zenger Posted May 10, 2015 Report Share Posted May 10, 2015 Hello all - I'm a newbie to this forum. I have a 1975 280Z, alternator is only charging 11.3 volts aat 1000 rpm, idle speed, but produces 14 volts at 2000 rpm, is it the alternator, or voltage regulator? Please help. Quote Link to comment
MicroMachinery Posted May 10, 2015 Report Share Posted May 10, 2015 Check your belt tightness. Quote Link to comment
zenger Posted May 11, 2015 Author Report Share Posted May 11, 2015 It was the first thing I've checked, belt is not loose, all wires are fully connected. @1k RPM, voltage is low, but at 2k RPM, it is at 14.3 Quote Link to comment
flatcat19 Posted May 11, 2015 Report Share Posted May 11, 2015 Have you replaced the alternator recently? Too big of a pulley? Quote Link to comment
datzenmike Posted May 11, 2015 Report Share Posted May 11, 2015 Probably bad diode(s) Quote Link to comment
Dolomite Posted May 11, 2015 Report Share Posted May 11, 2015 I've had two datsun alternators do this. You could rev the piss out of the engine and they'd charge at idle for a while but that trick wouldn't work very long. Sounds like replacement is in the near future. Quote Link to comment
banzai510(hainz) Posted May 11, 2015 Report Share Posted May 11, 2015 is everything off at idle or you have the heat /lights ON? I would call it ok. But then rev to 2k then put everything ON and if then it loads down than maybe look at low alt output. the volt reg seems to be working fine Quote Link to comment
banzai510(hainz) Posted May 11, 2015 Report Share Posted May 11, 2015 Contack Icehouse on here he said there is a C clip splice that does this alot on wagons where the rear light go bad. Its near the fuse box area I think but Ichouse(jeff Hino knows wagons) Quote Link to comment
Tolkmod Posted July 17, 2015 Report Share Posted July 17, 2015 I have this exact issue with my 74` B210... Its a fairly new rebuild on the alt, done just last year bu the PO, (have the recept) earlier when i noticed the positive wire had broken off of its terminal i also noticed that the white clip that plugs into the back of the alt was a little loose. When i pushed it in to get a good connection it sparked slightly. I traced the wire to what looks like the voltage regulator mounted by my coil. So putting things together im assuming that my regulator is shot now? Quote Link to comment
DanielC Posted July 17, 2015 Report Share Posted July 17, 2015 Another common cause of not charging at low RPM is the brushes in the alternator worn out. At low RPM, the rotor in the alternator needs a full 12 volts to charge. As the RPM goes up, the voltage regulator put a resistor in series with the rotor, to cut back on the current, and this regulates the voltage. If the alternator is turning really fast, the voltage regulator may disconnect the alternator rotor completely. Quote Link to comment
Tolkmod Posted July 18, 2015 Report Share Posted July 18, 2015 well, while i save up for a higher amp alt (and from all signs i'm gonna need one anyways) I ordered a new regulator. was only $20-ish. I'll update to let ya'll know if that was the issue. Quote Link to comment
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