Battery Parasitic Drain

[ballpencil]

Car is Daihatsu Charmant with 4AGE swap though i think this is unrelated.

Leaving the car overnight got the battery drained and difficult to turn the starter in the morning. I think i've narrowed the problem to the alternator since it started easier when i disconnected the thick charge wire from the batt positive before leaving the car at night.

1. If this is a case of miswiring, my alternator is the flat plug type with three pins. The middle one is connected to Ignition. I think i connected the rest of the pins (L and S) correctly since the Charge Light turned off when the engine's running. So can we rule out miswiring?

2. Rectifier diodes are confirmed normal after continuity check.

3. Internal Regulator has been replaced earlier so this can be ruled out. Alternator is charging normally when the engine's running.

Any ideas? One more thing, what happens when engine and key is off but the alternator's IGN pin still receives positive signal? Does the alternator drain the battery this way?

[litldv8]

if the alternators ign pin is still energised the regulator is still turned on which will drain the battery overnight. it is wired wrong.

[midnight_purple_GA70]

you will probably find your IG wire and S wire are back to front...

meaning the regulator will always be turned on as the "sense" wire is connected to it

the alternator will still work correctly as it will sense a voltage from the ignition wire and regulate output to suit...

charge light will see normal working conditions so will behave normally

[ballpencil]

Had i not made sure that IGN pin is the middle pin, i would agree with miswiring. However, the sticker on the alt body says so. It's only possible that i swapped the outer pins L and S but this is unlikely as the charge light is working normally.

I'll make sure about the IGN pin energized even when key is off.

[ballpencil]

oh btw, would it be a good idea to connect S to ignition also? that way i can make sure both IGN and S are dis-energized when key is off while still allowing S to read the voltage when engine is running and alt is working.