated generator noise, and could run the one roof air in the rear bedroom no problem overnight on the batteries.

The trick is, starting with the coach cool, then the AC will cycle?

Celebrate the differences!!!

happy coaching!
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« Reply #47 on: March 12, 2008, 07:35:10 AM »

I have noticed some talk about remote radiators on the gensets. It would seem to me that if your unit was self-contained (all in one box) , you would need to open some kind of vents into your bay to allow proper air flow. (Get out the sawzaw? Shocked ) Before I bought  my bus, I was looking at a mc-8, that was for sale locally, and noticed a bay door that looked like it had been shot full of holes at a rifle range. I thought ,what is the meaning of this?....  I opened the door and saw what looked like a car engine (genset...)  bolted to the floor of the bay. I was shocked at the wanton destruction of the bus bay. Not only had they drilled 50 holes in the door but they also cut two giant three-sided cutouts in the floor and bent down the metal to make whopping air scoops for the genset. Is this necessary? I wouldn't want to trash my bay in this manner. How do we handle the necessary cooling air requirements in an enclosed bay?
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« Reply #48 on: March 12, 2008, 08:01:11 AM »

My genset requires fresh air for the engine along with some air movement over the engine.

In addition, my genset radiator which I have mounted remotely, requires a fan that can more at least 2500 CFM of air through it.  Sounds like maybe those people did not spend much time on design, and just did it, requiring mods later to keep it cool enough.  It does sound like a butcher job, and there are other ways to do it.
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« Reply #49 on: March 12, 2008, 08:20:26 AM »

My genset requires fresh air for the engine along with some air movement over the engine.

In addition, my genset radiator which I have mounted remotely, requires a fan that can more at least 2500 CFM of air through it.  Sounds like maybe those people did not spend much time on design, and just did it, requiring mods later to keep it cool enough.  It does sound like a butcher job, and there are other ways to do it.

I'm all ears Grin
Where is your radiator? Does your fresh engine air (assuming you have remote radiator) require cutting open your bay? Give me some proven locations for this in a mc-9 with otr air and heat. Please?
Thanks.
« Last Edit: March 12, 2008, 08:23:51 AM by chazwood » Logged

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Len Silva
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« Reply #50 on: March 12, 2008, 08:27:36 AM »

I have noticed some talk about remote radiators on the gensets. It would seem to me that if your unit was self-contained (all in one box) , you would need to open some kind of vents into your bay to allow proper air flow. (Get out the sawzaw? Shocked ) Before I bought  my bus, I was looking at a mc-8, that was for sale locally, and noticed a bay door that looked like it had been shot full of holes at a rifle range. I thought ,what is the meaning of this?....  I opened the door and saw what looked like a car engine (genset...)  bolted to the floor of the bay. I was shocked at the wanton destruction of the bus bay. Not only had they drilled 50 holes in the door but they also cut two giant three-sided cutouts in the floor and bent down the metal to make whopping air scoops for the genset. Is this necessary? I wouldn't want to trash my bay in this manner. How do we handle the necessary cooling air requirements in an enclosed bay?
You have to get a lot of air into and out of both the radiator (remote or self contained) and the genset itself.  With careful planning, you can have both the air supply(s) and returns in the bottom of the bay and spare the doors.  You must be careful not to short circuit the supply so that you don't re-intake hot exhaust air and the exhaust must not be so powerful and directed straight down that it stirs up clouds of dust and dirt. Also, be sure that the tires don't throw water up into the intake.  Both the supply and exhaust air should go through some baffles and turns for noise reduction.  I would also remote the engine air intake so it is getting cooler air.
With a remote radiator, I would use a sail switch for an alarm or put it in the shut down circuit in case your blower fails.

FWIW,
Len
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« Reply #51 on: March 12, 2008, 08:35:12 AM »

Since I have a transit with no real baggage compartments, I made my gen compartment in a hole that was next to the drivers seat.  It mounts like a front engine, the compartment is even with the raised drivers seat.  But the compartment is tight.  With using a Powertech 10kw with 4 cylinder Kubota, it required I remote mount, the air cleaner, radiator, and muffler outside the box.  I made the box with a 1/4" steel floor with 2" angle iron bolted to the perimeter.  I mounted 3/4 plywood for the sides (Dick Wright at Wrico knows of a really dead plywood for noise suppression) and lined the walls and top with 1" foam lead insulation (really effective).  The only real bummer is that the generator had to be mounted from the front side door inside, and the only access is through the trap door on top of the generator from inside next to the driver's seat (got to do weird stuff sometimes).  I made my own remote blower out of a Grainger 9" squirrel cage blower that can take 150 degree air with single inlet.  I mounted the radiator to the inlet side of the blower, and with a 1/2hp 2 spd enclosed fan cooled ball bearing motor, mounted it under the drivers seat with the radiator facing forward and the exhaust for the blower out the left side through a cut hole in the skirt.  I use two speeds-high for during the day and low for quiet night time use.  It works well. The only time it couldn't keep up is when I stopped for a break in 107 degree weather and had all three A/C's on.  I imagine the pavement was up around 150 degrees it slowly heated up. Just turned off one of the A/C's and it was all right.  But going down the road its' fine.
For ventilating the cabinet, I have a 8" bathroom axial flow blower that can get wet mounted in the front left corner with a small rectangular hole at the left front radius for fresh frontal air.  This 8" is branched to 2-6" hoses that blows the fresh air directly onto alternator end of the radiator (the genset is mounted backwards as compared to a car engine).  It then exits the rear of the gen cabinet through 2-6" hoses that are covered with screens to keep the little critters out.  Has worked well for 600 hours (like 24,000mile worth-40mph is the conversion).  It works so well, will probably use the same system again.  Good Luck, TomC
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« Reply #52 on: March 12, 2008, 09:19:38 AM »

I guess my point about inverters was not clear.  It's not that I don't see their value or their potential need, it's that it seems to be a common thought that you have to have one.   And that the reason to have one is to not run the genset because you need to not run the genset.  I don't buy that logic, and not having a big inverter works fine for me under my usage profile.  However, I will agree that if you are camping at places that limit generator usage, then you have no choice, but be prepared, it is going to be expensive, and those batteries do require periodic servicing and replacing.  Just be sure you are aware of what you are getting into.  I think that most people will agree that you need a genset and if you want a quiet/reliable/powerful one it is going to be costly.  If you can get away with it, based on your usage profile, why spend alot more money on batteries and inverters to not run the genset you spent alot of money on.

As for the efficiency comment, I wish I had 450 hp to steal a couple dozen from!   Huh 
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« Reply #53 on: March 12, 2008, 10:40:53 AM »

... be prepared, it is going to be expensive, and those batteries do require periodic servicing and replacing.  ...  If you can get away with it, based on your usage profile, why spend alot more money on batteries and inverters to not run the genset you spent alot of money on.


As I said, it does all depend on how you use your bus.  But to respond to these last comments on the economics, let me just say that our inverter and battery bank have already paid for themselves.

We paid about $3,000 for our inverter and original battery bank, and I have since replaced the bank at a cost of about $2,400, for a total of $5,400.  You need to deduct from that number at least something for whatever minimal house batteries and charger or converter you would need anyway to run whatever low voltage stuff you have, unless you have a straight 120-VAC coach (hard to do if you want things like roof vent fans and a decent water pump).  So let's call it $5k even.

By contrast, my generator costs me about $4 per hour to run.  (That's total costs, not just fuel.  You need to figure oil and filter changes, valve jobs, top end rebuilds every so many hours, total lifetime and replacement costs, etc.).  That number was probably closer to $3 when we hit the road (lower fuel prices), so call it $3.50 on average.

When we are parked long-term in temperate climates, we run the generator a total of about an hour per day.  If we had no inverter at all, that number would increase to at least 2-3 hours per day. When we are parked in hot climates, where air conditioning is needed 24/7, we run the generator about half time.  With no inverter, we'd have to run it full time.  And lastly, when we drive every day or two, we usually don't have to run the generator at all, whereas with no inverter, we'd be back to the 2-3 hours per day.

Since I have not kept careful track of how many days we drive versus park, or how many days were hot versus temperate, it's hard to be precise.  But clearly the inverter and batteries have reduced my generator run time by no less than half, and could be as much as 80%.  Let's say it is about one third what it would be without the inverter.

Since hitting the road, we've put 1,100 hours on the generator.  Without the inverter, then, I would have put around 3,300 hours on it.  Those extra 2,200 hours would have cost me $7,700.  So my $5k investment in inverter technology has already saved me $2,700 in three years, and those savings will only continue to increase over time.  Bottom line:  the inverter was "free," with a payback of less than three years.

The savings are actually much higher than that, because the inverter allows us to go places that we otherwise could not go without spending ~$30 per night for a campground.

The analysis comes out much differently, of course, if you only use your coach part time.  But it is never cut and dried, slam-dunk -- you need to do the math.  Only then can you answer your own question: "Why spend a lot more money on batteries and inverters to not run the genset you spent a lot of money on?"

-Sean
http://OurOdyssey.BlogSpot.com
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« Reply #54 on: March 12, 2008, 02:21:21 PM »

While I will admit I have not done the research, and thus those numbers could be completely accurate, I really can't imagine that 2,200 hours of genset run time will cost 7,700 dollars.  At full load my 8kW genset uses 0.5 gal/hour.  Even at $4 a gal that is $4,400 in fuel cost, leaving $3,300 in maintence costs for 2,200 hours?  That seems a bit high. 

Also, if you spent $3k on inverter and batteries, and then spent another $2400 on replacment batteries, then either you got a great deal on the inverter or on the initial batteries.  I am never so lucky to get deals like that, so I always base my costs on retail costs.  When people talk about running 2 AC's on the road, the first thing that is always recommended is a SW4024, which is going to cost the average unlucky person at least $2500 plus $2400 in batteries for $4900 initial investment, and you have not driven an hour yet. 

As for running off inverter while driving, there is a cost to that, it is not free.  I agree that it will depend on your busses engine efficiency.  In my case, I get about 8 mpg, and at 60 mph that is 7.5 gal/hour.   If I am running my genset during that time, that would be a total of 8 gal/hr max.  That's is a 6.6% increase.   Now, let's guess that motoring down the road takes 200hp and running the inverter is going to take 10hp from the alternator, that is a 5% increase in load on the motor, not sure how that is going to affect mileage, but I am guessing alot of people would love to shave 5% load off their motor. 

I think we've beaten this enough I suppose, and I agree that evenones usage is unique, and that it will work both ways.  Just be sure you look at how you are going to use it, and where and when you want to spend your money.  One size does not fit all.
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« Reply #55 on: March 12, 2008, 03:13:07 PM »

...  At full load my 8kW genset uses 0.5 gal/hour.  Even at $4 a gal that is $4,400 in fuel cost, leaving $3,300 in maintence costs for 2,200 hours?  That seems a bit high.


As I said, these were my numbers, which, of course, will be different from anyone else's.  My generator burns about 1.1 gph at about 50% load.  That's high, I admit.  If I were to buy a generator today for this coach, I would have bought one in the 6-7.5k range, where I would expect the consumption to be more like yours.  However, when I did the math, it would have taken me ten years or more to pay back the cost of changing generators (the one we've got now, an older but massive 17kW unit, came with the bus).

The rest of the numbers break down to about $0.20 per hour for oil and filters, and roughly $0.50 per hour for rebuild/replacement costs (average of 20,000 hour life expectancy for a typical 1800rpm diesel generator, with $10,000 average rebuild/replace cost).  So add about 70 cents per hour to the hourly fuel cost, in my case about $3.70 or so, so I am actually at about $4.40 per hour to run the generator right now.  (BTW, we use this figure when deciding whether to pay for hookups -- if we'll need to run the genny for, say, four hours a day due to air conditioning needs or whatever, then suddenly a premium of $16 for electric hookups starts looking like a good deal.)

In your case, at half a gallon an hour, with today's fuel prices of ~$3.40 or so, you are looking at $2.40 per hour to run your generator.  That's a real-world number, but, of course, it's average.  Your generator could crap out long before 20k hours, or it could go for double that number without needing any major maintenance -- it's random (actually, a bell curve).

Quote
 
Also, if you spent $3k on inverter and batteries, and then spent another $2400 on replacment batteries, then either you got a great deal on the inverter or on the initial batteries.


I'll give you the actual figures.  I paid $1,800 for my SW4024, brand new.  You can certainly get them today for this price, I would not pay any more for one.  And I got a great deal on batteries that I knew would not live long (cheap Xantrex crap that had been sitting on someone's shelf for who knows how long, even though "new"), but at less than a grand for ~840 amp-hours (at 24 volts), it was a deal I could not pass up.  I got good use out of them, but there's a reason why I needed new batteries at only three years.  Many, many more details on this on my blog archive.

That deal no longer existed, of course, when I went to replace them.  I bought 920 amp-hours of Trojan AGMS for the $2,400 I mentioned.  Again, full details on the blog.

Quote
I am never so lucky to get deals like that, so I always base my costs on retail costs.  When people talk about running 2 AC's on the road, the first thing that is always recommended is a SW4024, which is going to cost the average unlucky person at least $2500 plus $2400 in batteries for $4900 initial investment, and you have not driven an hour yet.


As I said, I would not pay more than about $1,800 for a SW4024.  The "retail" price reflects an enormous markup, and the business is very competitive.  You may have to hunt around and/or bide your time (or accept a factory refurb, with 90-day warranty) to get this low a price, but $2,000 can be had easily.

Quote
As for running off inverter while driving, there is a cost to that, it is not free.  I agree that it will depend on your busses engine efficiency.  In my case, I get about 8 mpg, and at 60 mph that is 7.5 gal/hour.   If I am running my genset during that time, that would be a total of 8 gal/hr max.  That's is a 6.6% increase.   Now, let's guess that motoring down the road takes 200hp and running the inverter is going to take 10hp from the alternator, that is a 5% increase in load on the motor, not sure how that is going to affect mileage, but I am guessing alot of people would love to shave 5% load off their motor.


I've discussed this extensively in other posts.  It does, of course, depend on what engine you have and what kind of driving you do.  The ~10hp that the alternator will rob on level ground or going up hill will cost you about .1-.2 gph.  Even with your efficient 0.5gph genset, this is only 20-40% of that amount.  Also, drawing this power from the alternator will not change your main engine maintenance intervals, so the oil and filter component goes away, and it will probably have a much smaller effect on engine life expectancy than for the dedicated power plant.  All told, perhaps only a quarter of the cost per unit of energy than running the generator.

Remember also that all the power coming off the alternator is 100% free when going downgrade, so the numbers are actually better than this in "average" driving.

Quote
I think we've beaten this enough I suppose, and I agree that evenones usage is unique, and that it will work both ways.  Just be sure you look at how you are going to use it, and where and when you want to spend your money.  One size does not fit all.


Here, I could not agree with you more.  I was just trying to answer, for everyone's benefit, your comment about not understanding why people think they need inverters.  It's because, for the vast majority of us, it makes both economic and lifestyle sense.

I hope, by sharing my direct experience here, that people will be able to take a look at their own numbers and work through this to arrive at a more informed decision.

-Sean
http://OurOdyssey.BlogSpot.com
« Last Edit: March 12, 2008, 03:18:42 PM by Sean » Logged

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Bob Gil
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« Reply #56 on: March 12, 2008, 03:26:12 PM »

I have to agree that one thing will not work for every body.

More so when some of did not build them our selves and they were not build the best way in the first place.  I think that I have learned from this that there are things that i can do with what I inherited to make the best of it.

I figure if I can get an inverter to run the icebox while I am going down the road and maybe the TV I will be able to save on the genset some. and when it is hot i will need the genset.  I will add some 12 DC outlets in it as it does not have any at this time, there are a lot of things i run off of DC.

I may not be able to afford a full set of batteries when I first get it going since I figure I will not be using it more than once every other month.  I many just take the deep cycle batteries I have in the the suburban (I have 2) and the two I have in the pickup (I use them both and it keeps the batteries up pretty good.) along with the two in the buss.  I know they may not all be balanced but using them this way 4 days every other month may be better investment than buying new ones to set.

I hope every body else has better funds for their bus toys.  I am going to have to pay as I go and hope I can make it.  The wife is wanting to get it ready for vacation in June to Allentown PA and VA but I don't thin I can rush it that fast.  I think I want to do some short trips in it first, better to have problems worked out close to home. Smiley
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Fort Worth, Texas where GOD is so close you don't even need a phone!

1968 GM Bus of unknown model 6V53 engine (aftermarket) converted with house hold items.

Had small engine fire and had no 12 volt system at time of purchase. 
Coach is all 110 w 14KW diesel genrator
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« Reply #57 on: March 12, 2008, 06:15:54 PM »

I'm all ears Grin
Where is your radiator? Does your fresh engine air (assuming you have remote radiator) require cutting open your bay? Give me some proven locations for this in a mc-9 with otr air and heat. Please?
Thanks.

Here's how I ventilated my generator enclosure.  The hot air is exhausted through the floor of the bay.  I obviously still have a few things to do, but this seems to work well keeping the generator cool (enough). 

David
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« Reply #58 on: March 12, 2008, 06:57:46 PM »

David,


While that looks very professional..... I was hoping to avoid any serious mods to the bus metal. (not going to happen I suppose Sad)
« Last Edit: March 12, 2008, 07:25:13 PM by chazwood » Logged

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« Reply #59 on: March 12, 2008, 07:03:18 PM »

While that looks very professional..... I was hoping to avoid any serious mods to the bus metal. (not going to happen I suppose Sad)

The nice thing is that all I have to do is to replace the aluminum strip I cut and you wouldn't be able to tell that anything was ever done to the door.  You may be able to see where my bay door is damaged... I ran over a tree root.  I have to replace the panel anyway, so none of these minor mods are really an issue to me!

David
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