Owen Posted June 17, 2002 Share Posted June 17, 2002 I know these things need to hit a certain RPM before they start charging, but I read that this RPM only has to be hit once to hit the switch and then charging will begin. Is this true? Or does the alternator have to run continuously at the cut-in RPM? Thanks. Owen Quote Link to comment Share on other sites More sharing options...
Tim240z Posted June 17, 2002 Share Posted June 17, 2002 I have a 1 wire on the truck. It charges as soon a I start it, but I do have to give it a couple of blips when its cold to fire it. I'm sure that once it's excited enough it will continue to charge. Tim Quote Link to comment Share on other sites More sharing options...
blueovalz Posted June 17, 2002 Share Posted June 17, 2002 Once the alternator "turns on" the charge will continue even below the "turn on" speed. Usually, the higher the capacity of the alternator, the higher the "turn on" rpm. Quote Link to comment Share on other sites More sharing options...
Owen Posted June 17, 2002 Author Share Posted June 17, 2002 Thanks! That's what I needed to know. My battery is still draining though...faster than it charges.... Owen Quote Link to comment Share on other sites More sharing options...
Tim240z Posted June 17, 2002 Share Posted June 17, 2002 What voltage is the alt charging at? Is the battery any good? Tim Quote Link to comment Share on other sites More sharing options...
blueovalz Posted June 17, 2002 Share Posted June 17, 2002 Are you sure it's charging at all? Quote Link to comment Share on other sites More sharing options...
spotfitz Posted June 17, 2002 Share Posted June 17, 2002 I just purchased a 100amp 1 wire alternator and it doesn't have a turn on rpm, which probably goes back to the amperage being so low. When I asked for the excite rpm they just looked at me funny because it stated 55 amp at idle, which I guess all depends on the idle speed of say 750? As blueovalz suggested, the higher the amperage the higher the excite rpm. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted June 17, 2002 Share Posted June 17, 2002 I'm making an educated guess here but I think the "turn on" speed of something that large is going to be around 1300-1500 rpm. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted June 17, 2002 Share Posted June 17, 2002 Yeah thats been my experience recently Terry, mine at about 1500 on the tach I can watch the voltmeter showing charging as the volts start creapin up. I've noticed on the meter your voltage goes up proportionally to RPM, but it will still charge once it goes back to idle just not at a horrific rate. Regards, Lone Quote Link to comment Share on other sites More sharing options...
Owen Posted June 17, 2002 Author Share Posted June 17, 2002 Tim, The alt WAS charging at a pretty high rate, but that crank pulley I got is the same size as the alt pulley, 1:1. Terry, No, it's not charging at all. If it is, it's not as fast as the components that drain the batt. I've read all over the net that cut-in is around 1200-1500 rpm. They make ones with lower rpms but I'll do some more observing to see if it's gonna be a problem. Owen Quote Link to comment Share on other sites More sharing options...
blueovalz Posted June 18, 2002 Share Posted June 18, 2002 If the issue is spinning speed of the alternator, I would also investigate a smaller pulley for it. I went to an alternator rebuild shop (armature rebuilder) and he had a whole box of used pulleys to choose from. I finally chose a 2:1 ratio, which is still low as I've seen many in the 3 and 4:1 ratios on stock motors. If you do have a 1:1 ratio, then that's SLOOOOOOOOWWWWWWWW. Quote Link to comment Share on other sites More sharing options...
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