Hello,
This is the alternator i built a few weeks ago, but today i had the chance to make some tests and i decided to share the results with you.
I made some mistakes in design, but this is a small alternator and i made it to gather some experience, before building a multi KW alternator. The alternator is made from Plexiglas, i should have used steel plates at least for rotor magnets instead of Plexiglas. I'm attaching photos.
So i have 6 coils, 2.5in x 0.5 in (0.0525 wire, 140 turns 10 x 14)
My magnets are N52 Disk magnets Diameter 1 1/8 x 3/8 thick (16 magnets, 8 on each rotor) 45Lb pull force. They may not be N52 in fact.
Distance between stator and rotor about 1/16 on each side.
For testing i'm using a DC motor that is 1100 RPM @ 30V
On motor side i'm measuring V on motor and Consumption in Watt
On alternator side i'm applying different loads (50 watt resistors, 4Ω, 6Ω, 8Ω, 10Ω, 12Ω, 15Ω, 17Ω, 19Ω, 21Ω, 23Ω, 25Ω, 27Ω) and measuring watts and Volts with a DC watt meter
i used different power supplies to power the motor, 11.1V, 12.5V, 14.6V, 19.1V, 24.5V.
My best efficiency is 46.02% seems to be on a 21-23Ω load at 19.1V. Of course we need to take into account here the efficiency of the DC motor which could be ~80% if not less, it's a 30 years old motor. So the actual alternator efficiency could be ~65%-75%. Am i correct?
Well i was expecting i will squeeze more power from this alternator, but the maximum was ~100Watt @ 30.36% efficiency which is bad.
I'm planning to rebuild the alternator, same magnets, i might replace the coils if needed, steel plates on rotor...
Could you please suggest what other changes i should make to be able to squeeze more power @ higher efficiency while using same magnets?
What is the best
