[Stroverlander]

This has probably been discussed here before, I searched but didn't see anything...

Recently my '04 Astro LT AWD w/90K has had an intermittent battery light showing and voltage dropping below 14V on the voltmeter and test meter at times. I tested the battery and alternator with the original AC Delco battery being most suspect with the weather getting warmer here and so replaced that with a new Interstate Megatron Plus. In checking and testing the alternator while installing a new belt tensioner/belt and fan clutch and checking grounds and power leads, I came a across a loose and sloppy fitting connector on the alternator. The connection was poor causing the intermittent battery light and other condition so after a bit of fiddling with the connector to tighten it up and make better contact, the problems have gone away. I will still probably replace the alternator soon as I am not fully happy with it's output and replace the suspect connector.

Later...

 

[Matrixx]

Thanks for information DiModaCorse, it's good to know what to look for.

 

[GaryZ]

It seems that many folks are at a loss when their battery acts up. There are a couple of very simple checks that will quickly point in the direction of the fault;

1) Check for around 14.5V when the engine is running. This can be as easy as looking at the dash voltmeter, or you buy a $10 voltmeter and touch the leads to the battery terminals (red goes to positive. . . ). 14.5V means the charging system is working. The charging system includes the alternator and associated wiring. If the voltage is 12V or less, the charging system is not functioning and the car is running on the battery (until it runs down). Most auto parts stores can do a free test of your alternator. Take it off and take it to them. Check for good connections while removing the alternator.

2) Look at the voltmeter as the engine is started. The volts should not drop below 9V under the load of turning over the engine. Above 9V means your battery and cables are healthy. If the voltage drops below 9V the engine will turn over very slow. This is usually an indication that the battery cables or battery has a problem. Clean all battery cable ends and test again. Still less than 9V? Most auto parts stores will load test your battery for free.