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-   -   Stupid question, How does a starter work? (https://www.rx7club.com/general-rotary-tech-support-11/stupid-question-how-does-starter-work-601527/)

DelSlow 11-30-06 11:15 PM

Stupid question, How does a starter work?
 
I know how it engauges and disengauges and the general workings of it. I was just wondering how does it draw so much current from the battery? Does it have some kind of transformer or something? Size/number of windings?

Someone who knows something about electronics explain this to me if you could...

Einstein 12-07-06 11:14 PM

Basically two pieces - solenoid and the actually starter motor itself. The starter has a massive amount of windings to be able to turn over the engine. Without the solenoid though, all it does is spin in place. Now to make the starter 'engage' with the flywheel/flexplate, it must be pushed out by the solenoid.

So if the solenoid goes bad, all you get is a whirring noise from underneath.
If the motor goes bad, then you get things like slow starting or just a click then nothing.

The starter draws so much amperage because it has very little resistance. The formula for calculating is E = I x R. E = Voltage, I = Current, and R = Resistance. Thus if a starter draws 240 amps and you have a 12v battery then you can get the resistance of the starter motor to be .2 ohms.

Just in case the term solenoid is confusing - if you take an iron core and wrap it in wire, then put voltage through the wire, you make an electromagnet. Well if you just have the wire coiled and have the core partially inserted into the coil, then you power up the coil, the core will move into the coil. Add a spring to return the core to its original position and you have a solenoid. To a solenoid you can attach things to do work (like a starter) or modify the design a little to open passages (injectors and such).

*Edit* And there's no such thing as a stupid question. My 'stupid' questions are the ones that usually stop me from doing something that is stupid or they save me a lot of work.


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