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Aug 07, 2008, 12:27 AM
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Discussion

How to Convert an Alternator to A Motor


http://www.alternatorconversions.com/

It cant be that hard to do and I am sure that there are more then a few guys on here that have a good idea about what needs to be done. Can any one give me any advise. Is there any way to get a idea of final out put power?

thanks Mike
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Aug 07, 2008, 02:32 AM
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I have tried it once because I thought i could brake verry effiecient with it
but I dont think It will work. staror coil exist of one or two windings only and are overlapping a lot ..... rotor is an axial coil ... when I powered one phase I could not feel anny cogging when turning the shaft by hand ... maybe I`m just stupid ...

than also there are still brushes ...
Aug 07, 2008, 11:28 AM
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Yea ther are still brushes. My line of thought and it may be way off but you would have to power the brushes up some way. That would energize the center coils to magnatize them. It wight be as simple as a constant voltage and constant amp suply or you might need to run a brushed esc on that part and a brushless esc on the out coil's witch are 3 fase dc. I dont know but it is worth a try.

Mike

Ps my spell check is not working.
Aug 07, 2008, 11:41 AM
Registered User
you can order permanent magnet rotors that slip right in...then you would probably have to bypass the rectifying diode connected to the stator and connect straight to the wires on the stator via an ESC....search for permanent magnet alternators to find the parts.
Aug 07, 2008, 11:43 AM
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Good tip. I didnt think about that. I figured bypasing the rectiye was going to be need. once it is removed it leavs you with 3 wires. I dont know if it would be as simple as conecting a esc to those wires but I dought it.

Mike
Aug 07, 2008, 03:00 PM
Engineer for Christ
IBCrazy's Avatar
Get an alternator from an old motorcycle at a salvage yard. Many Yamaha's and a few Honda's have outrunner style alternators that can be hooked up directly to and esc and run as a motor.

Some models I believe have an outrunner style alternator:
Honda: CX500, CX650, GL650, GL500, V30 Magna/Sabre
Aug 07, 2008, 04:18 PM
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That is pretty cool info and Might very well come in handy down the road. But for this project I am needing a bit more power. I was looking to do this on as big of a alternator as I could find in the local wreacking yard.

Mike
Aug 07, 2008, 07:21 PM
Registered User
It is very easy to convert an alternator to a motor, remove the diodes and regulator and it's a motor. Buy a cheap 80 amp Mystery ESC off Ebay and it will run at a low RPM. Alternators have a KV in the 100 to 200 range. To get full power it may require an ESC rated at 200 to 300 volts and 100 to 200 amp.

With a KV of 100, a 200 volt ESC will give about 15,000 RPM which is well within the operating range of an alternator. Just about any newer alternator would be rated at 100 amps or more.
The area of the stator times 2 N/cm*cm gives about 20 HP for many alternators.
Aug 07, 2008, 07:40 PM
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well I just came to post and found that you beat me to it. I did some test putting 12v to the arm. and using a dvom and I was pretty sure it would work great. I do have a question what do you do with your armature. Did you supply power to it if so what and how.


It my not be but that is what this looks like http://www.robotmarketplace.com/prod...ETEKBL250.html
I bet that seeing as size don't matter you could build a speed controler fiarly cheap. $200 or less. here are some speed controllers for 72v 450amp
http://www.electricmotorsport.com/st...rs_alltrax.php
Mike
Last edited by cars4fun2001; Aug 07, 2008 at 10:30 PM.
Aug 07, 2008, 09:25 PM
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It works


Ok did some testing and it worked. The amp draw on a 3s pack to the armature is <>5.5 amps. I had one 3s pack feading the armature direct and one fedding the outer windings through a 70 amp cermark esc. KV is extremely low which is great for me.amp draw trough the esc is .5 amps wot when I put my hand on the pull and try and stop it from turning the amps go up to <>3.5 and it will not stop. ball park rpm on a 3s pack is around 110-120

I am not a electrical engineer just a common guy with a crazy imitation so I am asking for a little help with figuring out what I have as far as power is concerned.

I have a couple of thoughts about controlling the "altamotor" you could very ether the brushless controler or a brushed controler or both. I have know clue which set up would be better so any input on this would be great.


Mike
Aug 07, 2008, 09:47 PM
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more testing with some very unexpected results. The brushless esc has little to know effect on rpm but I connected a brushed esc into the armature feed and it has great effect on the rpms. I need to do some more testing but it appears that the if the voltage is the same on both it is not good. the armature needs much less voltage. some where around 1/4 throttle resulted in the highest rpms any more or less and they dropped.

Mike
Aug 07, 2008, 10:09 PM
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ok at highest rpm armature amp draw is around .4amps and <> 9 volts. Kv is much higher the I originally thought. That may not be a big deal. Can any one tell me how to go about figuring torque. I know that this is a 140amp 14.4 volt alternator. From reading I have found out that these will put out <>130 volts with out the regulating diodes. Does that mean that when being used as a motor that it could handle 140 volt and 140 amps and be reliable? I would not intend to push it that hard but if that is the case then it would be great for what I want. I would like to see 72 volts with short burst of 130 amps on acceleration hopefully dropping to around 60 amps shortly there after.

Mike
Aug 07, 2008, 10:42 PM
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the more I look at the info on the motor and speed controler here http://www.robotmarketplace.com/prod...ETEKBL250.html the more I am convinced that it is nothing more then a converted Alternator the esc is limited to 48 volts which is a bit less then I want to run. If I can not find a higher rated speed controler I might have to try to make one. boy is that going to be fun.

Mike
Aug 08, 2008, 10:44 AM
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If my line of thinking is corect I could use higher voltag to get teh motor started and then even with a steady sin from a bl controler I could decrease the voltag going to the armatur to increase to speed.

Mike


sorry guys spell check still is not working.
Last edited by cars4fun2001; Aug 08, 2008 at 10:53 AM.
Aug 08, 2008, 12:18 PM
Registered User
maybe you can change the stator wiring around, if its a high amp alt it could be delta wound right now...maybe try rearranging the leads to star? or vice versa...

so you have an esc on both the staor and rotor... or only the rotor?...thats weird.

if you want to measure torque, theres a relatively easy way to measure it...search for science class teaching aids...and youll see how you can make one...its basicly a wheel and two counter weights and a rope if i remember correctly.

or you could probably stick a torque wrench on the pulley nut and see where the needle points when you apply power...but im not sure if torque will be the same at center or around the perimeter of the pulley.


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