How does a motor charge a battery?

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Old 02-12-19, 03:27 PM
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How does a motor charge a battery?

Iím just trying to do a little project. The idea is to have a battery run a motor that turns a wheel. The wheel has a chain going to the motor/generator that then charges another battery. My question is how is the motor charging the battery and not having the battery running the motor. I read that motors can be turned into generators but how can I turn the motor and charge the battery. Wouldnít the battery as soon as itís plugged in start running the motor. Do I need something in between. Any help would be appreciated!
 
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Old 02-12-19, 04:35 PM
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Normally you'd use a charger to charge a battery and not rely on only a motor acting as a generator. Your car has a voltage regulator to control the voltage to allow safe battery charging.
 
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Old 02-12-19, 04:41 PM
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You're looking for perpetual energy. It doesn't exist.
You can't have a battery running a motor driving a load and then also charging a battery.
 
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Old 02-12-19, 04:58 PM
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You can't have a battery running a motor driving a load and then also charging a battery.
I'm not an electrical guy but I think you can but it will eventually run out of juice as the electrical inefficiency and friction soon take their toll!
 
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Old 02-12-19, 05:19 PM
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Correct. The battery being used will be discharged far quicker than the one being charged.
 
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Old 02-12-19, 06:07 PM
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the electrical inefficiency and friction soon take their toll!
In essence that is exactly why a perpetual motion machine is impossible to make. There will always be inefficiencies and entropy loss. The closest to a perpetual motion (energy) machine would be the sun (star or nuclear reaction) and even those eventually die out.
 
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Old 02-12-19, 06:48 PM
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I am summarizing when I give you this scenario. You need to rig this up just like a car.

Battery starts the motor
Motor turns an alternator
alternator charges the battery & provides electricity for the motor.

Again, there's more to it than this but is the basic operation/process.
 
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Old 02-12-19, 07:38 PM
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I think you are all mis understanding. He is not asking about a perpetual motion machine. I think he is talking about two batteries.
He wants to know why the battery to be charged does not try to make the charging motor run instead of charging the battery.
 
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Old 02-12-19, 07:56 PM
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Somehow, I cant get my mind wrapped around a motor charging a battery but I am honestly, quite sure it can be done. And I am not being rude with my response, I am just trying to help.

I understand he is working with two batteries, but they are/will be wired differently from different components. Again, I am not being rude but, its kinda like asking why the lights don't come on when you start the toaster. Its wired differently. Its not wired the same. There are different components... & is directing the electricity to those different components via different routes to accomplish the end result (either to run the motor or charge the battery).

Simply put, you can't just connect one end of a wire to the motor & the other end to the battery & expect it to just know what you want out of it. The project has to be wired correctly, with the correct components, to reach the end result/goal.

Battery #1 has to be connected to do what you want to achieve... start/run the motor. Battery #2 has to be connected to do what you want to achieve.... charge the battery.
 
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Old 02-12-19, 08:02 PM
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We are talking DC here. Basically a DC motor and a DC generator are constructed the same. Crank a DC motor and it acts as a generator. Feed DC to it it acts a motor.
 
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Old 02-12-19, 09:22 PM
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Battery #1 has to be connected to do what you want to achieve... start/run the motor. Battery #2 has to be connected to do what you want to achieve.... charge the battery.
And I think that is exactly what he is asking. What goes in between to make it a generator?
 
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Old 02-13-19, 06:00 AM
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To me it sounds more like a school science fair project and not a perpetual machine believer.
 
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Old 02-13-19, 07:05 AM
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Simply turning the motor shaft by external means causes the motor to become a generator. (Some motors require a momentary supply of electricity as if to treat them really as motors in order to get them started generating electricity.)

Nothing useful happens if you electrically connect a "generator" to power a "motor" and the "motor" is mechanically connected to turn the "generator" A stalemate will occur as to which device is the "motor" and which device is the "generator".

At any rate the "generator" will not put out enough electrical power for the "motor" to provide enough mechanical power to turn the "generator" to produce said electrical power.

Incidentally, the greater the load put on the "generator" say to light a lamp bulb or charge a battery, the more difficult it will be to turn its shaft.
 

Last edited by AllanJ; 02-13-19 at 07:21 AM.
 

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