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Author Topic: inverter use with out genset  (Read 3914 times)
1960eagle
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« on: February 23, 2010, 06:25:30 PM »

Greetings all.Wonder if anyone has any exp with what i am considering?  I am thinking about using battery bank system to power inverter and using bus alt to charge battery bank.as the alt output is rated at 250 amp max,i would only need part of that.anyone doing this on there ride?I want to be able to run all of the 120 volt items 2 roof airs/fridge/tv. from what i have figured out it would appear that i would need a total inverter rating of 8k. I dont want to have a genset and would plug into shore power when parked.      thanks.     great to see the snow here in Austin tx today.now ready for spring!                                   
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luvrbus
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« Reply #1 on: February 23, 2010, 07:01:34 PM »

One problem you are going to have is with the Eagle being 12v you would need 2 sets of stacked inverters for a total of 4 and inverters you can stack are not cheap.
When you price those inverters a generator is probably going to be cheaper and without the headaches of the giant battery bank for power to run 8k worth of inverters because a 250 amp alternator is not going to keep up.  



good luck
« Last Edit: February 23, 2010, 07:09:19 PM by luvrbus » Logged

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1960eagle
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« Reply #2 on: February 23, 2010, 07:09:06 PM »

the reasons i was wanting to get away from genset was to conserve fuel and have less noise.&one less engine to worry about/lol. do  you know anyone who has used the set up i am thinking about?  thanks.
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« Reply #3 on: February 23, 2010, 07:13:58 PM »

No I do not know anyone using that type system  maybe Sean can give you some advice on the setup but me I would not even want to try it JMO 

good luck
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« Reply #4 on: February 23, 2010, 07:18:02 PM »

I know someone who was setting up 16 golf cart batteries in the spare tire compartment of an MC9 to be able to run the AC overnight in silence.

You have to love doing battery maintenance...

You will need to burn more fuel to spin the alternator on the coach engine, there's no free lunch.

No matter where you get it from, the same amount of work has to be done to recharge your battery bank.

Get onto the internet and get a shopping list of the components and wiring, then get a list of the materials needed for a sound box for a suitable generator.

Your $$$ will show you the way.

happy coaching!
buswarrior
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« Reply #5 on: February 23, 2010, 07:29:46 PM »

Hey 60Eagle,

Are you going to the New Texas Rally March5,6,7, in Franklin, Tx.? It's about 70 miles from Austin. You can get alot of info at the rally. You also have a new nut (wayneswirld2) in north Austin that just got his bus.

Richard
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« Reply #6 on: February 23, 2010, 07:52:04 PM »

For that much capacity while in motion, I would echo Cliffords advice about going with a genset.

Consider:  8000 Watts / 12 Volts = 667 Amps.  Add 10% for losses, that's 733 Amps.  If you run the system at half load on average, the engine alternator will not be able to keep up.

But, if you still wanted to do it anyway, I suppose you could divide up the systems, use multiple inverters,  battery banks and alternators.  Perhaps two 4000W inverters, each with its own battery bank and 250 Amp alternator.   At half load average that would be sustainable and with enough batteries it could withstand brief heavy loads when the compressors kick in or if someone wanted to make coffee while underway, etc.

It won't be cheap and as BW pointed out you will be using horsepower from the engine.  That will consume additional fuel and detract from available horsepower to the drive train.
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1960eagle
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« Reply #7 on: February 23, 2010, 07:56:48 PM »

Hello richard.I want to go to that rally,look forward to meeting some of the folks and seeing some really cool buses.didnt know there was a busnut so close to me,look forward to talking with him.are you attending the rally in texas in march?  
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rdbishop
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« Reply #8 on: February 23, 2010, 08:01:54 PM »

I'll be there. I live in New Braunfels, South I-35 mile marker 187.

Richard
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1960eagle
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« Reply #9 on: February 23, 2010, 08:11:16 PM »

Richard.look forward to meeting you and seeing all the buses there at the rally.i live in bastrop so not to far away.    Noel.
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rdbishop
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« Reply #10 on: February 23, 2010, 08:20:10 PM »

Noel,

Are you bringing your bus?

Richard
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1960eagle
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« Reply #11 on: February 23, 2010, 08:26:57 PM »

Richard,will not be bringing the bus.i am in the process of doing the tearout of the old conversion inside and wont be done by the time of the rally.and the tires are not really road worthy.been looking for a set of 11r24.5 tires/wheels if you know of a good source would like to know.    Noel
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TomC
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« Reply #12 on: February 23, 2010, 09:45:51 PM »

Personally- I think of the inverter as a standby intermittent source of electricity.  For instance, my inverter powers one of the two water heaters (to have hot water during driving time), the bathroom heater, T.V's, stereo's, microwave, toaster oven, and misc plugs.  Not powered through the inverter is the three roof top A/C's, the other water heater, refrigerator and freezer (both are 120vac/12vdc), washer/dryer. 
The amount of batteries you'll need will weigh as much as a generator.  Fuel savings will be offset by the cost of constant replacement of the batteries, the double cost of the two inverters. 
I have 2-8D Lifeline AGM's that easily get me through 24 hours of refrigerator and misc running.  I run the generator for a couple of hours in the morning and evening (just to make sure) when I'm dry camping.  I would encourage you to rethink your theory of not using a generator.  Good Luck, TomC
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« Reply #13 on: February 24, 2010, 06:18:06 AM »

One option would be to add a large 24 volt alternator like a 50DN just for house.  I would advocate for a generator instead of using the bus alternator, but this is an option.  This would allow for use of a larger inverter.
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« Reply #14 on: February 24, 2010, 06:35:16 AM »

I have been thinking of why not do a similar thing - but way smaller in scale.  Even then the costs don't add up very well.  I have a 24 volt bus system, and the 50DN, and all I want to do is run the single 15Kbtu AC while driving.  I figure 3K watt inverter would do it, and maybe 1800 watt constant load with the AC on full tilt.  That's around 70 amps,  about what the condenser motor took, and I could maybe use that relay to power the inverter.  But I don't think there is any reasonable way to get 8,000 watts out of a normal bus electrical system, and certainly not a 12 volt one.

Brian
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wayneswirld2
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« Reply #15 on: February 24, 2010, 07:00:07 AM »

Hey Noel, welcome to the insanity.  Like you, I'm new to this, but it sounds like you have much more experience with busses than I do!  I tend to agree with the rest of the guys here, stick with a generator.

Wayne
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« Reply #16 on: February 24, 2010, 07:49:50 AM »

Yep,
Sounds like a sub-station on wheels.
Dennis
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JackConrad
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« Reply #17 on: February 24, 2010, 11:22:52 AM »

What percentage of the time you are spending in the bus will the bus engine be running.  For us, it is less than 10% . The rest we are sitting someplace camping, frequently dry camping. That is why we have a generator.  Jack
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« Reply #18 on: February 24, 2010, 04:49:32 PM »

Welcome!

I can't add to what already has been said. However it'll be nice to meet you at the rally in a few days!

We have a genset and no battery bank, but we're hooked up to a pole 99% of the time. The other 1% we use the genset while on the road for needed A/C or whatever else my wife needs. Wink

Paul
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1960eagle
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« Reply #19 on: February 24, 2010, 07:20:44 PM »

Thanks for all the input,will think over and decide what i am going to do.look forward to meeting those who will be at the rally.     Thanks.
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Sean
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« Reply #20 on: February 24, 2010, 11:21:22 PM »

We do this all the time.  However, we have an extremely efficient coach, an enormous battery bank, and a 6,500 watt alternator.  Even then, we can only run two air conditioners at a time.

We also have a generator, but we never run it when we drive, only while parked.  If you are really serious about only ever parking where there is a power outlet, you might be able to get away without a generator, but that seems an ambitious goal -- power outlets can be mighty hard to come by in many parts of the country.

In any case, your 3,500 watt alternator is definitely not enough.  That would run maybe one single air conditioner (about 1,700 watts while running; more to start), your fridge, and some miscellaneous stuff.  Anything more than that, and you will be constantly depleting the batteries while you drive.

BTW, 8kW of inverters is impractical on a 12 volt coach.  Some high-end 24-volt conversions have this much capacity (twin 4024s).  We have a single 4kW unit, and it is more than capable of running the two air conditioners plus all the miscellaneous stuff, however, we use a DC fridge.  The sheer size and number of cables you'd need to draw 8kW at 12 volts is daunting.

The only way to really know how much you will need and whether it is possible is to do the math.  Don't forget to account for efficiency losses, which are in the 10%-15% range for DC-AC conversion, and in the 20% range for battery storage and retrieval.  I suspect that if you plan carefully, you can get the total demand down into the 5kW range, and then you can use a pair of stacked 2,500-watt inverters.  You'd still need to add about again as much alternator capacity as you already have; unfortunately, in a 12-volt application, that will mean a second alternator.  They don't come much bigger than 3,600 watts.

HTH,

-Sean
http://OurOdyssey.BlogSpot.com
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