Author Topic: Automotive alternator to PM alternator  (Read 19724 times)

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rustkolector

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Re: Automotive alternator to PM alternator
« Reply #54 on: April 21, 2015, 09:47:33 PM »
Opps!!! I hit the wrong key. Sorry. The maximum output at each RPM was determined to be when the input voltage to the regulator dropped to about 13.3v. Test alternator was driven by a variable speed lathe.

RPM    Volts     Amps    Watts
350      12.0      .99         12
400      12.0     1.88        22.5
450      12.0     2.71        32.5
500      12.0     2.93        35.2 (Voltage regulator maxed out at 3A)

Using a higher amp rated voltage converter the max output at 500 RPM is estimated at 50 watts and 60 watts at 550 RPM. This higher output is not needed for this, or future projects as the alternator/generator above is more than adequate as is. The project 1/8th scale engine is basically complete, and shows good power at 450-500 RPM.  The vintage looking generator frame is in progress. Many, many thanks to all who offered advice on this project and a especial thanks to Flux. THANKS GUYS!
Jeff

Bruce S

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Re: Automotive alternator to PM alternator
« Reply #55 on: April 28, 2015, 12:53:45 PM »
That is great to see/read.
Would you happen to have pics of the internal windings ?
We like pictures  :D, also gives others a visual of what wave windings are.

Many Thanks for the update too!
A kind word often goes unsaid BUT never goes unheard

rustkolector

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Re: Automotive alternator to PM alternator
« Reply #56 on: February 15, 2017, 08:52:58 PM »
I started this thread a long time ago and must apologize for not posting the finished project. To remind all here,  I wanted to build a small PM alternator based on an auto type alternator stator that I had. My retirement hobby is building working scale model engines based on old slow speed stationary engines of the early 1900ís. I like my model engines to do what the real engines did during their working career. DC power generation was a very common application. So this project was a 1/8th scale model of a 25hp Bates & Edmonds gas engine DC electric plant which required about 36 watts of electrical output at 500-600 RPM. The B&E engine was a very unusual gas engine in that it used the alligator valve link system operated by eccentrics and pull rods to open the overhead valves. The engine runs on propane.

My problem was 18+ volts at low RPM and cogging. In the end, the 12 pole, 36 slot 93mm dia. stator was rewound for higher voltage using the original wave winding, neo magnets were installed on a new steel rotor using the offset method for cogging reduction, and the AC was rectified and regulated for a smooth 12vdc output. The generator was modeled after an early Garwood DC generator. I am very happy with the final project and thought it might be of some interest to those on this helpful forum.

Thanks again for the help.
Jeff

https://www.youtube.com/watch?v=52cj8px3GSA


« Last Edit: February 15, 2017, 08:59:09 PM by rustkolector »