Raymond Carbone wrote:
>The puzzle is solved. .....the alternator's voltage regulator requires a
>differential, supplied by the resistance of the warning indicator light, to
>initiate charging. Should the bulb burn out, charging would not be initiated
>and you would have no warning if you missed the fact that the light did not
>come on prior to engine start. To rectify this potential problem, I installed
>a 15 Ohm resister parallel to the bulb to supply the alternator with the
>necessary resistance.
>
>After installing the resister, I started the engine and verified the correct
>functioning of the warning indication light. Additionally, voltage
>measurements at the BATT terminal of the Alternator and at the battery @ 2K
>RPM are now 14.6V. In short, THE ALTERNATOR IS CHARGING!!!
>
>Conclusion:
>
>It is difficult to explained what went wrong, however, I think the problem was
>one of product variation within spec. If I were to guess at the issue, I
>would suggest that my warning bulb was exceptionally low on resistance and the
>alternator's regulator required a greater differential to activate. By
>breaking the wires and adding additional solder for the resistor, additional
>resistance was entered into the circuit which tipped the scales in favor of
>activation.
>
>
>
Raymond,
Its great that you could solve your problem with the alternator. The
list serves a great purpose in resolving technical issues such as yours.
I am converting to a Delco 12 SI self exciting internally regulated
alternator for my Jag MK VII so I find all you have gone through very
informative. It sounds like a good idea to install the resistor in
parallel with the warning light and I will do the same.
I take a different view than you with the reason that the charging
system is now working on your car. When you installed the resistor in
parallel with the bulb you actually provided an additional path for
current flow. The combined current flow through the warning light and
the parallel resistor was great enough to activate the alternator field
coil so it could begin generating.
Are you able to measure the resistance of the warning lamp with a meter?
It looks like I may be able to use the existing "ignition lamp" which is
connected to the "D" terminal of the control box but am not totally
convinced. I may need to rewire something.
Alan Schultz
67HBJ8 (With Lucas Generator)
53 Jag MK VII (On going Frame Off Resurrection)
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