Two things, your battery is or has failed, or your alternator can't handle the load your asking for. Have the battery load tested and get the charging system evaluated as well. Most likely alternator can't keep up, especially if it's the original and the brushes have never been changed. Get it looked at ASAP, this will not go away, especially with the cold weather in your face, so to speak..

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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.