94Views17Replies

Author Options:

Scientific Theory Answered

I am working on a scientific theory and I need a little help.
I have 2 car batteries in series to create 24v need to power an electric motor.
The motor is 14.5 amps and I need a way to control the amperage from the car batteries to the motor.
Any help would be greatly appreciated.

17 Replies

user
Ice Dragon (author)2012-12-23

to me it is a theory even if it is engineering not science, but to meeven engineering is science based.
OK here is what i need to know: I need to know how/what i can use to control the speed of the motor cuz a potentiometer doesnt work or it blew out one or the other. any more help would be appreciated.
Lets put it this way if i am successful in this theory then i can advance it to power my house without outside power and hopefuly my car without outside power source.

Select as Best AnswerUndo Best Answer

user
caitlinsdad (author)Ice Dragon2012-12-23

Look up rheostats, you are talking mucho power here which would blow out normal electronics potentiomenters without control circuits.

Select as Best AnswerUndo Best Answer

user
Ice Dragon (author)caitlinsdad2012-12-24

ok the motor i am using is a unitemotor model# MY1016 i believe it is a 300 watts motor whould i match the rheostat to the same wattage or more or would a lesser one work?

Select as Best AnswerUndo Best Answer

user
kelseymh (author)2012-12-21

I'm not exactly sure what you mean by "working on a scientific theory;" putting together an electric motor is engineering.

You should not need to "control the amperage" (at least, not if you actually believe in current, well known science). The motor is a resistive load. It will draw ("pull") exactly enough current (14.5 A) to perform its function. The important thing is to be sure that your current source is capable of supplying that current at the required voltage.

In your case, a standard auotmotive battery can certainly supply more than 14.5 A, so your engineering setup should work properly.

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)kelseymh2012-12-22

The motor ISN'T a resistive load......

Select as Best AnswerUndo Best Answer

user
kelseymh (author)steveastrouk2012-12-22

No, it's more complicated (if I'm not completely mistaken, the load goes like I2, not like I). However, I believe that it is still true that the motor will draw current from the source, not that current gets pushed through, which is what the main confusion seemed to be. Given the level of sophistication of the question, I was trying to keep the discussion as simple as possible.

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)kelseymh2012-12-23

Current depends on load. The lower the speed, the lower the back EMF. As I said to Cdad V=IR+Vb.

Select as Best AnswerUndo Best Answer

user
kelseymh (author)steveastrouk2012-12-23

Thanks. As the load and speed increase, so does the back EMF, which increases the current draw. faster than just I = V/R.

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)kelseymh2012-12-23

As the load increases, back EMF FALLS, so current increases.

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)kelseymh2012-12-23

As the load increases, back EMF FALLS, so current increases.

Select as Best AnswerUndo Best Answer

user
Ice Dragon (author)2012-12-23

I thank you all for the comments the reason I said scientific theory is that I am working on a continual power source and I am not a schooled scientest but a rogue scientist. I dont know what all the formulas listed mean, but I might be able to figure it out and ty again.

Select as Best AnswerUndo Best Answer

user
kelseymh (author)Ice Dragon2012-12-23

Discovering new science requires having a thorough knowledge of existing science. Otherwise you waste most of your time discovering stuff that is already well known, or chasing stuff which is trivially known to be wrong.

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)2012-12-23

Well, alright then, it is Christmas....

Select as Best AnswerUndo Best Answer

user
caitlinsdad (author)2012-12-21

Theoretically, V = I x R ?

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)caitlinsdad2012-12-22

Not for an electric motor, V= IR+Vb, where I is the armature current, R is the armature resistance, and Vb is the "back emf" from the wires of the armature generating a voltage in the presence of a magnetic field.

You're welcome/

Select as Best AnswerUndo Best Answer

user
caitlinsdad (author)steveastrouk2012-12-22

Ah, the great scientific formulas of our time always have that unknown constant added to the equation which could be trivial or non-trivial known as the fudge factor. Surely this must be the work of the electrical engineering gods and the question should be posed here.  Please have mercy on us mere mortals and career subatomic particle physicists who surely could not comprehend such greatness.

Select as Best AnswerUndo Best Answer