Alternator connector glowing red hot after jumping with other battery

[Robert_P]

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.

 

[Rick]

Check all your cable connections for corrosion. Ground straps etc.

 

[imp]

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.

@Robert_P
Did this happen just as the engine was running, before or after disconnecting the booster battery, need to know conditions present when you noticed the hot-spot. You will need to remove and inspect the parts forming that connection. Either the connector is corroded and exhibiting high resistance, causing heat build-up when current flow is high, or something happened to the alternator which "fried" it.

Was the original battery near-dead when you connected the booster? Any chance you connected the booster backwards? imp