Both alternators and generators have regulators. The regulator controls for output voltage AND for output current. It will limit voltage if at max current - as current drops (battery is charging) then regulator will increase voltage to whatever it is set for.
The ammeter in automotive common setups measures ONLY the current in or out of the battery - that is why it is zero at center and + at one end and - at the other extreme end. You could have a one megawatt alternator in truck
BUT if the battery only wants 30 amps that is all the ammmeter will read.
IF mine I would have all wiring and components between battery and alternator (or generator) sized for full current of the unit plus 10% AND for the voltage.
I am just an industrial and power plant electrician. ALL alternators and generators I worked with had at MINIMUM a voltmeter and an ammeter. You need both to know the full story.
The submarine battery I worked with had a meter +5,000 to - 5,000 amp.
IF my truck I would have a battery current charge / discharge meter on dash. This would be a shunt unit to minimize wire length and voltage drop. In the engine house I would have voltmeter and ammeter for alternator (generator?) output.
Dan Bentler
Last edited by leitmotif; 11/30/2010 4:12 AM.
