Author Topic: is a 6v92 capable of putting out 96 volts when driving?  (Read 12068 times)

Offline Sean

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Re: is a 6v92 capable of putting out 96 volts when driving?
« Reply #30 on: September 30, 2010, 09:48:00 AM »
Forgive me, Teresa, but I'm having trouble understanding why you'd want to do this.

Are you hoping to save money, fuel, or the environment?  Because I can assure you you will do none of these.

What you are proposing is complex, and will require many specialized modifications for which there is no standard support.  As such, the cost of doing this will be many times greater than the cost of a conventional coach electrical system plus conventional toad.

As for fuel and the environment, burning diesel to make electricity to charge a battery to power a toad will use more fuel than just having a combustion engine in the toad.  Even if you use, say, WVO to power the bus, you'd use less fuel overall by having a diesel toad with its own WVO system, with perhaps some pre-processing done on the bus.

In addition to more fuel being consumed overall, the environmental costs of the battery plant tend to significantly offset the minimal environmental savings of the electric drivetrain.  Remember that even when charging from the grid, the power is coming from fossil fuels, principally coal, albeit on a more efficient scale than local generation by internal combustion.

In short, it's a lot of work, money, and likely frustration for very little or perhaps no benefit at all.

I must also inject a bit of reality here.  By your own admission you know little about electricity, and yet this project requires engineering-level knowledge, far and above what is required to just install a house electrical system in a coach.  There are perhaps half a dozen or so of us on this board that could do this from scratch, and you've already heard from many of us.  While you might get answers to specific questions, and along the way pick up a great deal of knowledge yourself about the subject, it's not likely to be sufficient to build a complete, working, safe system.

To do this on your own by asking questions here also means you will get a system designed by committee.  If you are intent on doing this, my own suggestion would be to hire a competent engineer to take it from beginning to end -- you are far more likely to get an end result that works and is safe.

One last caution about proceeding with a project like this.  Once it's done, no one anywhere will be able to fix it except yourself.  You will also likely have many specialized parts that are not readily available.   You need to be prepared for the downtime that might be imposed by this.  For example, lets say you succeed in finding or making a 96-volt alternator and somehow connect it to your engine; if that alternator breaks, you could be sidelined for months waiting for a replacement.  Moreover, as a specialized one-off item, you will pay full price for any repair or replacement.  By contrast, a 24-volt coach alternator is a commodity item, and can easily be sourced new, rebuilt, or used at a variety of price points and in a matter of a day or two.

If you decide to move forward with this, I wish you the best of luck, and I will even be happy to answer questions and lend a hand.  But I want to make sure you go into this with eyes wide open.  I know that, while I myself could design such a system, I wouldn't even try, because the cost/benefit equation simply does not pencil out.

-Sean
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Offline RJ

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Re: is a 6v92 capable of putting out 96 volts when driving?
« Reply #31 on: September 30, 2010, 09:55:43 AM »
Teresa -

Personally, I believe in the KISS principle (and that doesn't mean Gene Simmons & Co!)

VW TDI's make great toads, btw.

FWIW & HTH. . .

 ;)
1992 Prevost XL Vantaré Conversion M1001907 8V92T/HT-755 (DDEC/ATEC)
2003 VW Jetta TDI Sportwagon "Towed"
Cheney WA (when home)

Offline Jeremy

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Re: is a 6v92 capable of putting out 96 volts when driving?
« Reply #32 on: September 30, 2010, 10:27:08 AM »
You guys are no fun.

Did the "cost/benefit equation pencil out" when American went to the Moon? No. Was it still a worthwhile thing to do? Yes.

I cannot speak for Teresa's motivations, but mine would be simply be the challenge of taking-on very interesting project, and creating something unique. I'd have thought most bus-nuts could relate to that.


Jeremy
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Offline Sam 4106

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Re: is a 6v92 capable of putting out 96 volts when driving?
« Reply #33 on: September 30, 2010, 11:21:50 AM »
Hi Sean,
I find your "cost/benefit" comment interesting in the context of this bus conversion board. I doubt that any of us, with the possible exception of you full timers, that could make the cost/benefit equation pencil out unless we put an unrealistically high value on the benefit side of the equation. I did a bus conversion and built our house for the sense of accomplishment and the learning experience, not because it was practical. I think that is what most hobbies involve. I have no doubt that you have done some of those types of projects yourself without thought of the cost/benefit equation and have derived a good deal of personal satisfaction from them. I would guess that volunteer work would also fall into that category. I do note that you were only stating your perspective and not telling Teresa not to do the project.
Thanks, Sam MC8
1976 MCI-8TA with 8V92 DDEC II and Allison HT740

Offline happycamperbrat

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Re: is a 6v92 capable of putting out 96 volts when driving?
« Reply #34 on: September 30, 2010, 11:42:13 AM »
Sean!! I knew you would jump in on this sooner or later  ;D Welcome!!

Yes I know it will be complicated and I have already been sourcing electronic engineers who are familiar with both RV house systems and EVs to hire (possibly you would want the job?) to do the paper work. They are not easy to find. Usually they are adept at one or the other, but not both. All I want is schematics and shopping lists and answer of questions from time to time, I will be doing all the physical work myself.

The reason I want to do it is because I live within 10 miles of my work and can charge both at home and at work. This would serve not only as a toad but as a daily driver. Im thinking the economics of it would work out well for my applications.

The many batteries I need to buy for my bus turned rv would mostly be sitting and aging (because I was designing a system where I would not use a generator). This approach gives dual purpose to the batteries during their lifespan as well as saving me gas money. My thoughts are to be able to charge the batteries thru the onboard VW controller/charger with both AC current and DC. Of course the DC would only charge the batteries while I was towing the VW so it should cost no more diesel then towing any other toad. Additionally, there is the possibility of solar panels which I wont get into at this time. As for saving the environment, there are a lot of arguments both ways about that on the web and I am by no means an expert so I will stay out of that one as well.

In the future I believe that the price of lithium batteries will come down and be much more affordable and we will be seeing a lot more electric vehicles on the road. I believe fossil fuel is going out in my lifetime.

The reason my brother makes the biodiesel for me is because I have found WVO to be impossible to get in California so I cannot rely on that to power a daily driver for me.

Where I live, our power plants provide electricity through windmills so I dont use fossil fuel or nuclear waste to get the electricity to recharge anything.

About the 96volt alternator, I found one rebuilt on ebay yesterday for $999.00 ....... I really dont know, but Im even thinking that maybe I could use multiple 24 volt alternators mounted in my engine to power the toad batteries?

Quote
If you decide to move forward with this, I wish you the best of luck, and I will even be happy to answer questions and lend a hand.  
Thank you!!!
The Little GTO is a 102" wide and 40' long 1983 GMC RTS II and my name is Teresa in case I forgot to sign my post

Offline happycamperbrat

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The Little GTO is a 102" wide and 40' long 1983 GMC RTS II and my name is Teresa in case I forgot to sign my post

Offline Sean

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Re: is a 6v92 capable of putting out 96 volts when driving?
« Reply #36 on: September 30, 2010, 09:52:03 PM »
...
Of course the DC would only charge the batteries while I was towing the VW so it should cost no more diesel then towing any other toad.
...

The power to charge the batteries in the toad is not free, it has to come from somewhere.  Your main engine will burn more fuel running your 96-volt alternator to charge the toad than it would to just tow.  You haven't said how many watts are needed to charge, but figure that every 6kW costs you ten engine HP, give or take.

Quote
...
Where I live, our power plants provide electricity through windmills so I dont use fossil fuel or nuclear waste to get the electricity to recharge anything.
...

That's a pleasant thought, but it does not work that way.

Your wind-farm provider is connected to the grid.  Like all grid-connected renewable plants, it operates at 100% of available production all the time (nuclear plants, too).  Virtually all demand power in the US comes from coal-fired plants.

So when you are using, say, 10 kW of power it may very well be coming from wind.  However, when you turn that 10 kW load off, the wind farm does not suddenly produce 10 kW less power; that 10 kW is merely sold to someone someplace else.  When you turn your 10 kW load back on, that other person now needs to get the 10kW he was using from someplace, and that someplace is a coal-fired plant.  It is an inescapable part of the calculus of North American grid power.  EVERY electric car on the road ultimately owes its power to a coal-fired plant if it is plugged into the grid.  That will remain true right up until the North American grid no longer uses coal plants to provide demand  power.  This is the dirty secret of zero-emission vehicles -- every one of them trades petroleum emissions at the point of use for coal emissions someplace else.

FWIW

-Sean
http://OurOdyssey.BlogSpot.com


Full-timing in a 1985 Neoplan Spaceliner since 2004.
Our blog: http://OurOdyssey.BlogSpot.com

Offline happycamperbrat

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Re: is a 6v92 capable of putting out 96 volts when driving?
« Reply #37 on: September 30, 2010, 10:00:02 PM »
Well I cant cure the world's problems. The best I can do is try to make as little impact as possible as I pass thru this world and pass it on to the next generation.
The Little GTO is a 102" wide and 40' long 1983 GMC RTS II and my name is Teresa in case I forgot to sign my post

Offline happycamperbrat

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Re: is a 6v92 capable of putting out 96 volts when driving?
« Reply #38 on: September 30, 2010, 10:04:56 PM »
Quote
The power to charge the batteries in the toad is not free, it has to come from somewhere.  Your main engine will burn more fuel running your 96-volt alternator to charge the toad than it would to just tow.  You haven't said how many watts are needed to charge, but figure that every 6kW costs you ten engine HP, give or take.

I dont know how many watts I need.  If the 96 volt alternator is not efficient enough then how about plugging the toad into a charger/pure sine wave inverter on the rv?
The Little GTO is a 102" wide and 40' long 1983 GMC RTS II and my name is Teresa in case I forgot to sign my post

Offline happycamperbrat

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Re: is a 6v92 capable of putting out 96 volts when driving?
« Reply #39 on: September 30, 2010, 10:09:24 PM »
I did find this too which specialises in ev systems for VWs http://www.e-volks.com/about.html
The Little GTO is a 102" wide and 40' long 1983 GMC RTS II and my name is Teresa in case I forgot to sign my post

Offline Sean

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Re: is a 6v92 capable of putting out 96 volts when driving?
« Reply #40 on: September 30, 2010, 10:24:14 PM »
Well I cant cure the world's problems. The best I can do is try to make as little impact as possible as I pass thru this world and pass it on to the next generation.

I applaud you for that.  Again, I just want you to go into this with the facts, and you should be aware that the global resource impact of what you are proposing may, in fact, be greater than more traditional methods.  It might be less, too, but it's nearly impossible to calculate.

If you charge the car with grid power at both ends, things are more clear-cut.  Grid power is generated much more cleanly and efficiently than you can produce it, either with an alternator on your main engine or with a generator.  It's also much less expensive, per kW.  But your original question was not about using grid power, but rather using the bus to charge the car.  Very different math between those two options, both from a cost perspective as well as an environmental one.

It's certainly an interesting project, if having an interesting project is the goal, as others have suggested.  I had the impression you were thinking this is going to save fuel or money, and I think that is unlikely, just by doing a quick back-of-the-envelope.  That is, of course, JMO, and I've been wrong before.  You need to do the math for yourself to know if it will achieve your own objectives.

-Sean
http://OurOdyssey.BlogSpot.com
Full-timing in a 1985 Neoplan Spaceliner since 2004.
Our blog: http://OurOdyssey.BlogSpot.com

Offline happycamperbrat

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Re: is a 6v92 capable of putting out 96 volts when driving?
« Reply #41 on: September 30, 2010, 10:32:56 PM »
I do think it will save money and that is one of the reasons for doing this. I think that it would pencil out better then what I was planning before which was just to buy a HUGE bank of batteries and cover my roof with as many solar panels as possible in order to keep from using the generator. I only camp a few times a year, all those batteries would be sitting and aging while I wasnt camping. This way I can use the same amount of batteries (around a dozen or so 6volts) and have them serve double duty during their life span plus not spend money on gasoline for the toad aka my daily driver (not to mention I wont have to worry about oil changes, anti freeze or maintaining those types of systems)...... I dont understand how this could possibly not pencil out for me unless you were thinking I was only going to have a few batteries and a big generator on my rv with gas in my toad like most people because that was never what I wanted to do.
The Little GTO is a 102" wide and 40' long 1983 GMC RTS II and my name is Teresa in case I forgot to sign my post

Offline happycamperbrat

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Re: is a 6v92 capable of putting out 96 volts when driving?
« Reply #42 on: September 30, 2010, 10:42:09 PM »
By doing this I am even starting to embrace my generator and not thinking about selling it anymore. I will have that stinky, noisey obnoxious thing in my toad.... when boondocking in the rv with the toad hooked up to it, the generator could be on and be in a GREAT soundbox! Additionally, if I am out sight seeing in a different town I am not familiar with and get lost or something and need an emergency charge to get back to camp THEN I will be VERY thankful I have the loud stinky obnoxious generator.
The Little GTO is a 102" wide and 40' long 1983 GMC RTS II and my name is Teresa in case I forgot to sign my post

Offline Sean

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Re: is a 6v92 capable of putting out 96 volts when driving?
« Reply #43 on: September 30, 2010, 10:44:42 PM »
I dont know how many watts I need.  If the 96 volt alternator is not efficient enough then how about plugging the toad into a charger/pure sine wave inverter on the rv?

Actually, direct DC at the proper voltage, as you originally proposed, is the most efficient.  But not free.  As an example I can say that my own alternator uses about a quart of fuel per hour (over and above whatever is used to move the bus) to charge the batteries at a rate of about 5 kW.  That's still way more efficient than running the generator to do it, though, and of course it's free when descending steep grades.

Knowing how many watts you will need is key to figuring out whether this is even do-able.  For example, one of the car systems you linked to requires a 5kWH battery system for a range of, IIRC, 30 miles.  A standard bus alternator can produce that much energy in just an hour, although in practice it takes longer than that to achieve a full charge.  By contrast, a charger which could run on a standard household outlet would require nearly three hours to deliver that same amount of energy.

-Sean
http://OurOdyssey.BlogSpot.com
Full-timing in a 1985 Neoplan Spaceliner since 2004.
Our blog: http://OurOdyssey.BlogSpot.com

Offline happycamperbrat

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Re: is a 6v92 capable of putting out 96 volts when driving?
« Reply #44 on: September 30, 2010, 10:55:40 PM »
Thanks Sean for that post!! I really appreciate it!

In planning the ev what I need is actually probably minimal. The VW bus weighs about 3000 lbs empty and as I recall the recommended max weight is 5000 lbs. I dont know how much the gasoline engine and fuel tank weigh, so when they are removed it will weigh less. Myself, mom, children and dogs who will ride in it all together weigh about 500 - 600 lbs (the higher if hauling groceries as well). I would like to cruise mostly at 20-40mph but with occassional 50mph. Im within 10 miles of work and can charge up there or at home. I live and work on flat land in a valley. When traveling with the rv I will be in various terains though. I would like to be able to drive about 40-50 miles at average speed without needing a charge, and of course I dont want to run my batteries down more then 50%
The Little GTO is a 102" wide and 40' long 1983 GMC RTS II and my name is Teresa in case I forgot to sign my post

 

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