# Car batts

1. Oct 14, 2011

### 94yashwanth

hey guys can anyone pls say how much current in amps does a ordinary car battery of 12v generates?? pls......

2. Oct 15, 2011

### Danger

Generally, the measurement used is "cold cranking amps", which is the bottom line when it comes to starting the vehicle. In the old days, that used to be somewhere around 350. I had to mount a 690 amp tractor battery in the trunk of my Roadrunner, in parallel with the standard unit, in order to start the engine in winter. Nowadays, though, you can get over 1,000 in a standard size case.

3. Oct 15, 2011

### 94yashwanth

thanx dude...and how can we connect a car battery to a motor?? and how to increase the RPM of a motor?? any idea!

4. Oct 15, 2011

### Drakkith

Staff Emeritus
Can you elaborate one what you are trying to do exactly? It sounds like you want to pump a lot of amps through an electric motor, which is probably a very bad idea if you don't really know what you are doing.

5. Oct 15, 2011

### rcgldr

Assuming it's a "12 volt" (actually 12.8 volts or more if something is charging the battery at the same time) volt brushed DC motor, the current draw will be related to the load on the motor, with max current occuring on a stalled (not rotating) motor. As long as the battery can produce enough voltage and current, the limitation is on the motor side. Most motors will burn up if under too heavy a load and/or running for too long a time.

If it's a 12 volt brushless dc motor, you'll need a controller, and both the motor and controller will limit voltage and current.

Max rpm occurs under no load. Unless you run excessive voltage into a motor, like trying to run a 9 volt motor with a 12 volt source, there shouldn't be any issues with zero or light loads on the motor.

6. Oct 16, 2011

### 94yashwanth

thanx dude...adn any idea how to make a magnetic motor!!

7. Oct 16, 2011

### Danger

:uhh:
All electric motors are magnetic. That's the only reason that they work.

8. Oct 16, 2011

### 94yashwanth

yeah i do knw that...i wanted to know how to make a magnetic motor generator.....

9. Oct 16, 2011

### Staff: Mentor

10. Oct 16, 2011

### DaveC426913

Isn't that an oxymoron?

A motor takes electricity and produces work. A generator has work acted upon it and produces electricity.

They are antipodal.

11. Oct 16, 2011

### Drakkith

Staff Emeritus
http://en.wikipedia.org/wiki/Motor_Generator

Converts electrical power from one form to another. We have them at work where they convert regular 60 hz AC power into 400 hz power. An electrical motor gets power from the mains and uses it to turn a generator configured to produce the 400 hz power.

12. Oct 18, 2011

### 94yashwanth

ok...and i wanted to know is using neodymium magnts or alnico magnets how to make a magnetic power generator??

13. Oct 18, 2011

### 94yashwanth

ok...and i wanted to know is using neodymium magnts or alnico magnets how to make a magnetic power generator??

14. Oct 18, 2011

### xxChrisxx

I see where this is going.
IBTL.

15. Oct 18, 2011

Troll.