Alternator upgrade

[oil pan 4]

I really like the idea of the http://ecomodder.com/forum/showthrea...tor-33199.html and its low cut in voltage.
The wye wound 10 and 12 series SI alternator have a fairly low cut in speed in factory configuration, between 1000 and 2000 RPM. With my mods, a little lower.

But sometimes solar panels and a little alternator just don't cut it when you just need almost unlimited power. Like a bond villain.
The 1950s design SI series alternator was never intended to run an air compressor, electric pumps, a power inverter powering a welder, hydraulic power unit, light bar or charge LiFePO4.

I would like to upgrade the suburban alternator to my special oil pan 4 blend of CS144 or AD244 alternator. A stock AD244 alternator can make 250 amps, a stock CS144 can make 140 amps. But they are delta wound and don't cut in until over 3000rpm.
Then was thinking my only accessory in the suburban will be the alternator. So I could put in a second one. The gigantic AD244 alternator will take around 4 horsepower to free spin at speed so I will just leave the belt off it and powered down until I need it. All I would need to make it fit is a bracket and some wiring both of which I can do.
The stock pulleys would over drive the alt by about 1:3.

My special blend alternator would be externally rectified and regulated with a max of 10 amp of field current, with provisions to turn it into a DC welding alternator.

[serialk11r]

I've looked into Schottky diodes, they only barely give you any improvement because the higher reverse leakage will eat away some of your voltage.

The right way to do it is an active rectifier, use a bunch of big MOSFETs driven by a synchronous rectifier circuit. Depending on how much MOSFET you have, the drop can be cut to a fraction of a volt.

I think the larger Denso square conductor alternators that are pretty common nowadays can push 200A+ if modified. They have 40% lower copper loss than other alternators. Using active rectification on that would work well.

[oil pan 4]

These Schottky diodes are kind of funky, more like a smart blocking diodes, a diode and a transistor or MOSFET. They are for a solar panel application, where you want low forward voltage drop and very low reverse leakage.

This big alternator thing is going to be made for occasions where I need brute power. I am thinking I will use a 500 amp silicon diode based brick bridge rectifier heat sinked to my stainless steel bumper.
With an external voltage regulator that can put out 10 amps of field power it could potentially make up to 280 amps.

The problem with sustaining high alternator output is the alternator and how over engineered they are, you have the stator putting off heat, the bridge rectifier putting off heat plus blocking air flow and the voltage regulator caught in the middle of all of it. I am going to reverse engineer it, spread everything out so the alternator doesn't turn into a little oven and cook its self to death.

Since the big alternator isn't going to be used most of the time it doesn't have to be super efficient.

Yeah maybe I could find a stator wound with square magnet wire, that would be pretty interesting.

[redpoint5]

If the vehicle is left to idle while powering a 4hp alternator, then expect the cooling fans to be working overtime to keep the coolant temps in check.

[oil pan 4]

That doesn't sound like much of a problem.
Plus can only suck down 4hp at much higher speeds than idle

[serialk11r]

Oh I see, you do have active rectifiers! I found them online and posted about them here a while ago, just wondering, was that where you got the idea?

I hate how these beautiful Denso stators are hobbled with large voltage drop diodes, but I am preserving this car for resale value so I can't touch it.

[oil pan 4]

I thought I linked that http://ecomodder.com/forum/showthrea...or-19986.html? thread where you came up with the idea of using those diodes.
Well it didn't before, but it does now, check out the bottom of post 1 in http://ecomodder.com/forum/showthrea...tor-33199.html .
For some reason I find it important to post the origin of an idea so people can go backwards or forwards in time to see something develop from one thing into that thing or something else entirely.

[t vago]

Whatever happened to ConnClark's alternator rectifier? Wasn't he working on something that would have used PWM to increase alternator efficiency by 5 or 10% or something.

[serialk11r]

Originally Posted by t vago

Whatever happened to ConnClark's alternator rectifier? Wasn't he working on something that would have used PWM to increase alternator efficiency by 5 or 10% or something.

ConnClark linked the paper that uses PWM with a higher voltage to increase alternator efficiency, but he was working on just replacing the diodes with active rectifiers, I think.

Using active rectifiers alone should be worth perhaps 10% more power out for fixed mechanical power to the shaft, around 6-7% for the reduced voltage drop, and a bit more from lower field current and iron losses.

The PWM idea is very cool, but probably hard to do in practice since you have to tweak the voltage regulator AND smooth the output.