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Can bad alternator drain battery while car is off?
Posted: Mon Sep 21, 2015 6:53 am
by martyf250
still trying to figure out my electrical issue. Can a bad alternator drain my battery (fully charged) overnight while the car is off?
Re: Can bad alternator drain battery while car is off?
Posted: Mon Sep 21, 2015 7:15 am
by eieio
martyf250 wrote:still trying to figure out my electrical issue. Can a bad alternator drain my battery (fully charged) overnight while the car is off?
yes, Marty..........
from my post in your other topic on this matter...........
eieio wrote: and it seems to me that there have been alternator failures causing the battery to drain while parked
Posted: Mon Sep 21, 2015 7:19 am
by martyf250
thank you for the reply and help!
Posted: Mon Sep 21, 2015 7:25 am
by eieio
martyf250 wrote:thank you for the reply and help!
.......you're welcome
Posted: Mon Sep 21, 2015 12:42 pm
by smj999smj
The alternator can short-circuit internally, which would create a significant parasitic draw when the engine was not running. To do an overnight test, you could remove the alternator fusible link; it's often the one with the highest amperage and, depending on year/model, will usually be in the 75A-140A range. If easily accessible, you could also just disconnect the large wire to the back side of the alternator (at the "BAT" connection post). It'll be held on with a 10MM nut.
Posted: Mon Sep 28, 2015 8:09 am
by martyf250
was indeed the alternator. appreciate everyone's help who replied