'90 spider alternator

["Graham Hilder" <graham.hilder@domain.elided>]

In no.1194, Derek asked about a battery problem in his Spider:

"The battery has died twice after the car sat for about a week or two each =
time. The second time was with a brand new battery.  I couldn't find =
anything electrical left on. I took it to my shop where they ran a =
battery/charging system check.  The battery was fine.  The alternator =
output at idle was 15A, and max output was 40-42A. My shop manual says the =
max output should be 70A.  Is it time to replace the alternator?"

Going by the above, Derek, I wouldn't think that  replacing  the alternator=
 to gain a higher output would fix the problem..... the problem's =
happening while the car's sitting around and the alternator's not running =
anyway. In any case, a 40A output doesn't seem too terribly bad..... =
should be enough to cope with most normal useage I would have thought, =
although I guess US cars can have a lot more electrical loads on them than =
our NZ ones usually do. (30A is all we need in an oldish Alfa ! ).

Before splashing out on a new altr, I'd get hold of an ammeter and see if =
there's any significant current draining from your battery when the car's =
sitting around with everything off, and try to trace it.  I guess it could =
be that there is a fault in the alternator which is draining the battery =
(e.g. diodes), in which case yes, fix or repolace the altr.=20

But if the altr is charging the battery OK (and you don't have this =
flat-battery problem if the car's in regular use), and if the altr isn't =
draining the battery when car is at rest, then I wouldn't think changing =
the altr would help.

Any other opinions, anyone ? (I'm only an amateur!!)
Regards,
Graham in NZ
(71 GTV, 77 Alfetta, 82-82-84 Alfasuds)

------------------------------