On 05/17/2018 01:11 AM, wrote:
> My 99 Explorer had been running fine. Tonight I left my lights on, killed the battery - which is about a week old from Walmart. Boosted it with another battery I have that happens to be good. Car fired up but the connection nut with the rubber boot at the top of the alternator started glowing red hot. Obviously can't run it like that.
>
> Any ideas what's happened? Never encountered this before.
>
> Thanks.
>
Hello, and if you're talking about the output terminal (not the field
coil terminal), then perhaps one or more of the internal alternator
diodes is/are shorted. Motor vehicle alternators are three-phase AC and
supply that to a full-wave, six-diode rectifier bridge assembly. Those
diodes can be internal or external to the alternator but most of the
time they're internal. A shorted diode or two could allow for the flow
of battery current to ground (car frame). Sincerely,

--
J. B. Wood e-mail: