As not to hijack gr8njt's thread I'll start a new one. From what I gather you can run your inverter continuously off of an alternator! This turns on some light bulbs in my head(very dim) Why would anybody spend the big money for gensets when you can do this?
Here's a few questions about this set up.
1. can you run your inverter that much safely?
2. Can you produce 220 volts?
3. How big of alternator would you need?
4. how big of motor to drive alternator?
5. How inexpensively can you build something like this?
6. could you set it up to turn on automatically when battery voltage gets down to 50%
7. do I sound stupid?
Capt. Ron,
Hay, I see a bulb lit in your camp....
What did you have in mind for a source of engine?
Bill Glenn [homegrowndiesel] has a setup like you are thinking. 12v generator.. He has a great system but, the engine is a little loud.
Nick-
Ron, why not use the inverter output to run an AC motor to drive the alternator to charge the battery to run the inverter to run the AC motor to run the alternator to run the inverter to run the AC motor to run the alternator.
Richard
Quote from: captain ron on January 23, 2007, 07:51:41 PM
As not to hijack gr8njt's thread I'll start a new one. From what I gather you can run your inverter continuously off of an alternator! This turns on some light bulbs in my head(very dim) Why would anybody spend the big money for gensets when you can do this?
Here's a few questions about this set up.
1. can you run your inverter that much safely?
2. Can you produce 220 volts?
3. How big of alternator would you need?
4. how big of motor to drive alternator?
5. How inexpensively can you build something like this?
6. could you set it up to turn on automatically when battery voltage gets down to 50%
7. do I sound stupid?
Quote from: DrivingMissLazy on January 23, 2007, 08:04:56 PM
Ron, why not use the inverter output to run an AC motor to drive the alternator to charge the battery to run the inverter to run the AC motor to run the alternator to run the inverter to run the AC motor to run the alternator.
Richard
Trust me I already thought of that ;D ;D ;D ;D ;D ;D perpetual power
Well, I tried ;D ;D ;D
Richard
Quote from: captain ron on January 23, 2007, 08:12:28 PM
Quote from: DrivingMissLazy on January 23, 2007, 08:04:56 PM
Ron, why not use the inverter output to run an AC motor to drive the alternator to charge the battery to run the inverter to run the AC motor to run the alternator to run the inverter to run the AC motor to run the alternator.
Richard
Trust me I already thought of that ;D ;D ;D ;D ;D ;D perpetual power
Capt Ron,
You do not sound stupid. It's a good idea that can be taken forward and improved upon.
I've read about these home made gensets a while back in 1999 fearing the arrival of Y2K
I do not know if this link (http://theepicenter.com/tow052903.htm) will help you brighten up that lightbulb but this site (http://theepicenter.com/tow052903.htm) have detailed instructions on how to built one with readily available supplies. If you scroll to the bottom of that page, they have cheap prices for parts needed to put a project together.
Good luck!
Ron,
How about this for a 240V inverter?
http://www.affordable-solar.com/sma.sunny.boy.6000u.inverter.htm
or one of these:
http://www.sunpowercorp.com/inverters/
or this:
http://www.donrowe.com/inverters/aims_3000_240V.html
There are lots of different inverters out there.
Cap'n,
That's just how some of the variable speed generators such as the Onan Quietdiesel work. An alternator rectified to DC, powering an inverter.
Len
Just looking at the inverts Dallas listed:
The first two use DC voltages in excess of 100 volts and the last one is 12 VDC but you would need 500 ADC for the 6000 watt output.
Quote from: Lee Bradley on January 24, 2007, 08:36:37 AM
Just looking at the inverts Dallas listed:
The first two use DC voltages in excess of 100 volts and the last one is 12 VDC but you would need 500 ADC for the 6000 watt output.
I only posted those as ideas to go by. I left the actual finding of the inverter that would work for each individuals application up to the student.
However, looking at the one, (and several others that require high VDC), if you think about it, 240V DC isn't that hard to come up with. that would be 20 12V batteries, plus the amp draw is only 25A.
With the last one, needing to draw 500a DC is that much out of line with what you draw on a large 120V inverter.
All it takes is thinking outside the box instead of blindly following in the footsteps of everyone else. After all, isn't that why we've chosen bus conversion as a hobby?
Dallas
Way back when my father-in-law built a alternator to maintain his house batteries when on Ham Radio field adventures. It was a single wire alternator hooked to a 3hp Briggs and Stratton engine. A small base, two pulleys and a belt. It is still around somewhere.
Might take some research or experimenting to see how big an engine vs how many amp alternator vs gearing. I suppose that without too much thought a manual controlled regulator could be designed to limit engine load.
Not arguing just listing requirements, those high DC voltages are not usual for buses but anything can be done. As for the 500 amp load that is just a fact of life when you run a big inverter off 12 volts.
I built hundreds of inverter systems for the UPS industry. The DC bus voltage was either 300 volts or 600 volts DC. For sure you did not want to stick a screwdriver across those terminals. LOL
Richard
Ever since I have been driving I have had a morbid and irrational fear of being stranded with flat batteries - so I'm liking this idea of having another way of charging batteries should my generator fail (and potentially a much faster way of charging too). I also like the whole 'inventiveness' thing, and definitely disagree with those who say 'You must do it this way because everyone else does'.
What would be a really neat solution perhaps would be to arrange the additional small engine so that it could somehow be made to turn the existing bus alternator, rather than having to supply a new alternator and all the associated cables and switching etc required. It wouldn't really be feasible to change belts over each time, but I expect a clever person could work out some kind of electrical clutch mechanism to allow the alternator to be turned by either engine. Perhaps the electric clutch thingy off a belt-driven air conditioning pump could be adapted?
Jeremy
It might be more reliable and a lot quieter to use one of the smaller Yamaha or Honda generators. You could then power a charger for the batteries. It might be more economical than having to run a big genset just to charge the batteries. Of course, you'd have to have gasoline on the bus, but some of us do anyway.
David
in 50+ years of RV'ing I only had an alternator on a vehicle quit one time. At the next town I stopped at Sears and purchased a small battery charger. I then started my genset and connected the battery charger to the coach battery so I had lights and the other needed electrical items. I did not have an inverter. In fact this was before the days of the inverter. I did always carry the battery charger after that, but never needed it. This was on a gasoline coach. A diesel coach requires very little DC power to keep running.
Richard
Quote from: Jeremy on January 24, 2007, 10:52:15 AM
Ever since I have been driving I have had a morbid and irrational fear of being stranded with flat batteries - so I'm liking this idea of having another way of charging batteries should my generator fail (and potentially a much faster way of charging too). I also like the whole 'inventiveness' thing, and definitely disagree with those who say 'You must do it this way because everyone else does'.
What would be a really neat solution perhaps would be to arrange the additional small engine so that it could somehow be made to turn the existing bus alternator, rather than having to supply a new alternator and all the associated cables and switching etc required. It wouldn't really be feasible to change belts over each time, but I expect a clever person could work out some kind of electrical clutch mechanism to allow the alternator to be turned by either engine. Perhaps the electric clutch thingy off a belt-driven air conditioning pump could be adapted?
Jeremy
Quote from: DavidInWilmNC on January 24, 2007, 11:14:56 AM
It might be more reliable and a lot quieter to use one of the smaller Yamaha or Honda generators. You could then power a charger for the batteries. It might be more economical than having to run a big genset just to charge the batteries. Of course, you'd have to have gasoline on the bus, but some of us do anyway.
David
And now we've gone Full circle! :D :D :o :o
The Honda and I think the Yamaha use inverter technology to create electricity. Which means, if your batteries go flat, you crank up a small engine to run an alternator to run an inverter to run a battery charger to charge the batteries so the engine will start and run the alternator to charge the batteries to run the stuff in the coach and they'll go flat again so you start all over! ::) ::) ::) ::)
How about getting really basic and buying one of those war surplus Organ Grinder type generators that you crank by hand for hours and hours and hours to charge your batteries so you can start the generator to run the inverter to charge the batteries to start your main engine to run all the stuff.....
Wow, charging batteries is a hard job to think about.
I have a 24 volt electrodyne alternator I bought off of E-bay 2 or 3 years ago. It was a new rebuild from detroits city transit. I don't know the specs on it as far as amp's, some of you may. I also have a brand new Honda generator remote starter. My inverter is 12 volt and I have no intentions of changing that, works fine. Can I use all of this stuff to build a cool genset or should I put it on E-bay and start over? Don't know if there's a way to rectify,capacitate, modulate or just reduce voltage. Those other 3 words were just thrown in there to impress you guy ;D
It all depends. I assume your coach is 24 volts and you have and existing alternator on it to charge the coach batteries. I assume your house batteries are 12 volt. Although the electrodyne is available in different amp ratings, I really do not see how you can use it to maintain your 12 volt house batteries. I have no idea what the Honda remote starter is. Just a remote start panel?
I would guess you would be better off, since you now are an educated electrician, to dump this stuff on ebay and get what you really need which I again assume is a 120 volt genset.
Richard
Quote from: captain ron on January 24, 2007, 12:06:47 PM
I have a 24 volt electrodyne alternator I bought off of E-bay 2 or 3 years ago. It was a new rebuild from detroits city transit. I don't know the specs on it as far as amp's, some of you may. I also have a brand new Honda generator remote starter. My inverter is 12 volt and I have no intentions of changing that, works fine. Can I use all of this stuff to build a cool genset or should I put it on E-bay and start over? Don't know if there's a way to rectify,capacitate, modulate or just reduce voltage. Those other 3 words were just thrown in there to impress you guy ;D
Quote from: DrivingMissLazy on January 24, 2007, 11:25:06 AM
in 50+ years of RV'ing I only had an alternator on a vehicle quit one time. At the next town I stopped at Sears and purchased a small battery charger. I then started my genset and connected the battery charger to the coach battery so I had lights and the other needed electrical items. I did not have an inverter. In fact this was before the days of the inverter. I did always carry the battery charger after that, but never needed it. This was on a gasoline coach. A diesel coach requires very little DC power to keep running.
Richard
When I said 'generator fail', I meant generator, not alternator. If I have flat batteries the only way I can start the engine is to charge the batteries up - and should the generator (or charger) fail I cannot do that - and even if everything works the charging would take quite a while. That's why I like the concept of an additional level of redundancy and and alternative way of producing power in an emergency.
Jeremy
Well I'll NEVER be an electrician but I'll always be a tinkerer of sorts with making things and trying to do something original and different.
My ultimate idea for my genset since my bus is Harley Davidson themed, Was to get a motor from the Harley V-Rod and mount it in the place I removed ac condenser. Hook it to a generator head using a HD belt. It's water cooled and quiet, has plenty of horse power and also has an alternator that could be upgraded to a heavier duty one four touring packages to do battery charging. I know it would be economically unfeasible to build but would be way cool and that's what a lot of us are looking for. And if I ever get the opportunity to do this I will..............Oh the Honda remote starter is the panel and wiring harness. Don't know if it would be adaptable to anything else or not ????
Ron, the first thing I think you need to do is learn the difference between a generator and alternator, if you do not already know that.
Basically what we are discussing, I believe is a device for charging either a 24 volt or 12 volt battery. If that is correct, then an alternator is a newer invented device than a generator but they both do the same thing. Put a 12 (24) volt charge into a set of batteries.
The generator generates DC directly and outputs DC thru a set of very heavy duty brushes to the load.
The alternator generates AC which feeds thru a set of rectifiers (diodes) which converts the AC to DC and then outputs a DC voltage to the load.Alternators were invented in the late 60's and have been standard equipment on all automotive products since that general era.
An engine genset is typically an engine driving an AC alternator and outputting 120 volts at 60 hertz.
Based on the above, we need to know what you really want to do.
Richard
Richard,
The automotive alternator was developed long before the 60's.
I've seen refences to them clear back into the 40's, and the PD4104 had what was called an AC generator inthe 50's.
Just a little worthless trivia from my coffee and 12v clouded mind.
:-*
Your making this more difficult (for me) than it needs to be. My understanding when I started this thread was that you could make a generator of sorts using an alternator and just charge your batteries to keep up with the demand on them from the inverter. eliminating the need for a large, expensive, and loud generator. I already have a coleman 3500 generator that does the job when called upon. I however cannot use my smart charger off of it as it has already burned up 2 of them. Just not compatible. I may build one of these just for fun and something to do and the learning experience.
Now my previous post about building a genset out of a V-Rod motor was my ultimate goal when the bus is complete. Correct me if I'm wrong but after reading the thread about the 24 volt alternator I thought I could do both things and have redundancy built into this unit. Just for example only... I buy that generator head from Northern Tool. Drive it with the V-Rod motor to make my regular genset.
Then I use the built in alternator to keep my house batteries charged. You can get heavy duty alternators for them to help with the larger load, which still may not be enough to keep up with a running load, but it would not need to since if its running any way your running the generator also, unless you build in a disengage device. It probably don't make sense to any of you but I think it would be way cool. The Ultimate Harley Bus
No matter what anyone else thinks, I think it's cool, Ron.
My plan is to use inverter technology and an Isuzu motor from a Carrier or Thermoking reefer unit. It'll take up a whole bunch less room than my old Generac contraption. I also plan on mounting 2 Leece-Neville truck alternators on it to run 2 seperate inverters. After all, why not, If the little motor has to run, it needs to be run under a load anyway, why not make that load as heavy as possible?
YMMV
Thanks Dallas, If I had Money I'd be a dangerous man. I have a very creative (weird) mind.
No way. The silicon diode was not invented until the 50-60's and the brushless alternator was not possible without the diode. Prior to that time all the devices generated the DC directly and removed it from the revolving armature with the aid of very heavy DC brushes riding on commutator bars.
AC generators (not alternators) prior to that time used heavy duty brushes riding on sliprings.
Richard
Quote from: Dallas on January 24, 2007, 01:50:18 PM
Richard,
The automotive alternator was developed long before the 60's.
I've seen refences to them clear back into the 40's, and the PD4104 had what was called an AC generator inthe 50's.
Just a little worthless trivia from my coffee and 12v clouded mind.
:-*
Sounds to me like it would work. Just be aware that the Northern alternator is 3600 rpm, extremely noisy and very poor voltage regulation. At least the ones I have seen.
Richard
Quote from: captain ron on January 24, 2007, 02:02:47 PM
Your making this more difficult (for me) than it needs to be. My understanding when I started this thread was that you could make a generator of sorts using an alternator and just charge your batteries to keep up with the demand on them from the inverter. eliminating the need for a large, expensive, and loud generator. I already have a coleman 3500 generator that does the job when called upon. I however cannot use my smart charger off of it as it has already burned up 2 of them. Just not compatible. I may build one of these just for fun and something to do and the learning experience.
Now my previous post about building a genset out of a V-Rod motor was my ultimate goal when the bus is complete. Correct me if I'm wrong but after reading the thread about the 24 volt alternator I thought I could do both things and have redundancy built into this unit. Just for example only... I buy that generator head from Northern Tool. Drive it with the V-Rod motor to make my regular genset.
Then I use the built in alternator to keep my house batteries charged. You can get heavy duty alternators for them to help with the larger load, which still may not be enough to keep up with a running load, but it would not need to since if its running any way your running the generator also, unless you build in a disengage device. It probably don't make sense to any of you but I think it would be way cool. The Ultimate Harley Bus
Quote from: captain ron on January 24, 2007, 02:02:47 PM
Just for example only... I buy that generator head from Northern Tool.
Only used that one as on example.
Quote from: DrivingMissLazy on January 24, 2007, 05:11:03 PM
No way. The silicon diode was not invented until the 50-60's and the brushless alternator was not possible without the diode. Prior to that time all the devices generated the DC directly and removed it from the revolving armature with the aid of very heavy DC brushes riding on commutator bars.
AC generators (not alternators) prior to that time used heavy duty brushes riding on sliprings.
Richard
Quote from: Dallas on January 24, 2007, 01:50:18 PM
Richard,
The automotive alternator was developed long before the 60's.
I've seen refences to them clear back into the 40's, and the PD4104 had what was called an AC generator inthe 50's.
Just a little worthless trivia from my coffee and 12v clouded mind.
:-*
Here's an excerpt from the 4104 supplement X-5914:
I do not know the date of the supplement, but the 4104 was built until 1960. In my statement I said in the 50's 0r 60's. I know that in my 53 model 4104 it was a generator. Sometime then according to what you posted the silicon diode and transistors were developed in the 50's for commercial use and the alternator was developed.
The first computer ever built I saw in 1954 (Philco Geniac) and it was still all vacuum tubes. Therefore I still stick to my statement made in the earlier post: The silicon diode was not invented until the 50-60's and the brushless alternator was not possible without the diode.
Richard
As an aside - I previously verified that the most efficient conversion from AC to DC was by using a full wave rectifier resulting in a 30% +/- inefficiency - FWIW
I was in electronic school in 1956 when the school received a germanium signal transistor from RCA Labs along with a blurb of how these would revolutionize electronics. I repaired quite few voltage regulators for buses, and still in the 70s they were using germanium transistors that were only available from a small after market company who had them custom made. Likewise, the front wheel driven speedometer that MCI was still using on the MC-7 (1973) was all germanium transistors. I was using power diodes (20 amp) before 1960 which I suspect were germanium because more than half were reject because of low back resistance and very large heat sinks.
The development of the silicon junction after that time did revolutionize, not only electronics, but the entire world.
I worked on one 1960 4104 and it incorporated quite a few things (including an alternator) that had been developed for the 4106.
Niles: Do you have a reference for those numbers of 30% efficiency. I find it hard to believe that a 270 amp, 28 volt alternator would be radiatiing over 5 kilowatts of heat from the diode plates when it is running. With that kind of efficiency, you coud use an air cooled alternator to heat your bus with the hot air. Since the diode plates are insulated from the case and have no colling fins, I doubt that they radiate more heat than a 100 watt light bulb.
I also would like to see that. My belief is that they are over 99% efficient.
Richard
Quote from: niles500 on January 24, 2007, 11:12:07 PM
As an aside - I previously verified that the most efficient conversion from AC to DC was by using a full wave rectifier resulting in a 30% +/- inefficiency - FWIW
Sorry I was wrong - its 81.2% - I must have been confusing it with another application
the math is on the following link - HTH
http://72.14.203.104/search?q=cache:OosJkJDnq40J:www.visionics.ee/curriculum/Experiments/FW%2520Rectifier/Full%2520Wave%2520Rectifier1.html+full+wave+rectifier&hl=en&gl=us&ct=clnk&cd=5
OK. That is the efficiency of the complete AC to DC circuit including the transformers and other components. I suspect the loss across the diodes is less than 1%. I am still surprised that the overall conversion efficiency is that low though.
Richard
Quote from: niles500 on January 25, 2007, 01:53:03 PM
Sorry I was wrong - its 81.2% - I must have been confusing it with another application
the math is on the following link - HTH
http://72.14.203.104/search?q=cache:OosJkJDnq40J:www.visionics.ee/curriculum/Experiments/FW%2520Rectifier/Full%2520Wave%2520Rectifier1.html+full+wave+rectifier&hl=en&gl=us&ct=clnk&cd=5
On a silicon diode rectifier, the only loss is the voltage drop across the diode junction. This is nominally .5 volts on an ordinary silicon diode like we are using. On a three phase full wave bridge rectifier this loss occurs across two diodes for each phase. One volt of loss on a 28 volt alternator represents 3.5% of the voltage but since the loss occurs at the peak of the waveform where thee is very little arrea under the curve, the actual total power loss (p in/p out) will be less than the 3.5%
Nothing in this world is 100% efficient so any other component that you introduce into the circuit will introduce more losses and they all multipy in series. This is the big advantage of the three phase rectifier in that no other components are required to get a DC voltage higher than the RMS voltage of the AC input, without having to add a ton of capacitance.
Quote from: captain ron on January 24, 2007, 02:02:47 PM
...Your making this more difficult (for me) than it needs to be.... My understanding when I started this thread was that you could make a generator of sorts using an alternator and just charge your batteries to keep up with the demand on them from the inverter. eliminating the need for a large, expensive, and loud generator. I already have a coleman 3500 generator that does the job when called upon. I however cannot use my smart charger off of it as it has already burned up 2 of them. Just not compatible. I may build one of these just for fun and something to do and the learning experience....
Quote from: Dallas on January 24, 2007, 02:13:19 PM
No matter what anyone else thinks, I think it's cool, Ron.
My plan is to use inverter technology and an Isuzu motor from a Carrier or Thermoking reefer unit. It'll take up a whole bunch less room than my old Generac contraption. I also plan on mounting 2 Leece-Neville truck alternators on it to run 2 seperate inverters. After all, why not, If the little motor has to run, it needs to be run under a load anyway, why not make that load as heavy as possible?
Hey Ron,
Your idea is totally valid. Take a look at the small Honda generators, the new hybrid-drive systems in use, and the diesel-electric locomotives that the majority of railroads use.
On smaller generators - a small microprocessor can control the speed of the engine to create enough power out of the generator (rectified alternator) to fit the demand of the load - the DC is then inverted to AC for consumption. This is the type of method is used in the little Honda inverter generators.
For hybrid-drive systems, they use a smaller engine and a battery/ultra-capacitor bank to store power when the drive train load is not high. Then, when the load is increased, the batteries/ultra-capacitors dump their stored power into the drive system to augment the power created by the prime-mover (this allows the use of a smaller prime mover to overcome the "average" load - not the "peak" load a direct drive vehicle needs to support). When the load is near-or-at "No-Load" for a given time, most new hybrid drives will shut down the diesel to save fuel (and will run from the batteries until they reach a low level). Diesel-electric locomotives are run about the same way - except there is no mechanical connection to the drive wheels from the diesel.
Back when I was toying with the electric fan replacement concept (which worked somewhat - but not to my satisfaction), the idea was to have a second power pack to run the house and maintain the chassis electrical (and take over for the prime-mover alternator when on hills etc.).
I quoted Dallas' comment as he has hit the efficiency nail on the head. If you are going to be running a secondary engine - you'll want to try to snatch as much energy out of that engine as possible. Electricity is okay, might as well throw on an air compressor to keep the chassis aired-up, and heck why waste that heat generated by the small engine?
One of the ideas I was floating (and continue to...), was using a DC generator to maintain the chassis battery bank, and separately run as much of the interior as possible (using 24-volt devices as much as possible) on a second alternator/battery bank. A 110-volt AC inverter only runs the microwave and the cook-top. Having a 24-volt coil in a water heater (hydronic heating throught the whole rig - and a heat exchanger to warm the prime-mover's block before starting) - then using a heat exchanger to the water heater to reduce the electrical load of the coil, and an exhaust heat exchanger to grab more heat from the output of the small engine (a marine heat exchanger for this). By having more than one source of energy put into a specific task - it ensures optimal efficiency, and shortest run time. While the engine is running, piping in a second air compressor to the govenor line and T-ing off the output line to the air dryer ensures that any running engine produces air pressure automatically to keep the tanks full using the existing controls/filters (makes for quick getaways...).
There was a busnut on the other BBS who had contacted me about building a controller for this type of task - but admittedly I've been side-tracked with work (so sue me - I work in the Silicon Valley at a technology company).
Basically it would monitor a buch of things and determine the optimal time and durration to run a secondary power plant (SPP) - and maintain the vehicle within a certain margin. There was an air pressure tranducer planned to kick on the SPP if the air was below 30psi while the rig was in-station, a prime-mover water temp sensor planned to help warm up the block before starting (you know how those ol' DDs hate real cold), and a battery monitor to ensure the batteries didn't go below their 25% discharge level (and a load current sensor to ensure the SPP was running when a major load was being run - like a 1500w microwave off an inverter).
A small micro-controller would have the operation characteristics for each system plugged into a table - which would be used to run the engine at the RPM needed to maintain a little head-room over the applied loads. It would also provide a safety system to shutdown the SPP if there was a problem (fire, low oil, low water - danger of using too much fuel from the main tank).
I presume a system like this can also include an air-conditioner compresor to help with cooling/refridgertion. Basically, if you try to consider how you can tie a few systems together it will give you more bang for your fuel buck.
Cheers!
-Tim ;D
P.S. - It's a little more complicated putting in a second alternator - as you need to ensure that they don't interfere with each other's operation. A simple pair of relays to "lock-out" the voltage regulator/field on the oposite alternator should be enough to protect the electrical system and components. This can be accomplished by using a pair of double-pole double-throw relays - and wiring the positive supply of the coil of the oposite relay to one of the poles (on the Normally Closed side) and the ignition sense of the local voltage regulator to the other pole in the Normally Open side). So when the first power plant is turned on, it energizes the local relay's coil which breaks the connection to the other power plant's relay coil - while attaching the ignition sense on the local v-reg to the supply (turning it on, and operating the local alternator). Even if the other power plant is turned on - the other relay can't be energized because the coil has no supply power (circuit broken by the first relay) - thus the other v-reg/alternator will not be activated. But - when the first one is switched off - the first relay opens reconnecting the other coil's supply, allowing the second power plant's relay to now be energized, and thus turning on the second v-reg/alternator (and of course locking out the first one).
This way - the first alternator will always be activated - and the second will not interfere with the first's operation. It's a simple bi-stable break before make lock-out safety system.
Alternatively, you could use a Normally Closed single-pole single-throw relay to simply lock-out the secondary alternator (by breaking the v-reg's ignition sense line) when the prime-mover is running (simpler).
Oh and in either case, if you have more than one alternator per power plant (say one for a house bank, and one for a chassis bank), you don't need larger relays with more poles - you simply split off the ingnition sense from the respective relays. -Tim (confusing enough? ???)
Well, actually the old auto generators produced AC, all generators do. The reason it came out DC was that only part of the output was used. One half the alternating current was clipped off by using only a few of the armature segments and what came out was sort of a pulsating DC but good enough for auto use. Then it was pulsed by ignition points so the coil (which is a transformer) could raise voltage high enough to fire the spark plugs!!
Alternators produce AC (!!) but are rectified by diodes to make DC. Again, only part of the output is used.
Kind of sounds like what started this thread in the first place.
Hey CR,
The only reason my Homemade DC Generator is loud is because it is on display, without any shielding, or sound control. ;D
YOU CAN DO IT.
I feel the bigest efficiency comes from the direct drive of the air conditioning compressor, recapture of the exhaust gases, and cooling system recapture of thermal energy. You can make DC with less fuel used(low idle), you can store DC not AC.
I am going to try to recapture the heat generated by the alternator and use it.
Lets take the mechanical engine output, figure loses in conversion to AC 120, or 240. Now take the losses of conversion of the electric motor that drives the electric - mechanical, compressor.
Direct drive belts take 2-4 % , much better than -40, -40 mechanical to electric - electric to mechanical compressor.
I could not cite the proper text book losses, but have found more comfort for less $ and foreign oil used.
OW, sorry I did not mean to hijack your thread. Just add to it.
I would use a 24 volt system if my bus was 24 volt.
Yea I like the vrod approach. I thought a Harley engine would draw some attention. Liquid cooled is a must. Easier to recapture the thermal energy also.
With the 5, or 6 speed trans you could easily choose the ratio to efficiently drive air conditioning, electrical generation, and an air compressor.
I would be willing to help.
Bill
Quote from: Homegrowndiesel on January 27, 2007, 08:06:19 PM
Hey CR,
The only reason my Homemade DC Generator is loud is because it is on display, without any shielding, or sound control. ;D
YOU CAN DO IT.
Yea I like the vrod approach. I thought a Harley engine would draw some attention. Liquid cooled is a must. Easier to recapture the thermal energy also.
With the 5, or 6 speed trans you could easily choose the ratio to efficiently drive air conditioning, electrical generation, and an air compressor.
I would be willing to help.
Bill
It may take a while to find an affordable V-Rod engine and transmission as they are still too new not a lot of salvage. but I will find one and build this. It will be fun, cool, different and a great conversation piece. And when I find all the HD components I will call on you for your offered help. I keep watching E-Bay and Crashed toys .com and will put a bug in my friends ear that owns the HD dealership
As per my earlier post on this thread, I very much like the idea of a simple 12v / 24v DC generator for use as a supplementary battery charger; personally it would only be for use as an emergency back-up as I already have a full-size silent generator for 240v mains voltage (and also, as it happens 12v DC, but only at 8 amps).
I've been looking through the catalogue of my usual supplier of workshop machinery, and I see that 4-5hp Honda petrol engines are far cheaper than I would have expected, and they are ready-to-go with pull-start, fuel tank, varous drive pulleys etc. I realise these will be noisy and shakey little things, but for my application (ie. emergency use) they would be ideal. Carrying petrol isn't really a problem for me as my full-size generator is petrol (yes, I would have preferred a diesel genny, but petrol option was much smaller, quieter, lighter and cheaper for the same output).
As well as various low and high voltage alternators, the same catalogue also includes lots of other devices that the engines can be bolted to, such as air compressors and various types of water pump, including jet-washer pumps - it's a shame I cannot really think of a good use for any of those things on the bus.
I still think my earlier idea of using the back-up engine to somehow drive the OEM bus alternator would be the perfect solution, but I also like the idea of using two small and cheap 12v car alternators rather than a heavy and (probably) expensive 24v one. My house batteries are 12v, so there would be benefits there too.
I couldn't help but wonder why I hadn't come across petrol-powered battery chargers / DC generrators before, given that they seem such good idea. I did a quick search on Google, and the first result that came back was of this unit from Australia:
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fwww.fridge-and-solar.net%2Fgenset%2FGen%25202.jpg&hash=5c70c05a2a89eb6f71e15b17036f9749e0d885bc)
In order to choose an engine to power such a generator / charger I would be very grateful if someone could offer a clear explaination of how to calculate the engine horsepower required to turn an alternator (or alternators) of a given output. Presumably, if the efficiency of the alternator is known it should simply be a matter of converting mechanical power to electrical power? Also, what is the optimum rpm for a car-type alternator? I've always assumed their power output was very flat over a wide range of engine rpms, but presumably there is a speed they are typically most efficient at. I can work our the gearing required between the engine and alternator myself.
Lastly, I very much like the idea of the engine throttle being automatically opened and closed as the load on the alternator varies - in fact my full-size generator has this feature and it is a major benefit. Can anyone think of a simple way to acheive this? Designing custom circuitary to operate servos or stepper motors is beyond me.
Jeremy
Shoot - I just spent 30 minutes writing up a big long explanation of how this is done, and then pushed some funky keyboard combination and lost the whole post by going "Back" (GGGGRRRRRRR >:().
Oh well (the milk is spilled) - I'll try a truncated version. You'll want to have these four equations handy:
Watts = Volts X Amps
Drive Ratio = Alternator RPM/Engine RPM
1KW (1,000 Watts) = 1.34102209 HP
Horsepower = Torque x RPM / 5252
There is also a rule of thumb you'll want to remember: Assume a 20-25% loss at every conversion. This would be mechanical-to-electrical like in an alternator – and even mechanical to mechanical like in a belt drive (some belt drives can be up to 98% efficient, but if they are not maintained can drop to 92% or less efficient – in my opinion I'd play this one safe).
You'll want to start at the alternator as it's the last conversion (I'm disregarding wire "line" loss for this discussion as it should be part of the system design equations already :) ). Make sure the alternator you pick is sized for the system and charge-rate of your system.
For this example – I'll assume we're using a 24Volt (28 volt charging voltage) 200Amp alternator which is belt driven. Also – I'll assume that the max current is achieved at 6000RPM (this information would be in the alternator's spec-sheet). This means that the alternator will create 28Volts x 200Amps = 5.6KW at the output posts. However this is a result of a mechanical input shaft to electrical field conversion. Which means – you'll be drawing 5.6KW x 120% (added 20% of loss to the output power – or a decimal value of 1.2) = 6.72KW at the pulley. If you don't have an engine that'll put out the required HP at 6000 RPM ( or you don't like the "sound" {punn} of an engine running at 6K RPM for any length of time) – then you'll need to use a step-up drive system (belts are typical). So let's add another "loss" to the system: 6.72KW x 1.2 = 8.064KW. This number will let you do two things: 1) pick an appropriate peak output engine, and 2) a suitable drive system.
To pick the engine, convert the KW to HP (KW x 1.34102209 = HP) so: 8.064KW x 1.34102209 = 10.814HP. You'll need to pick the next size UP from this or you'll stall out the engine at max load. Let's say that we have selected an 11HP engine.
To pick the drive system – you need to figure out the max power and RPM of the engine from the published performance table. Now figure out the pulley size by measuring the alternator pulley size and getting the circumference (let's say the alternator has a 2" diameter pulley). The circumference of our alternator pulley is thus: Pi x Diameter = Circumference or Pi x 2" = 6.283" circumference. Now figure out your required drive ratio by finding the RPM at which your engine creates just a bit more than the peak power required (we'll say 11HP in this case – and for this example say that the hypothetical engine's performace table indicates that this occurs at 2600RPM). So your peak output of the alternator (28Volts@200Amps) occurs at 6000RPM on the alternator and the 11HP is generated at 2600RPM. So find your drive ratio by 6000 / 2600 = 2.308:1 (or 2.308 rotations of the alternator for every 1 rotation of the engine). To find the size of your engine (drive) pulley – take your drive ratio number (2.308) and multiply it by the alternator pulley circumference (6.283"): 2.308 x 6.283" = 14.501" engine pulley circumference. You can get your pulley diameter now by reversing the math: 14.501" / Pi = 4.616" diameter. You'll also need to ensure that your drive system can support the power rating for the length of time it's being used (i.e. 11HP under continuous use). Some systems will require the use of a dual slot pulley (or worse if really big). You also need to ensure your engine can support the side-load of the tension of the pulley/belts against the crankshaft bearings (or the engine will fail pre-maturely). You may need to use a short shaft and a set of pillow blocks (aka bearing blocks) to take up the belt load from the engine. Just be sure to align your pulleys so they don't eat belts quickly.
Both your selected engine and selected alternator should come with performance tables showing (for the engine) how many HP are generated at a certain RPM – and (for the alternator) how many Amps are generated (at the charging voltage) per input RPM. You'll need to match up values of the alternator to the values of the engine. This is easily done within a look-up table in a microprocessor (and you'll probably need one to controll this well - as most of-the shelf voltage regulators are not suitable for this task). You'll also need to get the table for the field current of the alternator to the output amps. Again – plugging these into a microprocessor's look-up table is easy. A voltage sensor can tell the microprocessor if the voltage is below the nominal rating (less than 28V because of draw-down) and increase the RPMs of the engine. A smart-desiner's voltage regulator can also prevent the field from getting a bunch of current until the engine is at an RPM where it can support the requested current (a fractional multiplier equation [to derive a "margin"] will ensure that the engine power [throttle] is always that fraction above the actual requested alternator load - and then only allowing the requested output to be so-output in relation to the >>actual<< engine RPM via the look-up table will prevent a stall).
By adjusting the multiplier (engine HP to Alternator output "margin") you can affect the rate at which the engine will obtain it's desired RPMs. If you want to get more complicated - you can vary the magnitude of the multiplier over the base value (with another multiplier) by evaluating the difference of the requested current in relation to the actual output current. This way it will push the engine up faster if a large load is detected - but will only rev up the engine slowly under light loads (rate of acceleration affects fuel economy - and if it's a light load, it's more likely it won't negatively affect the battery pack's charge state with a huge draw). This would probably be optimal, as allowing the batteries to take care of long term variations in smaller amplitudes will stabilize the system faster.
This system can be further improved with load current sensors (current loops or a shunt) to tell the microprocessor exactly how much power is being drawn from the alternator (and even another to show the ammount and direction of charge/discharge from the battery) – which will give it a better picture of the power situation in-circuit. For example – say you turned off your 2400Watt inverter and now there is no draw on the alternator other than the trickle the batteries need – the shunt will note this change quickly and the voltage regulator can drastically cut the field current to the alternator to prevent a voltage spike, keeping only the trickle charge to the batteries. Also battery and ambient temperature sensors can be used to better match charging rates to the current battery states (and with a microprocessor controlling the alternator - you can do those fancy multi-stage charging steps).
If you have the microprocessor running the engine and watching the system voltage/current already - you may as well put in some other features like engine warm-up before loading, engine cool-down before shut-down (required for turbo longevity if one is used on your engine), low-oil shut-down, over-temp shut-down, low-fuel shut-down (if the generator and Prime-mover are run from the same tank), auto-start, auto battery-maintain, "quiet time" (hook up a clock and set an "out of bounds" time-frame when most in your camp ground are sleeping...), battery fan controls, etc.
Of course building your own voltage regulator is a bit complicated, and making a mistake, and/or not having hard fail-safes (fuses, voltage limiters, diodes, etc.) can destroy very expensive parts in short order (say a $3000 inverter? or a large battery bank?).
It's not for the faint of heart – but it can still be done with a good deal of planning.
Heck – diesel locomotives use a similar control system to regulate the speed of the engine/generators – and Honda has produced small A/C inverter-generators that do this all the time (so it has been done, and can be done again).
Do it your way – and be safe (put in emergency shut-downs and fire/smoke detectors), there's nothing worse than burning down your bus with your family in it... :'(
Oh - almost forgot. If you use a current shunt on the output, it creates a voltge across it. If you tap in a low-voltage solenoid/actuator to the measurement lugs of the shunt - the voltage could theoretically push the solenoid out harder/farther with a higher load. Attaching the output shaft of the solenoid to the throttle is the easiest way I can think to automatically control the speed of the engine based on the load - but this would have to be coupled with an anti-lug govenor (which I think most small engines have in them anyway). Sounds complicated and hard to ballance - mostly because is is :). Manufacturers who use this method have custom actuators and throttle springs for this function.
Another concept that I've not seen but is concievable - is to drive and actuator from the voltage regulator's field output (more field current - equals more alternator load, and should be matched with more throttle movement) - this could possibly stabilize a generation system faster (but don't quote me on this :-*).
Cheers!
-Tim
P.S. Hope this wasn't too long-winded and boring... :)
^^^^^^^ ;D ^^^^^^ That's what I'm talking about.^^^^^^^ ;D^^^^^^^
THE ABOVE POST BY TIM STROMMEN IS AN INFORMATIVE, INTELLIGENT AND WELL ARTICULATED SCHOLARLY POSTING.
You sir, have placed in a "nutshell" the most important "basic" factors to consider needed to plan such an interesting project (though not for the faint of heart) without the "confusing micro-details" that would have earned me a PhD in a few more weeks. The exact calculations and formulas that you presented to derive at correct equipment combinations is the first in this board, bar none.
TIM STROMMEN, You are an asset to this community. The substance of your post exceeded all expectations in this thread. I salute you!
Hey Gr8njt,
Thanks for the note :o, it was rather entertaining to read (and all this after the thread almost got away from Captain Ron).
The accidentally deleted post I wrote previously may have given you the extra edge to get that PhD ;).
Cheers!
-Tim
I think its a conspiracy started by Generac ;D
Quote from: Tim Strommen on January 30, 2007, 03:56:02 PM
Hey Gr8njt,
Thanks for the note :o, it was rather entertaining to read (and all this after the thread almost got away from Captain Ron).
The accidentally deleted post I wrote previously may have given you the extra edge to get that PhD ;).
Cheers!-Tim
Tim,
You deserve the accolade for a great basic instructional post void of discouraging statement.
I bet Capt Ron and a lot of Busnuts (me included) really appreciate posts like yours that has real substance to help us in these taboo projects so we don't have to do projects like this behind closed doors. Check your PM.
Thanks again.
Already replied to your PM via email. I believe the only reason I'll discourage anyone is to promote safety only.
Otherwise, I try to obviously call out my opinions and just stick with facts the rest of the time (of course - even I make mistakes when I'm tired, but I'm quick to admit them when it's called out :)).
Git-er Done!
Cheers!
-Tim
Tim, I also would like to thank you for a very well written post, or as gr8njt put it, INFORMATIVE, INTELLIGENT AND WELL ARTICULATED SCHOLARLY POSTING. I Just reviewed all your prior posts and they all fit into the same category so I am happy to have such an articulate member here on the board.
It would be very interesting to me, and I believe to many others, to find out what your background is that gives you this capability of posting such responsive replies. It would also be interesting to find out if you also have practical experience in developing such systems.
Thanks again,
Richard
Ok you two enough a$$ kissing ;D Thanks Tim ;) Of course I didn't under stand any of it but when it comes time to build mine you will be the first person I'll have my helper Bill call when we get stuck.
I used all the formula provided by Tim and played with calculations going forward, backwards and every which way with every possible combination of parts for the past 48 hours that I feel I could now do it in my sleep. Factoring any projected energy consumption, they always arrive at a logical and safe combination to putting the needed parts together. It eliminates the incompatible part/s and redirects to the correct specs of any needed part. Now I know what other parts I will need to "hunt" for, purchase and/or fabricate.
With the aid of these tools (formula), they reinforce confidence that you're on the right track and keeps the project well grounded (no pun intended) without the irrelevant bull crap.
Quote from: DrivingMissLazy on January 30, 2007, 07:40:00 PM...It would be very interesting to me, and I believe to many others, to find out what your background is that gives you this capability of posting such responsive replies. It would also be interesting to find out if you also have practical experience in developing such systems...
I'm a Senior Test Engineer at a video processing technology company in the Silicon Valley (Anchor Bay - we make the DVDO brand video scalers). Previously, I installed commercial telecommunications infrastructure in the same area, and previously desktop support for a law firm out in Palo Alto (Wilson Sonsini Goodrich & Rosati - WSGR). Before that I installed Home Theaters, and before that car stereos (competition and show pieces). My night job(s) were running sound at a few clubs, and a small recording studio in Emeryville - and eventually front-house sound for a local S.F. Bay Area band "The Ones and Zeros" for about 3 years in the beginning of their carreer (they are still around - and they gave me the nickname "10-inch-Tim", don't ask... ;D).
I also had a breif stint as a Loss Prevention Officer for Fry's Electronics (big "Best Buy" competitor) during the "dot-com burst". I've been around the block a time or two.
I've done over 300 car stereo installations over the last 10 years (a few recently), and have have some experience restoring cars ('73 vintage and older). For home theaters, I've done low and high-voltage electrical for audio and video distribution, climate control, and lighting control in over another 100 installs (including a few jobs that were over $500K).
I've designed a few stand alone power systems for a few cabins (renewable/non-renewable off grid power), and desinged several PCBs for requested tasks (for friends-colleges).
I just generally enjoy electronics and engineering. All this, and I'm only turning 27 in a few days ;).
My bus is just another outlet for my restless mind (and while it's too cold/wet to work on that I lurk around here and BNO's bbs).
That's me...
Cheers!
-Tim
P.S. From my install days (both Home Theater and Car Audio) I can make one more recommendation: design three electrical systems. The first is to be designed based on what you'll only need as the bare minimum to sustain your intended use pattern. The second should include the maximum "luxury" you would dare dream to cram into a bus (or car or home). The final should be a happy medium (leaning towards the maximum you can afford), between what you've designed in the first two. Things will change later, so make things easy to chage (and add a little margin). Don't make one system heavily reliant on any other system - this will require more work if you make a change later (my old boss for commercial telecom gave me a good nugget for this one: "If you have to do it twice, you didn't do it right the first time - and you won't be making any money on it") -Tim
Thanks so much Tim. It is always so interesting to me to see where others have BTDT. Quite an interesting life so far and I suspect it will get even more interesting as time goes on.
Richard