Author Topic: Pettergens  (Read 10371 times)

fattywagonman

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Pettergens
« on: June 10, 2006, 02:23:38 PM »
 Here's a photo of a Mini petter coupled to a 48 volt PM alternator...


Doug

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Re: Pettergens
« Reply #1 on: June 10, 2006, 06:18:37 PM »
Interesting, and clever use of a GM alternator stator. What are you using for rotor magenets and how close is the fit and radius of the rotor to the stator? Assuming you used rare earth magnets what is the flux density in the air gap and teeth of the stator does this cause any heating problems or iron saturation?

Doug

It looks very slick you deserve a pat on the back!

fattywagonman

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Re: Pettergens
« Reply #2 on: June 11, 2006, 07:50:57 AM »

Doug

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Re: Pettergens
« Reply #3 on: June 11, 2006, 08:35:11 PM »
That's very interesting....

And not very hard for a DIYF to copy. Thats a clever rig you built for th e Petter....

Doug

fattywagonman

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Re: Pettergens
« Reply #4 on: June 12, 2006, 03:33:14 AM »
Hi Doug the output is 1.5 kW @ 1400 RPM... ... It will make up to about 2 kW but the RPM's need tpo get up close to 2K.. the alternator does not get hot at all... 

mobile_bob

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Re: Pettergens
« Reply #5 on: June 12, 2006, 05:25:53 PM »
at what voltage can you get 1.5 kwatt?  what rpm?

i see you post this as a 48 volt machine, i was assuming this to be able to charge a 48 volt bank.
from your voltmeter you are a bit short, unless the thing is loaded at 1.5 kwatt.
if so i am impressed

where do you get your basis for 1.5 kwatt output?

did you rewind the stator for higher voltage?

how long did you run at your reported 1.5 kwatt?

how is the stator cooled at this level of output?

the original delco stator wont hold up to that level of output at that rpm without heating the stator badly at 12vdc output, and likely at 24 vdc output.

would like more details, and stats

bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

fattywagonman

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Re: Pettergens
« Reply #6 on: June 12, 2006, 11:59:04 PM »

Hi Bob here are some answers to your questions.. where do you get your basis for 1.5 kwatt output?
Output varies according to RPM at 850 RPM the output is about 60 volts and 15 amps.. so about 900 Watts

At 1600 RPM the output is about 63 volts and 30 amps.. so about 1800 watts My batteries are not so good I think that's why the volts are a bit high..

did you rewind the stator for higher voltage? Yes

how long did you run at your reported 1.5 kwatt? Several hours

how is the stator cooled at this level of output? Fan on flywheel pulls air through the center.

the original delco stator wont hold up to that level of output at that rpm without heating the stator badly at 12vdc output, and likely at 24 vdc output.

The aluminum plate, housing and fan do a good job of dissapating the heat... After an extended run @ high output the windings are fairly warm.. but no more than  about 160-180 F... 

altopro

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Re: Pettergens
« Reply #7 on: June 13, 2006, 12:49:33 AM »
Hi fattywagonman,

Very nice setup! I think Mini-Petters should deserve more attention.

What size engine is this?

Cheers!

PAT
Pat Ricard
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I do ship to USA

fattywagonman

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Re: Pettergens
« Reply #8 on: June 13, 2006, 01:44:30 AM »
Hi Pat,
This is a 3.5 HP ... I also have some 4.5's on the way... I like the mini's but the 6.5 and 7.5 petters are my favorite...

mobile_bob

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Re: Pettergens
« Reply #9 on: June 13, 2006, 06:49:15 AM »
FW:

i find your results impressive!

it makes me wonder how a stator out of a larger frame motor, rewound and fitting with a neo mag rotor would do.

hmmmm?

damn you! now i have to add this to my things to do list. :)

i have a mini petter, a 2.8 hp a purpose built setup like yours for battery charging would be a nice application for this engine.
and for an offgrid system doing the top off and equalization charge would fit the bill quite nicely i would think.

good job

bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

fattywagonman

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Re: Pettergens
« Reply #10 on: June 13, 2006, 02:50:58 PM »
Hi Bob,
Sorry about that ... I didn't mean to create another project... The folks at Hydrogen appliances are great... they ship fast and I think the prices are fair for what you get... I've tried different windings and the SC24 core seems like  the best for the RPM of the Mini... It is 3 phase wound in delta so there's a bit more amp potential.. I'm working on a 3 phase drive to give electric start capability.. I thought about a larger PM for the standard petters... so far no luck finding anything off the shelf.. I planing on  doubling up a couple of PM's for the standard.. I've also thought about making something like the brake rotor PM's as a low RPM direct drive DC gen for the Listeroid....   

Doug

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Re: Pettergens
« Reply #11 on: June 14, 2006, 02:43:43 AM »
This is all fine and dandy for small gensets that feed power into large sinks like a battery bank but I don't know if there is actualy a need for a large PM alternator. The bigger they get the more unforgiving they become.

Doug

Shadow

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Re: Pettergens
« Reply #12 on: June 14, 2006, 04:44:05 AM »
Here's a link to one the boys over at Otherpower have built and rebuilt a couple times. I guess you could build most any size/voltage you wanted. http://www.fieldlines.com/story/2005/9/20/16716/4310

fattywagonman

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Re: Pettergens
« Reply #13 on: June 14, 2006, 06:22:07 AM »
So far I couldn't be happier with my little minipettergen.. I have a bank of 4 12 v 60 AH  AGM's connected to a trace SW5548 inverter.. Today I doubled up two alternators on a single shaft for the larger 6.5 petter.. I'm also working on a regulator and start circuit.. seems like the otherpower guys needed more cooling.. and I wonder why they didn't just make DC power and use some batteries and an inverter..

Doug

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Re: Pettergens
« Reply #14 on: June 15, 2006, 04:19:20 AM »
Yes I know what you mean fattywagonman:

They should have just bought a generator head...
Or if as you sugest  for charging a large PM motor ( handy if you want something that self starts )

But remeber they sell windmill stuff, and they built a windmill alternator and bolted it to a Petter as much for power as an advertising tool. They like to tinker, no fault with that.

Doug