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Hitachi alternator/voltage regulator help

P

PoppinJohn720

Member
Guys, I'm trying to help my father in law figure out a current draw problem in his 54 model Cub which has been set up with a small Hitachi alternator and what looks like an old Ford four terminal voltage regulator. This unit charges the battery in the 13.2-14.6 volt range everytime I've tested it with a DVOM. When the engine is shut down the field coil inside the VR stays powered up causing a 0.3A draw on the battery which over a day or two in cold temps causes the battery voltage to drop to the point it has to be jump started. I think the problem is due to improper VR/ Alternator connections. I have searched the net all over trying to find a correct wiring schematic for the VR but I come up out of luck. I hope you gentlemen can bail me out. Thanks!
 
Yes very likely that the VR is not matched to the alternator. I have found one easy way to figure things like that out if your hopefully friendly auto part store and there books. Sorry the books I have right here on the desk do not give me info you want.
 
Put a 3 amp diode in the wire going to the brushes in the alt field. (wire with the .3 amps draw) the diode is available at Radio Shack. 1N5408 is a good number.
Install it with the band on the diode close to the alternator. If the draw is not in the regulator, but in the power lead (big wire) this solution will not work. Jim
 
I think those regulators used battery power to feed the alt. Put a switch in that wire to shut it off when you stop the engine, or wire it so it shuts off with the engine if it is battery ign.
 
Jim I have found the radio shack part #276-1661 to be the best diode you can buy for alternator jobs. Extra heavy so it can take higher peak voltage and cost you $2.50 for a pack of 4
 
Here is a Hitachi alternator that I put on our SW6. CharlieU makes the brackets. Stock belt also, can't see any of it with hood on.
IMGP1243_zps3d9aa311.jpg

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IMGP1242_zps495ddf4e.jpg
 
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