I gave up on eliminating the alternator a while back when I seen the 16volt batteries were extremely heavy and over $1000 for just one... Plus having to charge in between every run, and trouble starting, ect...

So i decided to run a small light weight aftermarket alternator. But I thought to myself recently after installing an electric drive motor to run my water pump on my street car, why not run one on my alternator. Mr.Gasket sells one with a 40% over driven pulley (which is what is use on my street car to run the water pump).

How much HP does the alternator drag really cause at high RPM? This is for an all motor car.

 

The motor required to drive the alternator will consume more power than the alternator will produce.

 

Most stockish rotaries idle at around 1000rpm or under. The motors will rotate whatever it is connected to at around 1500rpm. And 40% higher with the over driven pulley which makes it 2100rpm.

I fail to see the difference. As long as it's turning, does it really make a difference? Many people already run these on the water pump including myself...

 

Think about what you're trying to accomplish. You want to use electricity to turn an electric motor to turn the alternator to generate electricity.

 

The more electrical load you put on the alternator the harder it will be to turn. If you could figure out how to run an alternator with an electric motor and have enough energy left over to power the car you will be the richest man alive. It's called perpetual motion and it has yet to be achieved.

 

Ok, I should have been more specific on what I was asking. This was my only real question from the 1st post:

"How much HP does the alternator drag really cause at high RPM? This is for an all motor car."


I was not asking if using the electric drive motor will work, because I know it does. After thinking about it, I did some research and found that people have already done this. I even have a picture of this exact set-up on a 13b drag car on nitrous...



And let's keep the internet fad photos out of the Drag Racing section. Save those for kids in the lounge please.

 

I would imagine it would take 1-3 hp to drive it at RPM.

 

And to answer the question directly, the power needed to drive the alternator at ANY speed is directly related to how much power it is generating. (Underdrive pullies, for example, will have zero effect on parasitic loss on the alternator, as the torque to turn it goes up as RPM goes down, for any given load)

An alternator generating no electricity takes only as much power to turn it as bearing drag requires. If it's generating, say, 53 amps at 12 volts, then that's 746 watts which is one horsepower, BUT since energy conversion is not perfect, it will be double that or so. A constant-duty 2hp motor is not small or light, and it will draw a hell of a lot more than 53a @ 14v...

See, this is why you can't make a perpetual motion machine.

 

How funny would it be if someone actually figured out a way to do this efficiently. You'd probably here something like this.

"HEADLINE"
Garage mechanic on Mazda forum solves energy crisis! The user who goes by Sen2two has succeeded where Einstein failed.

LOL

 

Thank you for the help. This was the exact answer I was looking for...

 

I'll work on it as soon as I'm done with this solar powered flashlight I've got that uses the bulb to excite the solar panel.

 

You finally got it to work! Cool! I'll drive over to check it out. While I'm there I'd love to talk to you about my new idea! Direct Exhaust Injection!

 

This is similiar to my waterwheel pump in my fish tank...the wheel drives a pump that lifts the water to fall on the water wheel. Its been working for months now...I even have pics of it.

 

Would it be possible to disconnect it right before a run, through a switch to cut the drag it causes?

 

Yes, I have seen that before as well.

The electric drive motor works on the alternator also. I just proved it to myself in my garage.

I should have known better to post something new and out of the box on a forum. I thought the kids stayed out of the Drag section though...

 

I dont think anyone is denying that an electric motor will drive an alternator to create electricity...I've also seen it work, but if the alternator is creating the same electricity that eventually powers the original electric motor, your going to run out of power pretty quickly.

A similiar, but more feasable, idea would be to have a clutched alternator that disengages momentarily (for the drag run). Maybe installing a switch to interrupt current in the field winding.

 

 

Before I get sarcastic, I'd like you to genuinely consider this. If electric motors could drive a generator, and create excess (NET) power, why would anybody use a fuel-powered generators? Power plants would not be using nuclear or fossil fuels, and there are teams of scientists that would break that dependency if they reasonably thought it was possible. The reason it doesn't work is that the motor and/or generator (alternator) would have to be better then 100% efficient. Which they aren't.

Now, as far as your panties being in a bunch, if you had taken time to read the first response, and actually thought about it, you'd realize that this idea is neither new nor currently feasible. Then this thread would have been saved the entertaining pictures, which I'm really glad it wasn't.

I like the idea of the alternator on a switch though, just take the load off of it during your run, the only drag would be from the bearings and would be negligible. My only thought would be that going from 13-14V with the alternator on, to 12-13V with the alternator off would throw off your fuel maps if there wasn't the right dead time compensations...

 

Ibtl.

 

^lol

 

Could you please post it?

 

Well, those kids obviously went to primary school where they learned, that no machine is 100% efficient and even if it was, then all produced power would be consumed to power this device itself ie no net output.

Or maybe just everything bolted to rotary engine denies laws of physics

 

Ok, now that pic is is funny...lol

 

I recently removed the motor to drive my water pump and ran that back to the crank. Then hooked it up to my alternator. Let the car idle for a few minutes than drove it around a little. Checked the battery voltage before and after with no change...

Will it work on a daily driver...? Most likely not. Will it work on race cars, I know it will. The power draw from these motors are so low it shouldnt effect anything. But with a daily driver with radio, a/c, lights, ect. it might just be to much. But on a race car, especially if it's a carbed distributor type set up, it should be plenty fine...


It's a small pic, but it's there... (not my car)

 

After you get it started, disconnect the battery and see how long it runs off the alternator and electric motor alone.