Vehicle starting system

For one thing, an alternator makes AC. A starter motor needs an energy source from somewhere, and the battery, which is a DC device, is where it gets it from.

Next!

But actually in vehicle both alternator & starter motor presents. Starter motor starts the engine & then alternator starts charging the battery.

Can alternator be used as starter motor?

Please refer to reply #1.

And the lack of available torque..and the fact that the drivebelt couldn't handle the torque even if you did have it....

But supposing you could lift all the valves at once to make it easy to turn the engine...then maybe if you got it to spin up to say 5000rpm then let the valves come back in as you dissengage the alternator to stop the belt snapping...and...sorry getting silly now...

Some small marine outboard motors use generators as starter motors, so it can be done, but alternators aren't suitable for that, as they require alternating current to run as a motor. In addition to that, most automotive alternators have built-in diodes to rectify the AC, and with those present, you can't get AC to flow backwards through a diode anyway.

Hello

You May answer your own question by determining how much amperage a starter draws without burning up.

The general rule of thumb is one amp per cubic inch of engine. Alternators will not survive.

Sorry

TeamSarge