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Old 11-29-2015, 08:35 AM   #27 (permalink)
serialk11r
Master EcoModder
 
Join Date: Jan 2012
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spyder2 - '00 Toyota MR2 Spyder
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Quote:
Originally Posted by oil pan 4 View Post
Why stop at Schottkying the main rectifier, why not replace the half wave voltage rectifier for the regulator?
That should decrease the RPM at which the alternator comes up to the desired voltage and increase its output.
I like this mod for those reasons.
Those aren't Schottkys, they're active rectifiers like I said! Look at the spec sheet.

And yes, more power from the same alternator particularly at low speed is the strength of this mod.

I took a look at the alternator on my car, it seems to be the 127mm stator 130A Denso "hairpin" wind that is fairly common nowadays, with higher copper fill but normal diodes and giant heatsinks to cool them. All Toyotas use it.

On German cars the standard these days seems to be a Bosch "High Efficiency Diode" (aka Schottky) alternator. A Passat for example has a very short black casing around the end of its alternator due to the lower heat output from the Schottkys.

The benefit of the Denso approach is that at high amperages, copper losses are cut significantly. However at idle, I don't think the alt is pumping out anywhere near half its rated amps, and the voltage drop due to stator winding resistance can't be that high, but the drop across the diodes is huge.

I plan on switching my FRS for something else, so I'm not going to touch the alternator, but I've been looking into hypothetically hybridizing a car and I was thinking that keeping a smaller alternator around for redundancy and extra low rpm charging capability might be a good idea, while shaving off a bit of high up mass from the engine.
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