Alternator and battery problem.

[sMeYeF]

Ok so I got my car back from the electrician after a month and straight from the garage it was having similar symptoms of that before my alternator failed previously.
I was unable to go back as i picked it up as it was about to close and haven't had the time to call in about it.
Warning lights are showing which indicate that the alternator isn't running but this time it's at random times instead of it being based on revs.
The cars been driving for half a week to a week in this state.
So the question is can a bad battery cause the warning lights to appear and can a bad battery destroy what is assumed to be a good working alternator?
The alternator is that of an oval connection but came with an adapter.
Could this problem also be caused from the alternator being bad of the adapter being bad.

[GDII]

Maybe it's the battery being damaged from being flattened all the time. Did you get the replacement alternator tested or was it a reconditioned one?

Bring it over in the weekend and I'll run some tests.

[sMeYeF]

Will do It was meant to be reconditioned.
He tested it before it sent it.
I'll try get a hold of another battery that arent the 2 ive been using.

[sMeYeF]

Reconditioned alternator and a brand new battery but the warning lights that say the alternator is still on any ideas?

[mcphail]

Reconditioned alternator and a brand new battery but the warning lights that say the alternator is still on any ideas?

Have you done the basics.
Tested battery voltage
Tested battery voltage with car running and alternator connected
Tested voltage at alternator with car running.
Checked all alt fuses and belts.

[GDII]

Yip, all the basics checked. As it's intermittent it's hard to pin point. I even put in my known good battery and the alternator worked fine when tested.
We suspect it's the alternator being bad again even thought it's a reconditioned one.

Battery voltage with car running and no warning lights, 14.7V, with warning lights on, 11.2 and dropping. Take the battery out and the voltage is 12.4V.
When the warning lights are off, the alternator works fine. The question is, why do the lights come on and go off.

[clawnz]

Just a thought. Check and clean contacts for the (I think 7.5amp) fuse in the fuse box in the engine bay. As when that blows that can show low voltage when motor running and dash light is showing. Turn motor off and voltage comes back up, due to no current draw.
Electronics is not my game, but had someone show me this when I had a problem on one of the MR2's

[mcphail]

Intermittent problems suck.
Mine did the same turned out it was the diode rectifier pack that's was on its way out.
What about the plug adapter on the alt ?

[GDII]

Good suggestion Clive, will look into that. I did check the fuses but will check again.

I haven't fully tested the 'new' alternator as we ran out of time but I can check the rectifier. If the alternator is good then it's hard to find the problem.

I unplugged the adapter and had a look at it, seemed fine but I'll run some tests on it. We had the original battery in the car and it stopped working, then all we did was put mine into it from my MR2 and it worked again. So it's less likely to be the adapter harness.

[mcphail]

I have a spare alternator lying around not sure what state it's in but you're welcome to borrow it to help with testing.im in north auckland

[GDII]

I have a spare alternator lying around not sure what state it's in but you're welcome to borrow it to help with testing.im in north auckland

Thanks for the offer, we are down in Wellington so might be a bit hard to borrow it.

[GDII]

Last weekend we took the alternator out, took the top cover off and found a screw rattling around inside. This one connected the rectifier to the voltage regulator. From what Sonik told me, it would work when cold then stop when it got hot then work again when left to cool off a bit. I suspect thermal expansion was causing the connection to come apart due to not having a screw in it, then when cooling off it would join back up. It's been working fine all week so I hope this has fixed the problem.

[Benckj]

Good find, well done.