Running an alternator

Lew Silverman · 09-20-2017, 04:51 PM

All else being equal, an alternator is going to output somewhere between 13.7 and 14.2 volts on a 12 volt system, normally with a load and at idle. A well charged (100%) battery is right around 12.7 volts, so you get at least a 1 volt "boost" with the alternator running properly. It would be interesting to see what the effect of the load of a alternator would have on a vehicle with a fully-charged vs. under-charged battery. Could it be done on a dyno? From personal experience I've discovered that a one-wire unit needs to "spool-up" before it begins to charge, so it's either a small crank pulley or large one on the alternator, not BOTH!!

09-20-2017, 04:51 PM	#17
Lew Silverman VIP Member Join Date: Mar 2010 Location: Newport News, VA Posts: 1,435 Likes: 371 Liked 129 Times in 59 Posts	Re: Running an alternator All else being equal, an alternator is going to output somewhere between 13.7 and 14.2 volts on a 12 volt system, normally with a load and at idle. A well charged (100%) battery is right around 12.7 volts, so you get at least a 1 volt "boost" with the alternator running properly. It would be interesting to see what the effect of the load of a alternator would have on a vehicle with a fully-charged vs. under-charged battery. Could it be done on a dyno? From personal experience I've discovered that a one-wire unit needs to "spool-up" before it begins to charge, so it's either a small crank pulley or large one on the alternator, not BOTH!! __________________ Lew Silverman #2070 "The Wagon Master" N/SA