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Alternator diode

D

David G

Well-known Member
I am looking for a diode to energize my new alternator. What part number should I look for, and who carries them?

Thanks,
 
Are you meaning the diode that is put in one of the regulator wire on a three wire Delco 10SI alternator? If so any 2 amp 1000 PIV diode available at Radio Shack will do. If this is on a Delco 10SI, the diode does not energize the alternator. The diode, when installed correctly, keeps the regulator from back feeding the ignition system allowing you to stop the engine when you turn the ignition switch off.

Kent
 
3 amp 100PIV diode will be fine, radio shack or other electronics store will have several.
1N5408 is one number that works. Jim
 
Its easier to just stick in a 10 to 20 ohm resistor or an incandescent idiot light which provides some degree of current limiting PLUS the light will give some indication of charging. Of course a diode will work (many people use them, I have) but doesnt give the charge indication or current limiting. If a diode a 3 to 5 amp and 100 volts ought to do the trick.

John T
 
(quoted from post at 17:20:10 09/04/11) Are you meaning the diode that is put in one of the regulator wire on a three wire Delco 10SI alternator? If so any 2 amp 1000 PIV diode available at Radio Shack will do. If this is on a Delco 10SI, the diode does not energize the alternator. The diode, when installed correctly, keeps the regulator from back feeding the ignition system allowing you to stop the engine when you turn the ignition switch off.

Kent
Click to expand...

Actually on the original style three wire 10SI alternator the diode will be used to provide initial voltage through the voltage regulator and then to the rotor windings. Once the alternator starts to charge the diode trio provides the voltage the the rotor though the regulator and the external voltage is no longer required for the alternator to continue to charge.
 
I like to use a resistor/light instead of a diode too. If the key is left on with the engine not running,the alternator will drain the battery faster if using a diode.
 
"If this is on a Delco 10SI, the diode does not energize the alternator."

REALLY? (Well I guess I learn something every day, even Sunday!)

"The diode, when installed correctly, keeps the regulator from back feeding the ignition system"

So, you are saying, then, that the regulator MAKES voltage/current??????????????????????????????

(I'll help you out a little... the power than can backfeed and keep the the engine from shutting down comes from the STATOR, and is rectified by the diode trio.)
 
If winding Resistance is approximated as 0 ohms than wattage for 20 ohm resistor:

P=V^2/R
Watts =14*14/20
10 watt is enough
 
Back many years ago the first one i did I used a push button...Pushed it one time when motor was running...Always try to use light now.....
 
AND when a Diode is installed correctly in the wire normally colored white in the regulator plug, the diode blocked the voltage generated in the alternator which appears on the regulator terminal from causing the engine NOT to shut off when the ignition key is turned off. I installed a Delco 10SI on a old Oliver 88 diesel. The was I energized the alternator was with a HOBBS oil pressure switch. I did not need to install a diode in this system because the engine shutdown was a mechanical wire.

Kent
 
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