Ignorant Alternator Question for 87GN

[Mercury7]

I know that over time these original alternators simply fail.

Has anyone ever had one partially fail?
My car typically sits for about 2 weeks at a time, and if I neglect to start it up during those 2 weeks the battery usually needs a jump.
After that, everything operates normally.
And if driven or just started every couple of days, there's no issues with battery.

Last weekend, it needed a jump.
Drove it about 10 miles and after turned car off it had no electrical power at all.

Turn key & no crank, no power at all.
I got a jump, jumper cables on for about 2 minutes and I noticed the Voltage trouble light was on when it started.
Never seen that Voltage trouble light on before.

It had stopped cold again by the time I disconnected the cables and put them back in the trunk.

Got another jump, jumper cables on again for another 2 minutes.
I got in the car right away in case it stalled again.
Voltage trouble light on again.
It started to sputter a little, throttled up in Park and still stumbling.
I'm pretty sure that the Tachometer wasn't even moving that time; and it stopped cold again.

Brought it over to local garage and they determined alternator gone bad.
They said would fully recharge battery.
So it's been sitting since Thursday or Friday while I'm waiting for parts.
I stopped over earlier tonight to get some gear out of the trunk and noticed interior lights and trunk light at full strength.
I forgot for the moment that they had fully charged the battery.
But then I started the car and it turned right over, full power. and no hint at all of any trouble.
I let it idle up to about 180 temp. and shut it down.
Then started it again immediately, again running normally, no stumbling at all.

Any thoughts?
Thanks.

 

[Phoneguy]

Sounds like you have something that is draining your battery and/or a bad battery. How old is the battery? Have you tested the battery under load?

Bryan

 

[dsapper]

1st check for a drain on the battery. Use a multimeter between the battery and the positive cable and check if there is a draw. If so you have a short, culprit #1 is the fan relay on the drivers side of the fender.

If you don't have a draw it may have just been the voltage regulator on the alt had gone bad. If there is no draw I wouldn't worry about it

 

[Turbotre]

I know that over time these original alternators simply fail.

Has anyone ever had one partially fail?
My car typically sits for about 2 weeks at a time, and if I neglect to start it up during those 2 weeks the battery usually needs a jump.
After that, everything operates normally.
And if driven or just started every couple of days, there's no issues with battery.

Last weekend, it needed a jump.
Drove it about 10 miles and after turned car off it had no electrical power at all.

Turn key & no crank, no power at all.
I got a jump, jumper cables on for about 2 minutes and I noticed the Voltage trouble light was on when it started.
Never seen that Voltage trouble light on before.

It had stopped cold again by the time I disconnected the cables and put them back in the trunk.

Got another jump, jumper cables on again for another 2 minutes.
I got in the car right away in case it stalled again.
Voltage trouble light on again.
It started to sputter a little, throttled up in Park and still stumbling.
I'm pretty sure that the Tachometer wasn't even moving that time; and it stopped cold again.

Brought it over to local garage and they determined alternator gone bad.
They said would fully recharge battery.
So it's been sitting since Thursday or Friday while I'm waiting for parts.
I stopped over earlier tonight to get some gear out of the trunk and noticed interior lights and trunk light at full strength.
I forgot for the moment that they had fully charged the battery.
But then I started the car and it turned right over, full power. and no hint at all of any trouble.
I let it idle up to about 180 temp. and shut it down.
Then started it again immediately, again running normally, no stumbling at all.

Any thoughts?
Thanks.

Sounds like dirty battery cables.

 

[gnpoweredrail]

I was going to say the same thing...or even just loose

 

[novaderrik]

bad battery
bad cable(s)
loose connection- especially on a ground wire.
battery cable bolt too long- some bolts will bottom out in some batteries and you'll never get a good tight connection. problem seems to have gotten worse over the last few years- i think the battery manufacturers changed the depth of the threaded holes on the battery.

the alternator can be checked at any auto parts store- usually for free.

 

[Red C5]

Start with getting the battery checked out. Also most auto parts stores have equipment to test your battery and alternator right in the car.

Peter

 

[EYE-OPENER]

Alternator could have a bad diode. It would slowly discharge when sitting and not fully charge as needed. If you let the car sit overnight, grab the alternator and see if it's warm to the touch. It will be warm if that is the case. You can disconnect the alt plug as well and see if it still happens. The bench tester the chain stores have most of the time wont detect this issue. Bring the alt to a rebuild shop and have them pull it apart to see if that is the case.