I'm trying to decide if it would be possible to use a stepper motor to replace a current 12V DC brushed motor that is used to turn over a small (~149cc) gas engine for starting.

The reason why is, I would like to use the stepper motor to generate some small current when it isn't in starting mode. I can't do this with the current brushed motor setup, as that would wear out the brushes.

My idea is that using a stepper motor would give it dual purpose: starting the engine, and generating small current when the engine is rotating it.

The current brushed motor has 0.3 ohms of resistance, but I'm not sure of it's torque capacity, so I need help picking out an equivalent stepper motor. Here's a link to the current motor: GY6 150cc starter motor

If you do not think it's feasible (like if the suitable capacity stepper motor is too big or too costly). I would like other solutions as well if you have any feedback.

Thank you.

  • 1
    \$\begingroup\$ Do they have a solenoid or clutch like auto starters, or do they rotate with the motor always? I don't think a reasonable size stepper will have enough torque- starter motors are run in kind of a balls-to-the-wall mode where they'll burn out quickly if the power is left on for too many seconds. \$\endgroup\$ – Spehro Pefhany Nov 3 '14 at 3:40
  • \$\begingroup\$ Yes, the current GY6 motor is used in conjunction with a solenoid (goal is to replace the solenoid with a MOSFET if a stepper motor can't be found) \$\endgroup\$ – klcjr89 Nov 3 '14 at 3:41
  • \$\begingroup\$ I'm not up on electric cars or the regeneration techniques used in hybrids, but in the automotive (internal combustion) industry in general a separate starter and alternator are used. I suspect if your idea were an improvement it would already be in use. \$\endgroup\$ – mickeyf Nov 3 '14 at 4:02
  • \$\begingroup\$ @mickeyf actually, it's been done back in the early 1900s and is still done today, a combo unit known as a starter/generator. They were/are used on tractors and golf carts (and many other stuff). \$\endgroup\$ – klcjr89 Nov 3 '14 at 4:04
  • \$\begingroup\$ @mickeyf. It's an attractive idea and a lot of people have tried- combine starter, alternator/generator and (electronic) flywheel in one, but it's not easy. \$\endgroup\$ – Spehro Pefhany Nov 3 '14 at 4:41

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