Everyone seen this? More efficient alternator
 

Alternator 3500 & 6200

If you look at the bottom of the page, these guys claim that the minimum, you'll see a 5% increase in efficiency using their alternator as opposed to the standard kind. Anyone used one of these things? Sounds like it could be well worth it, in the long run.

It might be cheaper, easier and more efficient if you got a 12v windturbine PMA and use that in place of your alternator and under drive it big time.

Kinda heavy.

Photonfanatic -

Cute logo :

http://polarpowerinc.com/images/banner-logo-home.gif

I am in favor of "upgrading" worn out parts with more efficient ones. If there was independent proof of efficiency + fitting in my car + a fair price, I would seriously entertain the idea.

Here are the models :

(45 lbs!)
http://www.polarpowerinc.com/6200_Brochure.pdf

http://www.polarpowerinc.com/8000_Brochure.pdf
I can't tell from the specs, but they seem to be too big for my 8lb/90-Amp alternator.

CarloSW2

The 45 lb 6200 is rated 9 kw or about 750 amp at 12 volt. Might be more than you need.
-mort

At a weight of 23 lbs (3500 series) it seems a bit heavy for a car, but then again I don't believe this is meant for a car. However if you were to use these as the power producer of a genset, which is it's stated use in the article, the high efficiency and the massive power output would make them ideal for an off-grid generator. Because of its 12 pole design, they are also adjustable from 12v to 64 vdc which makes them great for dc charging systems. Plus if it does actually get the claimed 100,000 hour life span, this would be excellent for off-grid. I could definitely see these used in parallel hybrid applications too.

Looks like they are still using diodes. They could bump efficiency a lot more with FETs.

If I ever have some spare time, I'll finish my external alternator synchronous rectifier board that you mount in parallel to your existing rectifier. I have the design working beautifully in simulation.

ConnClark -

Man that sounds like Back to the Future! (Not making fun, it just sounds cool)

CarloSW2

Can you expand upon that explanation? I'm a bit of an electricity noob and what you're talking about sounds interesting. Are you making a way to make the standard alternator more efficient?

23 lbs seems about right for a car alternator; however, I might be missing something here. The various voltages they have listed are fine, but in my experience, car alternators are almost always rated by amperage. That's the one figure I can't find anywhere on their page.

Yes, basically I am making something that will allow you to improve your alternators efficiency.

Ladogaboy -

Yeah, I didn't like that either. mort inferred it for us :

6200 Model :
9KW = 9000 Watts
Watts / Volts = Amps
9000 watts / 12 volts = 750 Amps

When I look at a chart for the 8080 model (13+ lbs) I seek 1 KW at 1200 RPM :
1000 / 12 = 83 Amps

At 2400 RPM I see ~5KW :
5000 / 12 = 416 Amps

Sooooo, there's plenty of juice in them.

CarloSW2

So to sum up..

Could be a little more efficient, but still a little heavy.

Worth it as a replacement if you could get one small enough to fit in your car? Perhaps once your current alternator finally dies, and you're going to have to do something anyway.

Yeah, I was just skimming looking for Amp ratings... didn't think of calculating the amps. :D

Still, I'm not sure how much "better" these alternators are because you are still dealing with the x factor of how big of a load your current alternator is versus one of these. For reference, my car's alternator is 25-30 lbs (I haven't seen any exact numbers and haven't personally weighed mine) and outputs 130 amps.

Theoretically, if one of their amps weighs the same and offers the same internal resistance/load on the engine as my stock alternator, but produces 260 amps in the process, it should half the time the alternator is actually engaged. Right? If so, there might be some benefit, but I don't know if that is enough to justify replacing a currently operating stock alternator...

Alternators are on constantly. A more efficient alternator would reduce the load on your engine. The ability to output 260 amps just means you can add additional electrical devices to your car.

Ahhh, I was under the impression that alternators had clutches much like the compressors on an A/C unit. When engaged, they draw significantly more energy away from the engine than when they are not. Hmmm...

nope thats why some do the alternator kill switch.

Does it work? Seems like it would put your battery under significantly more strain, thus shortening its life. Could get expensive.

It will shorten battery life some. As to whether it works for saving fuel is debatable. For every amp you draw out of the battery you have to put 1.15 amps back in to charge it.

you need to consider the maximum front drive load on your engine. Just because it could put out x amps does not mean you can get it without risking a catastrophic failure.

Bump, @ConnClark what happened with the synchronous rectifier?

I see some driver ICs out there that make it pretty easy to build, but does anyone know of any synchronous bridge rectifiers you can just straight up buy ready to go?

I'm thinking, add 10% more efficiency to the alternator, you get an extra volt or so to play with at idle, so a 10% underdriven crank pulley (maybe just machine the original a little) can be used to slow the water pump a tad (0.9^3 is 0.729, 27% less power!) and the average savings should be something like 200W crank power saved at cruise between the alternator and water pump, which is a solid gain for a reasonable cost vs. buying overdrive alternator pulley, underdrive main pulley, etc. or electric pumps and such.

I got caught in a layoff of with about 1/4 of the company I worked for. I haven't had the means to pursue it further.

Playing with an under drive pulley would throw off some of the benefits of a lower field coil current. There might be some gains to be had though. Its not something thats going to be a straight forward adjustment.

Aw, sorry to hear. What driver and FETs were you using? Mind sharing the schematic? I think a Denso square conductor alternator (~20% higher fill factor) and synchronous rectifier could return a reasonable 70% efficiency which is not too bad.

Yea I realize that, but it's not like reducing load at idle saves much fuel anyways, and even a small reduction in the speed of the alternator and water pump helps a lot for power savings under typical usage and high rpm since power is a cubic function of speed.

Can any people who are good with circuits verify that all you need to build an active rectifier bridge would be comparators and MOSFETs? I really want to try this! Haha.

EDIT: Okay my research brings me to the following specs for a comparator:
Minimum supply voltage <= 6V (so it still functions when the engine is cranking under low battery), max supply voltage >16V (maybe good idea to pick the higher voltage ones to prevent damage from surges?), open drain or push-pull output, and 125C temperature rating.

http://www.st.com/web/catalog/sense_...S1089/PF254080
STMicroelectronics TSX393 fits the bill? 2nA output seems too small, is push-pull better since it has more output current?

@ConnClark

Was thinking about this again recently, and I came across this after many hours of reading:
Diodes, Rectifiers - Single | Discrete Semiconductor Products | DigiKey

Product sheet: http://www.ti.com/lit/ds/symlink/sm74611.pdf

26mV forward voltage drop, 0.3uA reverse leakage, 15A recommended continuous current diodes for $3.69 each! They can take 24A but the voltage drop increases a bit. They're synchronous rectifiers in a single package! The Microsemi chips that are the next lowest rated Vf on Digikey are said to be active rectifiers (LX2400ILG, out of production replaced with the higher rated LX2410A). Those chips happen to also be rated for 225C which is good for an engine bay.

I think my car has a 130A alternator, each phase is putting out 130A at its peak over a brief moment, so it would take 5*2 per phase * 3 or 30 of them :( I don't really see this car consuming 130A but it could probably get close thanks to the electric power steering, though I've probably shaved off around 10A with LED bulbs around the car. With my MR2 and its 80A alternator, using 18 of the chips seems a little more sane.

Anyone want to try these out?

Seems like a lot of maze for very little cheese.

You can get 100 volt 160 amp rated pieces for, not real cheap.
STPS160H100TV

Problem with Schottky diodes is they really don't like to be hot.
Between 50'C and 100'C they lose half their power carrying capacity.

These 160 amp diodes really are only good for 140 amps, if I can keep them at 50'C (as in they can not go in the hot engine compartment).

Typically alternators electronics are rated for up to 200'C.

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.

Seems to me that the only was an alternator with a substantially higher weight makes any sense is if you have...

a. increased battery capacity with the ability to charge at a very high rate

and...

b. a smart charging controller which would allow you to go to a high charge rate when you wanted to slow. MAybe even have the ability to go to a low level of power output when acceleration was needed for short periods

Yep, agreed. I think nowadays they just slap a big alternator onto everything so they don't have to make as many different ones to save cost, and so that the idle speed doesn't have to increase as much for turning on electrical components.

Since there's a battery in the system anyhow to provide intermittent power, it seems more logical to size the alternator for typical operation, which is generally in the 30-50A range I think. If I weren't so concerned about resale value I would definitely try to experiment with a 6-7lb 80A alternator or something like that, because as far as shedding weight from a car goes, 100 bucks to drop 7 pounds off the top of the engine is pretty darn good. Lighter wheels, lighter battery, and lighter exhaust are all around that much or more per pound lost.

If the manufacturers save money using fewer different alternators, are the replacements any cheaper? :)

I am sticking with the big alternator.
Solar doesn't do me any good when its thick over cast and I am trying to run the electric power steering (when I hook it up),defroster, washer fluid, heater and lights or the power inverter.

I have a spare AC delco alt I can take apart to see if its feasible to remove/bypass the existing diodes.
If I remember correctly this alt wasn't coming up on voltage like it should.

I took my old alt apart.
I can completely reengineer this thing.
Convert the stator windings from 3 wire to 4 wire wye. I can see where the wires come together and I can access them.
Whats the difference between 3 and 4 wire? By adding a current carrying neutral wire I can increase stator capacity by about 70%. Decrease the working load on the line diodes.

Then add a PWM controller or resistor to the Vreg power source to slow the charging rate if I want to.

Add a pot to the Vsense terminal to turn up the volts if I so desire. On the big old generators which had a voltage reg not so unlike this one they typically used 0 to 50 ohm pots to fine adjust the voltage.
So I figure stick with what works and get a 0 to 50 ohm pot to put on there.

The wires that make up the stator are 16 or 18 gauge, so there is no way each wire is holding 100+ amps RMS. Those wires would just melt.
20 or 30 amps per line max (if it were to stay a 3 wire).

I ordered 25 of those Texas instruments Schottky diodes. $90 after shipping and sales tax.
All I can do is give it a try.
There might be a few other projects I can try them on so I ordered some extras.
It looks like their normal application is solar panels. When I get solar panels in I take off reverse blocking diode. Because I use a charge controller and I am not worried about losing a little bit of power if some of the panels become shaded. I would rather get that extra half volt all the time and lose a few watts some times when some panels become shaded. Instead of losing that half volt all the time, just to save a few watts if some panels become shaded.

A more economical solution for under driven alternators might be to just install 3 of these shcottkys between the stator and the voltage regulator.

I think the most cost effective way to do this if you don't want to cough up the money to replace all 6 diodes is to replace only 3 of them. That cuts the voltage drop in half, for 20-30 dollars. Should give an extra bit of power at low speed.

explanation
 

GOOGLE: Field-effect transistor
look at MOSFET and IGFET.
Very efficient,low loss power transfer

I am thinking take this:
http://ecomodder.com/forum/attachmen...1&d=1449114386

And modify to this:
http://ecomodder.com/forum/attachmen...1&d=1449116010

I will be putting the rectifiers out side of the housing, outside of the hood where they can stay cool since these schottky diodes are only rated to 125'C and things that alternators are typically made of are rated up to 200'C.
Silicon diodes are good at elevated temperatures.

VR is where I can fine tune the voltage at the battery with the Vsense wire.
Vsense is for use with the LiFePO4 and power inverter setup, to provide boosted voltage level at point of generation to provide proper voltage to the battery during heavy inverter use.
The switch labeled swF kills power to the exciter field.
In the stator I will utilize the 4 wire wye configuration.

Have you tried the folks in the Paul and Sabrina's Cheap 3 Phase Inverter (AC Controller) with Field Oriented Control thread? Or Open ReVolt: open source DC motor controller? They live for that stuff.

I got the diodes in and they are tiny.
This will make heat sinking them a little more difficult.
They are about the size of a single 555 timer.

I think my best chance is to solder up the 4 wire bridge rectifier which is going to be a mess and encapsulate it.
I have some leftover silicone based solar panel epoxy I could use for this.

The way I figure it each of the 4 wires will have to handle about 35 amps RMS at full power. So each wire that will be soldered into to the alternator windings will be at least 12 gauge.
Which is what I see a lot in vehicle alternator to welding alternator conversions.

Old thread but I was thinking about this again today, even though I have no car. I was thinking how I'd hypothetically go about increasing alternator output for minimal effort if I were to change a bunch of accessories on an older car to electric.

I noticed it's pretty easy nowadays to find pretty low RDS_on MOSFETs with synchronous rectifier controller on a board like this: https://www.ebay.com/itm/15A-50A-Ide...e/153280765383

At 1.5mohm, you're looking at about 0.34V drop across two in series, and 40W/6=6.666W heat dissipation at 120A output, which seems manageable with some small heat sinks.

I'm not sure if those switch fast enough though. An alternator at 16000rpm with what, 6, 8 poles? would would switching at about 1000Hz. I kind of ran out of energy looking at MOSFET specs trying to figure out if the gate capacitance would be an issue.

There's also this: https://www.mouser.com/ProductDetail...020DyZ8w%3D%3D

It seems like it can handle 80A at 50% duty cycle square wave, equivalent to 80*sqrt2=113A continuous in terms of heat dissipation. A 150A rated alternator would see a 106A amplitude 50% duty cycle square wave which is below that, and the voltage drop across two of these things would be about 0.6-0.8V, which is not too bad. Since they're less bulky, wiring them up might be easier, but they need more heatsinking.

In the second case, the voltage drop is being cut by a bit over 1V compared to a normal alternator rectifier. That gets probably something like 10A for free, which is just about enough for an electric power steering pump at idle + electric water pump :)

Tvago was working on something like this but he has not been active for some time.

Chevy Tahoe alternator from 2008 and up has manual power control (elerto magnet )