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Captain $hit disturber
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Discussion Starter · #1 · (Edited)
I have in my possession 2 eagle auto 275 amp alternators and 3 Tenney 300 amp alternators. Yes I jumped on the Tenney craze and got hooped like quite a few ppl. At the expense of a blown treo 1500.1 I realized my tennys were Hooper and put out shit for current. Shopped around and was like f*** it and bought a cheap eagle auto 275 amp ad244 alternator. I currently have 1 Tenney working at the 2 eagles are working fine :) after about a year.

So here's my deal. I have a total 5 h/o alternators that have internals that I am curious what makes them different then the expensive brands.

I'm going to clamp the 3 alternators that work, each under load via a 500 amp load tester and clamped properly with a dc clamp meter.

I know my intro is very lengthy and wordy but please bare with me. I've also noticed a few things about some brands that I've stolen off Facebook pics and stuff that I will share with all.

Video results:
Tenney:
269 @2000 rpm
161 @ 800 rpm

Eagle auto 2:
255 @ 2000 rpm
145 @ 800 rpm

Eagle auto 1:
240 @ 2000 rpm
125 @ 800 rpm

Tenney #2
170 @ 800 rpm
257 @ 2000 rpm

Alterstart (load boss)
254 @ 2000 rpm

Clamp tests:
Tenney at idle about 900 rpm
www.youtube.com/watch?v=_Q2NIVb3t_I&list=UUq1w2QZyQTLIY-Euanp9_Og

Tenney @ 2000 rpm
www.youtube.com/watch?v=vtiRrnpg_Cw&index=2&list=UUq1w2QZyQTLIY-Euanp9_Og

Eagle auto #1 at idle
https://www.youtube.com/watch?v=VNHFkdHBjts&index=5&list=UUq1w2QZyQTLIY-Euanp9_Og

eagle auto #1 @ 2000 rpm
https://www.youtube.com/watch?v=JgtaETMHfzM&index=6&list=UUq1w2QZyQTLIY-Euanp9_Og

eagle auto #2 at idle
https://www.youtube.com/watch?v=2PvVdTjz_tg&index=3&list=UUq1w2QZyQTLIY-Euanp9_Og

eagle auto #2 @ 2000 rpm
https://www.youtube.com/watch?v=nZuru4wDnFM&list=UUq1w2QZyQTLIY-Euanp9_Og&index=4

Tenney #2 idle
http://m.youtube.com/watch?v=P9mCn39WKQw

Tenney #2 2000 rpm
Http://m.youtube.com/watch?v=51njgxu9Coc

Alteratart/load boss 2000 rpm
http://m.youtube.com/watch?v=Dtz4POIlCYc
 
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Captain $hit disturber
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2,332 Posts
Discussion Starter · #3 · (Edited)
MECHMAN ALTERNATOR VS the other guys - YouTube

Posted link so I would forget lol. He states a couple interesting things in the video. Externally regulated looks easier to switch to then what I thought. They use a standard gm rotor. And their magical aluminum pulley leaves 2 mm gap so belt won't slip. But a cheap $3 pully you can't space with a washer lol
 

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Captain $hit disturber
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2,332 Posts
Discussion Starter · #5 ·
I also have some pics I've stolen over the years but can't upload via mobile gotta wait till home with wifi.

Also please not I'm not an expert nor claim to be. I'm not claiming to have any special insight to how an alternator works. I own a clamp meter load tester and a soldering gun lol high wattage one cause desoldering alternators with a soldiering iron don't work lol
 

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14,115 Posts
DC current from thethe field wire (or regulator) causes the rotor to become an electromagnet, the magnetic waves (flux) runs through the outer windings and makes AC, then the AC is converted to DC via the diodes on the bridge. More wire on the rotor and stator (like filling the gap of a sub ) the more efficient and better potential output. Hair pin allows for a very tight pack like edge wound coils but can't be hand wound like standard stators thus cost more. Higher powered diodes increase efficiency and provide a more stable output
 

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Captain $hit disturber
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2,332 Posts
Discussion Starter · #7 ·
Thanks Jeff. That's how an alternator works. But what I want to know is what separates a stock alternator cheap high output alternator to an expensive high output alternator.
 

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Thanks Jeff. That's how an alternator works. But what I want to know is what separates a stock alternator cheap high output alternator to an expensive high output alternator.
Well stock and cheap can be assumed the same with minor changes such as smaller pulley or paint

High outputs will have a better weave/wind pattern to increase winding density to capture more flux lines. Diodes will be larger to match. Stator will be wound tighter packed... rectifier bridge will likely have better cooling
 

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Captain $hit disturber
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Discussion Starter · #9 ·
Okay well thread is useless now Jeff has covered all I was trying to say. Thanks Jeff won't have to test anything now
 

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When I was tearing down an alt I had better luck using a propane torch than I did the 100 watt soldering gun. I'm planning on doing some comparison between an eagle 200 amp and an aspwholesale 240 amp rebuild. My current measurement will be a 500amp shunt in series with the output with an analog meter. Load will be my actual amp / sub combination. Still trying to figure out how I'm gonna mount the shunt to keep it from floppin around and shorting on anything. I noticed that the aspwholesale stator has 2x the copper that the eagle has (I think the eagle is a stock ad244 stator)

The first eagle 200 I killed, I put an aspwholesale 240 amp stator and a new regulator in. It worked for like 5 minutes, and died again. I think reg died again. Anyone mind measuring the dcr across rotor coil? I'm seeing about 2 ohms on mine, Don't remember off hand.

Long term idea is to build my own external regulator to control multiple alts, use current shunts for monitoring and balance load across alts. Will likely use an N channel mosfet to PWM the field, with the + end of field switched via relay to +12. If going that far might as well incorporate an hd44780 LCD to display currents / total. Will need an adc channel for each alt, and one for v sense, and a PWM output for each alt. Big ideas, little free time to make them happen.
 

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What'd be nice is a t-fade style test on some of the various HO alt companies. Say a singer vs a DC vs a Mechman. It would vary from car to car on who has the better alt in some cases possibly, but still a nice test to see for someone who has the cash and tools lol. Comparsion to the stock alt and potentially a cheap "ho" one with basically just a smaller pulley would be nice as well.
 

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Captain $hit disturber
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Discussion Starter · #12 ·
Drunken you got a pic of that asp ho stator some where? I have a name brand ho alternator on the way. If sombody wants to donate some $$ I'd buy another one lol. But yes a controlled tfade style test is what I'm going for. Tfade the new standard of testing
 

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Captain $hit disturber
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Discussion Starter · #16 · (Edited)
So i got a chance to tear down two of my non working alternators. They are both a mis mash of either tenny parts or eagle auto electric parts.


Tennys' choice of regulator

(12 Volt, B-Circuit, P-L-F-S Terminals, 14.8 Vset, 2.5 sec. LRC)

Eagle Auto's choice of regulator

(12 Volt, B-Circuit, P-L-F-S Terminals, 14.8 Vset, 2.5 sec. LRC)

This is a shot of an Eagle Auto's rectifier, first one i bought came with this copper one and ordered second one and the second one came with a cheap aluminum one. Emailed them and got no response

Found this picture on the net from a company that has been building alternators for 20+ years

Looks very similar to my Eagle Alternator
http://www.aspwholesale.com/index.php?act=viewProd&productId=8705
And the link to the exact rectifier

And did a quick 2000 rpm pass with each alternator


Old pic of the setup back when I though all 3 Tenneys worked
 

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Captain $hit disturber
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Discussion Starter · #17 ·

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What did you use to get the nut holding the pulley in place off? I'm debating whether to buy a new impact or a set of offset wrenches.

And ideally the voltage would stay up while doing full current, but I believe due to resistances involved and the fact that everything is being pushed to it's limits, the voltage sags while moving that much current. That is one thing I've wondered about with the HO alts, sure it's moving 300 amps, but what's the voltage getting down to in order to do so? Also with batteries and their CCA ratings. I think the rotor is pretty much run at it's point of magnetic saturation in order to hit those current levels, so it's at a point where adding more voltage or turns to the rotor's winding won't yield any more field, just more heat. I believe adding more mass to the rotor's core would raise it's point of saturation, like moving to a larger transformer core. I'd like to eventually learn more in regards to magnetic saturation and core structure and all that. Would like to know if putting more current through the rotor would be worth it, re-winding it with a larger wire. Then comes the question of how much field current the regulators can handle. I think it will be a good idea to put the scope to the regulator's field output to see what kind of regulation it uses, whether it's analog or pwm, and I'd like to know if putting a simple buffer using a P channel mosfet and an inverter to drive the gate off of the regulator's output would yield any gains, in either stability, output, or longevity of the regulator's lifespan. It seems like it would at least keep the regulator running cooler since it's not conducting all of the field current itself, but it would require external components to the alternator housing. Another thing I want to do: Ammeter between regulator and rotor. would like to see just how much current it takes to keep the field energized while running full tilt.

Sorry, this post kindof turned into a ramble. Hope it at least inspires some new thoughts :)

Do the 2 alts you tore down appear to have stock rotors?
 

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Captain $hit disturber
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Discussion Starter · #19 · (Edited)
yeah the two rotors i have sitting there appear to be stock.

They both read 1-2 ohms off the slip ring. However i do believe one to be fukked so reading probably wrong.
One on the left is Eagle Auto Parts. On the right is a Tenney

i dont have a stock one to compaire to. Going to go to scrap yard and grab one will be good for compairson. Getting nut off i just use my cordless impact never had a problem.
 

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This is interesting, because I'm curious how DC Power always has those incredibly high idle alternators while mechman never seems to have them. And yet they seem to cost around the same price. Or for at least the few cars I have owned anyways.
 
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