I am working on a project for the RC flying club I belong to. We have moved to a new flying field that has no grid power so I am building a a power source. It will consist of an engine driven alternator, and a solar panel to charge 2 6v golf cart batteries in series. It will have 12v and 120 volt outlets. Folks can plug their 12v battery chargers into banana jacks or use 120VAC power from a 1500w inverter. The first phase is the engine driven alternator. I picked up a 99cc, 4 stroke OHV engine from Harbor Freight for $79.00. They claim about 3HP. I then got a 10SI from the auto parts store, $29.00 + $15.00 core charge. I first made some adapter plates to be able to mount the alt in a direct drive setup.
Next I got the coupler pieces and modified the one to fit on the 10SI. I bored the coupler so I could install the nut and secure the coupler to the alt shaft.
Now to bolt it all together!! So far things have gone pretty smooth.
Nice work! Curious to see how many amps you get...
Here is the curve for the 10SI. Looks like I should get about 48 Amps at 3600 RPM and 23 Amps at 1600 RPM. 48 x 14.5V = 580 watts. At 50% efficiency thats 1160w input needed. 2HP per KW = 2.32 HP. So if my math is correct, the little engine should spin the alt with no problems. Hopefully I can get it finished this week and do some testing.
Bob
squarebob,
That's a great little project !
Simple and clean. Should prove to be very reliable.
Rebuild kits for the 10Si are very inexpensive.
Bearings, brushes, and diodes for $20 !
If you every want to step up, I think the 12Si should bolt right in place.
Gives 94 amps and has heavier windings.
nice job,
veggie
You should be able to do 48A on 3HP just fine... Cool build. What do you fly?
Quote from: squarebob on February 05, 2012, 03:34:09 PM
I then got a 10SI from the auto parts store, $29.00 + $15.00 core charge.
Bob, can you elaborate on this? Where did you get the 10SI for $29 + $15 core?
Thanks
Ron
Ronmar, I fly mostly AMA and SPA precision aerobatic pattern planes. This one pictured is powered by a .91 Cu. In. 4 stroke running 30% nitro fuel.
Bob
Autozone or Advance Auto has the 10SI for $29.99
part # 7127
I ask for 78 Camaro 350 with air to get them to find it.
http://www.autozone.com/autozone/parts/Alternator/_/N-93xme?filterByKeyWord=7127&fromString=search&isSearchByPartNumber=true
Here is some good info on the 10 and 12 SI
http://www.madelectrical.com/electricaltech/delcoremy.shtml
Quote from: squarebob on February 06, 2012, 03:52:54 PM
Ronmar, I fly mostly AMA and SPA precision aerobatic pattern planes. This one pictured is powered by a .91 Cu. In. 4 stroke running 30% nitro fuel.
Bob
From that picture and what we know, it appears that you are outstanding in your field! :D
Great project, SquareBob. Nice plane, too. Thanks for the link to madelectric, that was a good source of info. I last flew a Goldberg Extra 300 on and oversized nitro burner and some electrics including a glider. Flying at 5600 feet cut the power enough that my 300's knife edge loop was more of a "floop". RC flying is a ball, I miss flying with the guys at the Taylor AZ airport Wed. mornings. That was one sweet deal for the RC'ers!
Best Wishes,
Bruce M
Thats great info Bob, thanks. There are so many vehicles it was used in, and they charge a different price for each of them, so having the vehicle that used the inexpensive one is the trick:) If it it was a Camaro, I am guessing it probably has a 3.25 OD pulley? The specs for that pully shows about a 5/8" groove depth so the pully ID is probably around 2" Running belted off a 24" 6/1 flywheel at 650 RPM, it should spin right around 8000 RPM which is the peak output RPM... Hmmm:)
Nice plane. Havn't flown fixed wing in quite a while(been a rotorhead for a few decades now:)) But some guys I work with have sucked me into flying indoors, and the cool small electric fixed wings are looking like a lot of fun to me...
What are you going to do to keep the noise down on your power plant?
rcavictim, I have been outstanding in a bunch of fields!!!!
ronmar, the pulley that came with it is 2.6" dia.
Did your engine come with that mounting bracket bolted to the bottom of the block? I got the 79cc version of this same engine before they discontinued it. It only has blind holes in the bottom of the block for mounting, I need a bracket like that...
Bio, the stamped mounting plate came with the engine.
Bob
If anyone is looking for different size alternator pulleys, Here is a good source:
http://www.ase-supply.com/category_s/183.htm?searching=Y&sort=1&cat=183&show=100&page=1
Quote from: squarebob on February 05, 2012, 03:38:16 PM
Next I got the coupler pieces and modified the one to fit on the 10SI. I bored the coupler so I could install the nut and secure the coupler to the alt shaft.
I really like how you bored the coupler here to install the nut. I'd like to do something similar but without a lathe, that's not going to happen. Could the set screw be used to hold the coupler in place without the nut or maybe cut a slot in the alternator shaft for a keyway?
You need to use the nut to secure the fan and coupler/pulley to the shaft. I would be willing to bore a coupler out for you.
Bob
In doing some research, I found out I can add a diode to the #2 terminal on the 10si and increase the output voltage by about .6 volts. I tried this on my 6/1 setup that charges the starting battery and lo and behold the charge voltage went from 14.7 to 15.2. I put a second diode in series and got the voltage up to 15.6. I am going to wire this all up permanent and put a switch on the second diode so I can take it in and out of the circuit. This way I can "equalize" the battery by throwing a switch that adds the second diode into the circuit to get the higher voltage.
I found the info here on page 52
http://www.ankan.nl/download/12%20Volt%20Doctor%20Alternator%20Handbook.pdf
I will also incorporate this mod on the project that this thread is all about.
It is funny that little things like this get us excited. :D
Bob
That's an excellent reference for alternators, Bob. Wish I'd had it on hand years ago.
It's very handy that your 10SI's regulator has the extra terminal for the incoming voltage to the regulator. Some don't have that. A Schottky diode (rated at 20V or better) would allow for a smaller raise in voltage, if needed, since it has about half the forward voltage drop. On page 36 figure 61 you can see how lowering the input voltage by the diode's forward voltage drop will cause an increase in regulated voltage.
I hope Biohazard will find this.
Best Wishes,
Bruce
Quote from: BruceM on February 19, 2012, 10:03:46 PM
I hope Biohazard will find this.
Watching intently, definately good info. ;D Bob's been nice enough to make me a coupler so I can build the same.
Looks like we're saving about a thousand bucks to DIY... :o
http://www.alten-dc.com/products/item/149-12-volt-55-amp-gas-powered-battery-charger.html
And that little sucker runs at 7000 RPM. :o
I have been busy making a box for everything to fit into.
More pics. I even found time to add a flywheel and starter to the petter. I am getting too old to be pullin' on a rope to start a diesel!!
Hi Fellas. A bit late but earlier there was interest in a cheap external regulator. A few years ago I used an Email alternator off a 1970 chrysler valiant 245 on an early sports car to replace the dozy generator. The regulator was toast but I managed to pick up an aftermarket electronic replacement which as well as being rediculously cheap also enabled the alternator to poke out around 15 volts at full output. The car had beautiful headlamps as a result and the high voltage didn't damage the battery or any other components. Hope this is of some use. Cheers, derb.
Quote from: squarebob on February 20, 2012, 02:02:53 PM
More pics. I even found time to add a flywheel and starter to the petter. I am getting too old to be pullin' on a rope to start a diesel!!
Bob,
Nice looking starter install. I caution that you may need to extend the chassis rail(s) under the starter and add a rear bracket to the starter to keep it from vibrating in a self destructive manner from engine vibration. Looks like a mechanically pumped pendulum to me the way it is bolted on presently.
Quote from: squarebob on February 19, 2012, 05:23:51 PM
In doing some research, I found out I can add a diode to the #2 terminal on the 10si and increase the output voltage by about .6 volts.
I wonder if there is a limit to how many volts you can get? Could you trick it into giving you 24v with enough diodes?
My understanding is that the main rectifier diodes in the alternator are "avalanche" diodes, which means that they have a limited reverse voltage capability. This is a design safety feature, so that if the regulator goes nuts (max output), the diodes will limit the output voltage to avoid damage to the rest of the automobile's electrical system. In a worse case scenario, it should only burn up the alternator, not blow up the battery, engine computer, radio, etc. You can get a little extra voltage, but I don't think you can go up to 24V. You can get replacement diodes designed for a 24 or 48 volt system - but you probably should have bought a 24 volt alternator to begin with.
Instead of using one or more diodes to fool the regulator into giving you higher voltage, you can use a zener diode to provide whatever voltage drop you want, they come in a wide range of voltages.
Yep, that works, by lying to the regulator. with the sense line seeing less voltage it ups the output to compensate for the voltage lost across the diode. You should be able to do 24V, but the issue is usually that the diodes in the rectifyer have trouble switching the higher voltage at higher currents. Bob went over this very well in his white paper on running the leece-neville alts at increased output. You really need better rectifyer diodes.
But diodes in-line with the sense line, if the alternator wiring configuration will allow it, is a poor-mans way to taylor the output charge voltage above the automotive single default voltage
squarebob,
I really like that Petter setup that you built. Very compact.
That's exactly what I have in mind for my little air cooled 165 Changfa and Delco 12Si.
How does the engine react when you switch on the alternator load.
Does it really bog down or just give a puff of black smoke and bark a little ?
veggie
Everyone talks about stalling out their engines with too much load. No need to spin the alt at 5000 rpm if the engine can't handle the load. I sized the pulleys to not overload the engine. The engine puts out 1 HP per 1000 RPM. I slowed down the Alt. RPM based on the performance curve I have for the unit (see attachment). The engine is variable speed so I can run the alternator RPM from about 500 (and 0 output) up to about 2000 RPM. Now the fastest I can get the engine to run with a battery bank that needs a lot of charge is about 3000 RPM and 1725 RPM on the Alt. It puts out about 35 Amps at 28 volts and a little gray smoke from the exhaust. As the bank charges up and the Amps drop, I can slow the engine down to match the needed output and save fuel. I built this as a charger to take my bank from about 80% to 100% and as a backup to my GM90 setup.
Bob
Nicely done !
veggie
Quote from: squarebob on February 06, 2012, 05:46:53 PM
I have been out standing in a bunch of fields!!!!
That's perfect, I'll have to remember that!
Great project. I've been wanting to do something similar, so this is all very interesting to me.
Well the direct drive worked good during the testing phase but I did not have a set of GC batteries to really put a load on the system
When I hooked up a REAL battery that needed some charge, the little engine just struggled too much with the load. So I changed it from direct drive to pulleys. I went with a 3" on the engine and a 4" on the Alt. So now the Alt is turning at 75% of the engine RPM. Well that really made the little engine happy. It is not overloaded, I can run the RPM down and it runs fine. I am able to pull 50 AMPS at full throttle and I think that is pretty good for this setup. Remember, it's just a 99cc Harbor Freight engine! Now I need to finish up the wiring and the gauges and such so I can get the system online at the flying field.
squarebob,
That's a great looking unit. You did a nice job there !
Where did you acquire the vibration isolators ?
(part number?)
cheers,
veggie
cheap cheap cheap
ANCHOR Part # 2393 Trans Mount
Rock Auto - $3.68 each
Fleabay - $3.17
Other places also
Bob
Great work, just like before. :) I guess my little 79cc HF engine won't have the balls to direct drive either. :-\ I think I'll try a bigger engine with the direct drive setup....
I'd like to see a bracket off the outside bottom bolt back to the mounting plate. Looks like there will be a lot of twisting force on that standoff.
SquareBob - how long are the bolts (threads) coming out of those rubber isolators (trans mounts)?
Tom, Thanks for your concern. The bottom standoff is 1" diameter round stock with a 5/16" hole drilled through for the 5/16" bolt. It is solid as a rock.
Ryan, the bolt coming out of the mount is just shy of an inch long.
Bob
Great job on the nice looking charger, SquareBob, at an amazingly low cost. I hope all the other RC'ers in your club will appreciate your effort greatly.
Happy Landings,
Bruce
Project Update: The system is completed and installed. I added a 85W solar panel and made a tracking mount for it also. The project is a success and the club is enjoying the system a lot.
Quote from: squarebob on February 26, 2012, 07:47:08 PM
I slowed down the Alt. RPM based on the performance curve I have for the unit (see attachment). The engine is variable speed so I can run the alternator RPM from about 500 (and 0 output) up to about 2000 RPM.
A lot of folks caution against running the alternator too slow due to decreased fan speed/cooling air flow.
How hot does your alternator get under load when spinning so slow?
The unit doesn't seem to get hot as the batteries charge up pretty quick. It might pull 40 amps for a few minutes and then start ramping down to 15 amps in 15 minutes run time. We then shut the unit off and let the solar panel do the rest. The solar panel does a great job keeping the batteries topped off and really do most of the charging. The system has only consumed about 1.5 gallons of RUG in the 9 months it has been in service. Only on real busy flying weekends does the unit even get started.
Bob