# Battery that will run a dc motor

1. Mar 25, 2010

### Mujahid

hi i am new to this forum. i want to use a battery that will run a dc motor, dc motor will run three phase ac generator through mechanical coupling and the three phase ac generator will produce out put, now two phases of the ac generator will b utlilized by the load and 1 phase will recharge the battery. my question is wheather its possible or not?

2. Mar 25, 2010

### Naty1

Re: hybrid power

yes is possible. But you will need to separately and independently recharge the battery periodically since friction and electrical losses cannot be overcome.
In other words its impractical.

Try here for practical insights: http://en.wikipedia.org/wiki/Hybrid_car

3. Mar 25, 2010

### Mujahid

Re: hybrid power

sir you mean its theoratically possible but practically impossible?

4. Mar 25, 2010

### Naty1

Re: hybrid power

no I mean it can be done but accomplishes nothing....except temporarily until the battery runs down....trying to recharge the battery from the output consumes more energy than it produces....

5. Mar 25, 2010

### Staff: Mentor

Re: hybrid power

Even theoretically with 100% efficiency and no losses anywhere in the system the 1 phase used for recharging cannot recharge the battery faster than it is being drained if there is a load on the other 2 phases.

It is certainly possible to build the device you describe, but it won't recharge the battery as fast as it is drained.

6. Mar 25, 2010

### gmax137

Re: problem

No, it is not possible. Violates conservation of energy.

7. Mar 25, 2010

### Mujahid

Re: problem

how sir?

8. Mar 25, 2010

### Mujahid

Re: hybrid power

is there any alternative?

9. Mar 25, 2010

### stewartcs

Re: problem

If you use part of the converted a/c power to charge the battery there will still be a net loss of energy (due to irreversibilities in the conversion process). So strictly speaking you can "charge" the battery, but you can't fully recharge it such that it violates the conservation of energy.

In other words you cannot create a perpetual motion machine. The battery will eventually drain completely.

CS

10. Mar 25, 2010

### Staff: Mentor

Re: hybrid power

Yes, charge it with an external power source.

11. Mar 25, 2010

### stewartcs

Re: hybrid power

This is the third post of this exact topic by the same user...

Do not multipost...

CS

12. Mar 25, 2010

### Mujahid

Re: hybrid power

can we eliminate all the losses?

13. Mar 25, 2010

### Mujahid

Re: problem

is there any research on practical perpetual motion machine?

14. Mar 25, 2010

### Staff: Mentor

Re: problem

We do not discuss perpetual motion machines here on the PF because it is a waste of time. Please re-read the Rules link at the top of the page.