Alternator Delete VS starter motor - Page 2 - Fuel Economy, Hypermiling, EcoModding News and Forum

bennelson · 08-21-2008, 12:51 PM

I have often heard that you only need about 8 hp to go 55 mph.

My motorcycle is using a 8 hp continuous electric motor. It is geared for 45, but a gear swap would let me go 55.

Who needs 100 HP really!

Yeah, I am not saying turning off DRL will save a ton, but every little but helps!

Daox · 08-21-2008, 01:54 PM

This is a spreadsheet I made up a while back using information from an autospeed.com article. It estimates how much HP you need to go a certain speed. Its not incredibly accurate, but it gets you close. Just fill in the yellow cells to get your answer.

HP_at_Speed_calc.xls

orange4boy · 08-21-2008, 07:55 PM

I'm running two Deep cycles and just drove from Vancouver to Seattle in my Previa. Batts were at 60% DOD when I got there. This included about twenty starts in the border line up (45 minutes of idling saved) They are used series 27 batteries @ $50 ea. from a local shop.

Another thing to remember is that your alternator is also charging your battery. It has to recharge each time you start and trickle charges constantly. I have never seen a battery take less than 3 amps after sitting overnight and it would be much more after you just pulled 400-500 amps to get it going. All this at a time when engine is cold and running rich.

Now that my Previa is alternator free it starts easier , has more pep and revs quicker. Not to mention getting 26 mpg highway (20mpg EPA)

Read what the experts have to say about alternator loads:

IEEE Spectrum: Automotive Electrical Systems Circa 2005

Cut that gas hog out of there.

P.S. Guess who was instrumental in getting DRLs into cars? (Hint: EV killers)

G.M. *******s.

modmonster · 08-21-2008, 08:21 PM

heres an idea. the alternator is controlled by voltage. if we have an alternate charge source to the alternator then the voltage will go high and the alternator will switch off eliminating parasitic load. all we need is a big 110v battery and a charger. we can control the rate of charge with a resistor (light bulb) in series with the car battery or the internal resistance of the battery itself. we don't even have to supply all the amps -if the voltage drops the alternator will kick in.

orange4boy · 08-21-2008, 08:50 PM

Not a bad idea if you don't want to remove your alt completely

If that's true, you would reduce the electrical load on the alternator but the belt still adds some drag.

Two 8 volt golf cart batteries in series would net you 16+ volts. You would have a good buffer until the alt kicks in.

There are also 16v racing batteries for just this application (they know how to get every bit of efficiency) but I don't know if they are deep cycle or not.

P.S. you don't want your alternator to try to charge a deep cycle battery!!!! You might burn it out trying to supply all those amps.

modmonster · 08-21-2008, 09:00 PM

i have loads of batteries from my electric bike i may just wire them all up for 144v then put that through a switched mode power supply to get down to 15v. alternator switches off at 14.5v so i should be able to direct connect them without problems. diodes in the switched mode supply will stop alternator charging anything it shouldn't. i have every thing i need already. just need to find a battery +ve and -ve inside the driving compartment or push a wire through the fire wall.

johnmyster · 08-21-2008, 09:48 PM

Quote:

Originally Posted by modmonster

heres an idea. the alternator is controlled by voltage. if we have an alternate charge source to the alternator then the voltage will go high and the alternator will switch off eliminating parasitic load. all we need is a big 110v battery and a charger. we can control the rate of charge with a resistor (light bulb) in series with the car battery or the internal resistance of the battery itself. we don't even have to supply all the amps -if the voltage drops the alternator will kick in.

Um, is someone suggesting a pulse and glide alternator? I don't understand.

johnmyster · 08-21-2008, 09:52 PM

Quote:

Originally Posted by orange4boy

Now that my Previa is alternator free it starts easier

This is one of those moments where I call BS for one of two reasons. Either to remind the population that not all cars work the same, or to put some real, hard data out there. This data point is slim.

The field coil on my alternator is controlled by the computer. The field coil is not activated during starting. If I were to observe faster starting during alternator disconnect, it would perhaps be due to what I call the "hydrogen generator placebo effect." Clearly it would be my active and optimistic imagination.

orange4boy · 08-21-2008, 11:44 PM

Quote:

Originally Posted by orange4boy
Now that my Previa is alternator free it starts easier

Quote:

This is one of those moments where I call BS for one of two reasons. Either to remind the population that not all cars work the same, or to put some real, hard data out there. This data point is slim.

With two big deep cycle batteries behind it...