I have a 300U with a used single wire alternator. The previous owner was in the process of installing and wiring the alternator. I have installed a new amp gauge and completed the wiring. Upon startup and the alternator charging pegged the amp gauge at idle it continues to charge at more than 10 amps. My first thought was the battery is low but by now charging should be tampering off. Could the internal regulator be bad?
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Janicholson
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yes. If you measure the voltage at 1/2 throttle with a charged battery, it should be 14.2 to 14.6 volts. 15 if cold. If more than 15 it will destroy the battery if operated for hours. Jim
That "single wire" alternator output wires up to the Load (NOT battery/starter) side of the ammeter, the same terminal that feeds battery voltage to loads such as lights and ignition etc. The other Supply side of the ammeter gets to the batterys hot ungrounded post, often by a wire down to where the big battery cable attaches to the start switch/solenoid. Often then theres ONLY ONE wire on the ammeters Supply side (to battery/starter) and maybe two (Alternator and wire to light/ign switch) on the Load side....
If all is wired right yet it drastically continiues to overcharge (keeps battery at say 15 volts all the time) Id say the Voltage Regulator is bad and that will cook the battery...
On the 10SI 3 wire units that one small terminal was used to sense battery voltage, maybe the alternator isnt sensing true battery voltage
John T
If all is wired right yet it drastically continiues to overcharge (keeps battery at say 15 volts all the time) Id say the Voltage Regulator is bad and that will cook the battery...
On the 10SI 3 wire units that one small terminal was used to sense battery voltage, maybe the alternator isnt sensing true battery voltage
John T
Janicholson
Well-known Member
That is correct.
A three wire is very easy, has no parasitic draw when parked, and starts charging at idle speeds. The one wire uses a modified voltage regulator that remains on all the time. Bob M wiring diagrams has the procedure for setting it up. If you become irritable with the one wire. Jim
A three wire is very easy, has no parasitic draw when parked, and starts charging at idle speeds. The one wire uses a modified voltage regulator that remains on all the time. Bob M wiring diagrams has the procedure for setting it up. If you become irritable with the one wire. Jim
before you get to in depth with it ,try changing the battery to one that's known to be good,btdt with a ford 351 cleveland build for racing battery would spin it like a top ,alternator wouldn't charge less than 20 amps after several tests and plenty of trail and error attempts to solve the problem it turned out to be the battery, not common but it happens
Anonymous-0
Well-known Member
You don't say what the range of your ammeter is. If you have a 30 amp or less gauge, you can expect it to peg after start up. I use a 60 amp. Depending on the output rating of the alternator, it may still peg initially, but should soon tapper back. Alternators have a much higher output the the old generator. The smaller common Delcos are about 40 amps.
If voltage on a fully charged battery exceeds 15 volts, the regulator is probably bad.
If voltage on a fully charged battery exceeds 15 volts, the regulator is probably bad.
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