Pedal generator alternatives

I tried to hook up my bike first to alternator because alternator has built-in voltage regulator. When turning rotor at different speeds, regulator keeps output charging voltage at optimal ca 14V range. Unfortunately my alternator seemed to have some issues and i went on exploring other possibilities.

Basically every motor can be turned into generator by spinning it. I took one QVALDA cordless drill which has 18V permanent motor inside and including gearing produces 15Nm of torque. Drill head seemed like ideal piece to be driven by tyre and actually it worked when applying moderate pressure. Open circuit voltage was easily 20V when pedaling at normal speed. Problems arised when i attached some load, tyre grip just was not enough. What amazed me was that when turning drill head half a turn with fingers it generated already 2-3A amps of current!

Alternator consists of single field pole at the rotor that creates moving magnetic field. Actually alternator initially generates 3-phase alternating current that is later rectified. What regulator does is changing current in field pole so that in turn changes output voltage from stators windings. As i tested alternator by often connecting and disconnecting battery then it could be this fired my regulator as this creates high spikes in voltage.

Anyway i prefer using alternator above other motors. This is because alternator is almost complete battery charging solution, its capable of sourcing a lot of current and its cheap to buy from junk yards.