NLang

iTrader: (12)

I'm going to try to use an electric motor to turn accessories instead of running everything off a crank pulley. Why? Though that should be obvious, why makes no nevermind...

Problem: how to get the electric motor to increase rpm with the engine. I need to figure out how to read the speed of the crank, and use that reading to increase and decrease voltage to the electric motor per the crank's speed.

Possible options @ first thought: crank trigger, or tap into the crank or cam sensor. But, I'm stuck with using, transforming, and applying a signal.

I should've went for an EE degree instead of a ME degree We could probably make custom pistons in-house, but I'm lost with something like this

wait4me

iTrader: (10)

would it matter if the accessorys stayed at a steady 3000 rpms? i wouldnt see that bothering anything, so all you need to do is pulley a motor so everything just runs at that speed all the time when the motor is running.

NLang

iTrader: (12)

The dry sump pump, and alt will need to vary with rpm. The water pump could turn @ a constant speed, but that's it...

wait4me

iTrader: (10)

alt can be the same speed, it is voltage regulated and will put out only what is needed right?? so it can stay the same speed, hmmm the sump pump,,, i would say a tps sensor, and just use the 0 to 5 volt output but change it to a 12 volt output, from the reference input on it, but then you would need a bunch of electronics just to make it not burn up a pump by not having 12 volts to run all the time, you would need to somehow make it an amperage adjustment and not a voltage one... ??? man, you ask hard questions.. there are outputs in the computer, maybe using one that normally controls the pressure modulator in the trans to add and subtract the amps of the motor, kind of like it does with the trans pressure??? ohh my. jes

NLang

iTrader: (12)

M6=no trans pressure modulator RPM's can vary too much with the same throttle position so that wouldn't work either. There has to be a way to 'observe' maybe the crank sensor's readings w/o drawing current, and then use that reading to 'command' a specific amount of current to the motor per its readings. I just don't have the background in electronics to 1-figure up a way to 'read' the signal and 2-use that signal to operate some sort of switch that would regulate current to the motor.

It'll be another couple yrs before I'll have enough spare time to dig deep into advanced electronics (an interest growing daily). I have some of the basics from my ME journey, but we didn't cover much. Just what was required to get to a later chapter on ME.

ataylors

iTrader: (2)

what about using one of those fuel pump boosters to vary the voltage to motor? The work off of load correct?

NLang

iTrader: (12)

The pump is for sure voltage sensative. I'm not sure how I could get what I'm after with its signal though

ataylors

iTrader: (2)

what I was thinking is that you could hook the booster up and then have the output voltage go to your motor. as engine load increases then the booster would increase voltage to your motor thus increasing its speed.

NLang

iTrader: (12)

Good deal. I'll go dig into some fuel pump booster specs. Thanks!

383LQ4SS

iTrader: (33)

Maybe IM missing something.....You may as well delete the alternator and run high voltage race battery for 1/4 mile runs.
If you succeed in running your alternator with an electric motor and producing more power than it takes to run the motor...then you are a genius..and the inventor of a perpetual motion machine.


The alternator must be hooked to the engine by some means. It cannot be driven by an electric motor that will be consuming electricity from the alternator its spinning.

NLang

iTrader: (12)

This engine will see the top end for prolonged periods of time. That's what got this going. @ 7500-8000, sump/vac pumps place one hell of a drag on an engine-somewhat defeating a main purpose. Then there's the drag of the high volume water pump and the rotating mass of the alt. You can imagine the amount of pwr robbed @ 8k. It's more than enough to atleast attempt this. The objective isn't to create more amperage than is required, just enough...If we burn up a battery every 1k, what's $60 for another with such a pwr and spool-up advantage...

Sure it can. The amperage of the alt. is the determining factor. You can have them built up to 300amps making only a slight increase in drag.

Don't take this the wrong way, but anylizing anything but the loose ends above (the high points of this thread/my inquiry) isn't going to get anyone anywhere-on either side of the coin...There are ways of making this work. Everything was anylized prior to even taking such a project seriously myself. The single dissadvantage is the weight of the motor. @ 24xxlbs raceweight, we can afford it...I'm just lost at where and how to take a reading that varies with engine speed, and using it to vary the speed of the DC motor on-key with that reading.

To be certain we're all on the same page, no flames to anyone here at all. I'd just like to keep this on topic.

NLang

iTrader: (12)

I got to thinking about something while studying-up on circuitry last night...The alt varies charging amperage with rpm. If the alt itself was tied into the engine (via belt), would it be possible to tie the DC motor directly to the alt to somewhat accurately increase/decrease its speed? The input amperage would obviously have to be regulated to some degree per the motor's requirements.

EDIT: I guess that'd make it AC then wouldn't it...That would for sure open up motor availability

NLang

iTrader: (12)

Anyone else have an idea?

jimmyblue

iTrader: (11)

You want to pulse-width modulate the motor establishing
a varying voltage, is how I understand it. This should be
pretty simple if you like hand building electronics. You want
a comparator like a LM339 or similar, something that is
overvoltage tolerant and will not load the tach line to pick
off the signal. You want that to drive a one-shot (monostable)
with a pulse width set such that (say) 6000RPM (100Hz?) will
produce full-on (the pulses just run together). I do not know
the tach signal basis other than that it's a square wave.
Anyway, that fixed-width, variable frequency pulse becomes
a pulse-rate-modulated (not PWM but close enough) output
whose value when averaged is RPM proportional. Now you want
a low side power MOSFET driver and a good high current, 100V
NMOSFET to drive the ground side of your motor with the IGN
side connected solid. Probably need a freewheel diode though
modern FETs often have good enough ones internal (check
the ratings). Badda-bing, an evening of soldering up piece parts
and an evening of figuring out why the first try burned up, and
you're in like Flint.

NLang

iTrader: (12)

Much appreciated I'm going to have to wait and try to toy with that tomorrow. I lack the background/electrical schooling to translate it, let alone dive in and get soldering

EdmontonSS

There's no doubt there is no point in running the alternator off an electric motor. If I were you (I'm not! I know...) I would leave the alternator on the engine or remove it completely for a track-only car. I would find what minmum RPM's the water-pump, dry-sump etc. require at max RPM's to keep the engine lubed and cool, and just size pullies for that RPM on the accessories with a constant RPM motor, keeping in mind a DC motor is going to slow down with load and voltage drop from the battery/ies you'll be using (saftey margin). A VFD would be nice and very easy for someone with an electronics background to make work off of any number of engine sensors... But if this is an all-out race machine, I imagaine you'd be demanding max output from your electric driver most of the time anyway...

SmaknaSS

iTrader: (1)

Instead of building a PWM drive, You can purchase an inexpesive drive from KB electronics then slightly modify it, I beleve they manufacture 12 and 24V PWM drives. I personally would keep the alternator on the car to run the accesories. Here is the address to the KB electronics site,just cut and paste this: http://www.kbelectronics.com/

Technoman64

iTrader: (6)

Learn electronics and do the math. It will take more away from the battery to run the alternator with an electric motor than if you just did not have an alternator on the car. If it were me I would run the alternator from the engine. Use a RPM switch to disable the charging field above a certain RPM or reduce it to just what is needed to maintain the battery. Freeing HP at upper RPM. Then run the remaining items from the electric motor. This will keep the battery charged and free HP.

Also you can reduce the RPM of the alternator with pulley kits to help the upper RPM.