I have often posted the info below about how important it is to use a lamp, resistor, or diode in the circuit to the #1 "excite" terminal on a Delco alternator.
It usually gets pooh-poohed because someone has set theirs up using (for example) a direct connection to the ACCY terminal on the ignition switch and it has worked for years.
Yesterday, I worked on a tractor set up that way. A wire terminal cracked and broke, interrupting the charging circuit between the alternator and battery, and the little diode trio tried to step in and take up the slack by charging the battery through the direct-connected "excite" circuit with the results being shown in the bottom photo.
<img src = "http://www.gondtc.com/~blweltin/Bob/DelcoSIA1A.gif">
<img src = "http://www.gondtc.com/~blweltin/Bob/DelcoSIB1A.gif">
<img src = "http://i.imgur.com/PmUt90E.jpg">
Good trio on left, burnt trio on right.
It usually gets pooh-poohed because someone has set theirs up using (for example) a direct connection to the ACCY terminal on the ignition switch and it has worked for years.
Yesterday, I worked on a tractor set up that way. A wire terminal cracked and broke, interrupting the charging circuit between the alternator and battery, and the little diode trio tried to step in and take up the slack by charging the battery through the direct-connected "excite" circuit with the results being shown in the bottom photo.
<img src = "http://www.gondtc.com/~blweltin/Bob/DelcoSIA1A.gif">
<img src = "http://www.gondtc.com/~blweltin/Bob/DelcoSIB1A.gif">
<img src = "http://i.imgur.com/PmUt90E.jpg">
Good trio on left, burnt trio on right.