volroom
Race Dog
I've attached a voltmeter to my battery, so I could keep an eye on the voltage with my 'Ultra-disappointing-battery'. I've wondered about this for a while...when I start the bike, the voltmeter reading is around 12.5V (with a good battery). Then when I blip the throttle, it sounds like the engine is working harder, the revs drop slightly at idle, and the voltmeter reading shoots up to 14V plus. Speaking to LeCap, it seems that the alternator is not energising the rotor (our alternators are like car alternators with the rotor coil acting like an electromagnet - not permanent magnet) until you blip the throttle. I tested this, and it's true - the voltage on the battery starts dropping if you don't blip the throttle, meaning that the battery is not being charged..only discharged. I'm wondering if there's something wrong with my vark, or is the common? Also, what can be the reason for this, maybe it's starts easier if the alternator is not working initially (this is explained by Lenz's law - basically, the magnetic field interaction between rotor and stator is such that there is opposition - literally a force that opposes the rotor from spinning - I think our alternator can easily sap around 1kW from engine power - maybe this is why the battery does not push current through the rotor when you start the motor - so idling is easier - spinning the rotor itself does not require a lot of energy if magnetic fields don't interact).
