Alternator needs battery power to generate power?

[Yendor]

Thanx mate..but..

Alternator stator winding need the field winding(magnet) to generate electricity out of the stator winding.
Then without a battery to initially turn the field winding into a magnet it apparently won't work?
But, once the stator winding started generating electricity, it can feedback to the field winding and feed each other?

So, it it essential to have a battery connected to the field winding, at least for a fraction of a second to generate electricity out of the stator winding?

Does it work in theory?! I mean like chicken or the egg first sort of situation(which obviously I don't have to understand, but would love to ).
Is possible by wiring up an alternator to self excite by connecting the trigger wire to B+?!!
If I understood you correctly above, it's possible, provided I work out the proper RPM spot for that by experimenting?

Are you talking without a battery fitted?. Without a battery fitted I would doubt an alternator will start charging.

I understand that without a battery, alternator B+ output voltage won't be smooth(battery function as a capacitor to smooth the alternator's pulsed DC output?).
So, if I'm to use an inverter, it would be a good idea to make alternator's output is smooth by connecting a battery to B+?!!
And that would also apply to many 12V appliances as well.

The only issue with using a decent size battery in the unit is that it would make it heavy. But, of course, the battery doesn't need
to be attached/fitted to the generator.

Without a battery fitted the regulator will have a hard time controlling the voltage. Depending on the load of accessories voltage could rise up to 19 volts

[dom14]

You could use a small pony alternator that uses permanent magnets to give an initial start up. I have tried running alternators on a bench test, but I had to flash start the field.

Ok, cool.
If i understood you correctly, it's possible to "self excite" an alternator in theory and practical,

but I still need to give the initial "flash" to the field coil via a battery(unless the field coil is a permanent magnet setup)!?

[dom14]

Are you talking without a battery fitted?. Without a battery fitted I would doubt an alternator will start charging.

Yes, without battery fitted modern alternator won't be able to generate any power. Am I right?
At least we need a battery connected to the field coil for a fraction of a second to generate any power via the stator coil?

Without a battery fitted the regulator will have a hard time controlling the voltage. Depending on the load of accessories voltage could rise up to 19 volts

Yes, I understand. You explained that pretty well in previous post.

[dom14]

Thanx mate.

I think I understand it now.

Battery is needed for at least three purposes

1)To "flash" the field coil initially, so the stator coil can generate electricity.

2)To smooth out the pulsed DC output from alternator B+ as it would in a conventional bridge rectifier equipped AC/DC conversion circuit with a capacitor.(battery = capacitor in this case).

3)Regulator would need the battery to regulate the output voltage of the B+

Am I right?

[Yendor]

Yes, without battery fitted modern alternator won't be able to generate any power. Am I right?
At least we need a battery connected to the field coil for a fraction of a second to generate any power via the stator coil?

Without a battery positive connected to the B+ terminal of the alternator and the negative connected to the housing of the alternator it's very unlikely to start charging.

It is possible with the battery connect as above and the warning light circuit (or trigger/field as per the diagram you posted) not connected for the alternator to start charging. But you would need to find the sweet spot in the RPM.

[Yendor]

Thanx mate.

I think I understand it now.

Battery is needed for at least three purposes

1)To "flash" the field coil initially, so the stator coil can generate electricity.

2)To smooth out the pulsed DC output from alternator B+ as it would in a conventional bridge rectifier equipped AC/DC conversion circuit with a capacitor.(battery = capacitor in this case).

3)Regulator would need the battery to regulate the output voltage of the B+

Am I right?

Yeah I can live with that.

[dom14]

Without a battery positive connected to the B+ terminal of the alternator and the negative connected to the housing of the alternator it's very unlikely to start charging.

It is possible with the battery connect as above and the warning light circuit (or trigger/field as per the diagram you posted) not connected for the alternator to start charging. But you would need to find the sweet spot in the RPM.

Yes, if I learnt it correctly from your posts, the wiring of my proposed home made generator has to be almost like the wiring in the wiring diagram to make it useful, including having a battery.

So, "self excitation" of modern alternators is NOT possible without the initial "flash" of electricity into the trigger/field/exciter wire.
After that, self excitation can continue, provided I get the correct RPM right for that.

[Yendor]

Yes, if I learnt it correctly from your posts, the wiring of my proposed home made generator has to be almost like the wiring in the wiring diagram to make it useful, including having a battery.

Yes except just wire the sense wire to the B+ on the back of the alternator.

So, "self excitation" of modern alternators is NOT possible without the initial "flash" of electricity into the trigger/field/exciter wire.
After that, self excitation can continue, provided I get the correct RPM right for that.

There's no guarantee that without the warning light circuit connected that the alternator will start charging every time. But normally you can find a spot in a certain rev range and it will.

[GeeYou8]

Maybe the project needs to be changed to a petrol powered battery charger?
My 2 cents worth is that there will always be some residual magnetism in the rotor for self excitation, you could add a couple of little button magnets to the rotor, would affect your regulation a bit. Still need a battery to smooth things out.
Graham

[dom14]

Maybe the project needs to be changed to a petrol powered battery charger?
My 2 cents worth is that there will always be some residual magnetism in the rotor for self excitation, you could add a couple of little button magnets to the rotor, would affect your regulation a bit. Still need a battery to smooth things out.
Graham

Hey Graham,
Thanx for the tip mate.
Actually this was a little garage project I started last year, then abandoned for some reason.
I think the potential noise put me off.
Now, I realize it's not that hard to come up with a good backyard muffler to reduce the noise.
Cheers
Dom