Exciting field coil on homemade powerplant 12V

 

Made a power source with lawnmower engine and delco alternator w/
internal reg.  Didn't want to mount a full sized battery.  How much
power is needed to excite the field?  I have the field wire connected
to the + on the alt., so I just need to give it power to start
producing.  Maybe a small UPS battery on a momentary switch?

 

kenroughty wrote:

Not much needed, saw an article several years back where they used a
small battery saver solar panel to provide the excite, then
boot-strapped from that.

 



You can probably flash the field of such a small unit with a couple of
D-cell batteries.  Start it up, and if there is no output apply the D-cell
batteries to the + on the alt for just a couple of seconds.  It should
'bootstrap' itself up to the regulator setpoint in just seconds.

daestrom

 

If you use a Harley Davison permanent magnet alternator, you dont need
to waste 40 watts running the field coil. Interested in efficiecy or
just low cost?

 

kenroughty wrote:

You need to connect a battery of any size but voltage has to be equal to
ALTERNATOR output. With internal regulator the fields get more energized
as external voltage at battery drops. Battery plus to alternator
terminal and ground to alternator frame.

--
James Storm
aka Stormy Weather
jstorm@ptd.net