The Unofficial Mamod and Other Steam Forum

Wallace · Posted: Sat Nov 25, 2006 1:17 am Post subject:

That light flare is normal to a certain degree.
From idle to about 2000rpm they will flare.

If they get brighter from 2000rpm up, and keep getting brighter, the alternator might need a rebuild, amongst other things

My mate had a car that the lights would be barely working, and would get overbright at 5000rpm.

Was funny at night changing gears.

Funny until we were driving and his battery exploded.

I thought a grenade had gone off

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Mamodman123 · Posted: Sat Nov 25, 2006 1:21 am Post subject:

niluht · Newbie Joined: 23 Nov 2006 Posts: 53 Location: B.C. Canada

I too was wondering if a small electric motor would work as a generator to light a small bulb.

Hooked a motor to a volt meter, spun the shaft between my thumb and finger, and got a couple of volts! I thought I had it.

Absolutely nothing with a flashlight (torch in the UK ?) bulb.

Next I hooked the wires of a second motor to the first, and spun the shaft in an electric drill. The second motor actually spun

Thus I knew there was some voltage and current produced, but not in the right quantities or proportions to light the bulb

The most perplexing thing though, was what I noticed about the motor. With nothing attached to the motor, the shaft would spin easily with a twist of my fingers- free wheeling for many revolutions before stopping. Same when the two motors were connected to each other. However, when the motor was connected to the light bulb, the shaft would not free wheel at all. It was still very easy to spin, but it absolutely would not coast.

Clearly there is a significant difference between a bulb and a motor as electrical loads. I think it has to do with the bulb being a resistive load, and the motor something else. Not too up on electric circuits and such, just found it interesting.

Cheers,
Jeff