Motor

On Thursday, December 17, 2015 at 11:23:48 PM UTC-5, snipped-for-privacy@gmail.com wro te:

requires 12V. Motor needs to move 30 degrees after every hour. Total requi red rotation is 180 degrees. Motor starts from zero degree, moves 30 degree s every hour reaches 180 degree and then travels back to 180 degree without stopping and then repeats, 30 degree every hour. I am using 12 V 4AH Lead acid battery,

raws 2A. But it moves for a very little time. How can I calculate that time ?

Use a stepper motor, not a DC motor

I am stuck with DC motor, can not change to stepper now. I am stuck with this problem for couple of days. I will appreciate any feed back.

Total required rotation is 180 degrees. Motor starts from zero degree, moves 30 degrees every hour reaches 180 degree and

then travels back to 180 degree without stopping and then repeats, 30 degree every hour. I am using 12 V 4AH Lead acid battery,

Is this a geared motor? How do you move it only 30 degrees? How many clock pulse of the micro is the motor on. You can't stick a scope on it and see the motor is on for 750ms,

6 times a day and 3.8 seconds 1 time a day. Then calculate from there?m What is the wave form of the current, for a few us the current my be 10 amps, if you pulse it full on.

Mikek

Measure the RPM of the motor while it has enough load to draw 2 amps. Divide 1 by the RPM and you will know how long 1 revolution takes. Divide that by 12 and you will know how long it takes to move 30 degrees. Multiply that by 6 to get total run time per hour. Oh wait, the motor needs some time to accelerate and decelerate. Are you wanting to know how long to keep the motor on in order for it to turn

30 degrees? If so you will need to provide more information. Like the accel. and decel. times. Since you are using a microcontroller you could use it with a couple sensors to measure motor on time. Your question really can't be answered accurately unless you provide more information. If you really can't change to a stepper and want to know how long to run your motor then probably the easiest thing now for you to now is to run the motor for a certain length of time and measure how many degrees the shaft turns. Do this several times to make sure the motor shaft always turns the same amount. Then try a different on time and measure that. Use those times to figure out how long the motor needs to be energized in order for it to turn 30 degrees. Eric

you can calculate it from the speed of the motor.

you said 2A while running.

about 8 hours run time if they only power the motor.

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  \_(?)_

I thought I answered this already today. Oh well -- once more into the breach.

First, speaking about answering this already, you've asked similar questions before. The answers aren't going to change much.

You have not given enough information. The two missing critical bits are, one, how the mechanical load you're putting on the motor compares to it's rated "full load", and, two, how long it needs to turn to travel 30 degrees.

Don't answer these questions and no one can help you. Do answer these questions and a moderately good student in high school physics should be able to answer your questions.

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Tim Wescott 
Wescott Design Services 
http://www.wescottdesign.com

Oh, I DID answer the question, in comp.arch.embedded.

Please don't multi-post!

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Tim Wescott 
Wescott Design Services 
http://www.wescottdesign.com

Don't. Measure it.

Why do you want to "calculate" the time? To achieve position accuracy? If that's the case, what accuracy do you require and how repeatable does it need to be?

Ordinarily you might do something like that with an encoder on the motor or gearbox output.

But if you just need to stop at the same points every time, you can use a cam and "zero seeking" limit switches. You turn on the motor, but the motor turns itself off when the limit switch opens the power circuit to the motor.

Agreed. motors and gearboxes do weird things once you factor in backlash and how they coast.