Author Topic: Small slow speed alternator  (Read 6131 times)

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Offline Rustkolector

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Small slow speed alternator
« on: May 06, 2014, 12:40:54 pm »
Hi,
I am new here. I am working on a small alternator project that does not involve wind or alternative power use, so please excuse my intrusion. I am currently stumped at the moment, but I know the expertise can probably be found on this site. I want to build a small PM alternator for operation in the 350-500 RPM range to produce a usable 12v output, but 6v may be an alternative output. The stator outside diameter cannot be over 4". The output needed is approximately 25-30 watts. The output would be rectified to DC, controlled with an voltage regulator, and used for resistive lighting. I have considered a small Denso industrial engine 3 phase alternator stator, but I don't think these stators use more stator coil wire turns to produce the higher voltage. As you can guess, I am trying to avoid rewinding any potential use stator, if at all possible. Any suggestions on potential stators, or any other suggestions would be greatly appreciated.

Jeff

Offline rossw

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Re: Small slow speed alternator
« Reply #1 on: May 07, 2014, 01:42:46 am »
I've seen some quite small servo motors that would likely fit within your 4" (100mm) diameter requirement.
Many of these (even quite small ones) are capable of several hundred watts at a decent speed (2000 RPM), so at your 500 RPM would very likely make enough for your needs.

Most have precision stator/rotor combinations, great bearings and 3-phase output.

I was looking on ebay for you as an example, and found a broken one (cables broken, some other scuffing on the casing) going out silly cheap. Might be a good option.

Offline Rustkolector

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Re: Small slow speed alternator
« Reply #2 on: May 07, 2014, 10:28:17 am »
Rossw,
Would you happen to have the link to the ebay auction you mentioned?

Jeff

Offline rossw

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Re: Small slow speed alternator
« Reply #3 on: May 07, 2014, 04:33:07 pm »
Rossw,
Would you happen to have the link to the ebay auction you mentioned?

Can't see the one I found yesterday, but this is similar. They don't give the chassis dimensions, but I'm sure you can google the part number and find it fairly quickly. This seller seems to have multiple units on offer too.


Ebay item 290843151989

Offline Rustkolector

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Re: Small slow speed alternator
« Reply #4 on: May 08, 2014, 09:44:54 pm »
Rossw,
Thanks but that one is rated at 8000 RPM and I don't think it would produce much at 400 RPM. For my use a short stator is preferred and I think the automotive alternator type stator would be best for my use. It looks like I will have to figure out how to rewind one of the small diameter automotive 12 pole stators for 12v output if I want slow speed.

Jeff

Offline Norm

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Re: Small slow speed alternator
« Reply #5 on: May 09, 2014, 09:47:20 am »
check on Windstuffnow...he experimented with car alternators awhile back .
Norm .

Offline rossw

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Re: Small slow speed alternator
« Reply #6 on: May 09, 2014, 04:44:02 pm »
Rossw,
Thanks but that one is rated at 8000 RPM and I don't think it would produce much at 400 RPM.

I couldn't find the one I'd originally seen - perhaps it sold. I'm sure it was only 3000 RPM, which should have produced a non-trivial output at 400-500. They are very well made though, "precision" devices vs the banged-together junk they stick in cars. That said, there isn't any one "right" way to do it - look around, keep your mind and your eyes open, I'm sure you will find something suitable (or adaptable).