well, here's what I think,..there is a huge parasitic amp draw on the chassis side... so when it's off it is bottoming out the battery, a couple times is all it takes to kill the battery,,the thing to do is a battery disconnect when you know you will be parked for a few days..I put one of those tenders on once that disconnects the battery when it see the battery at 12v... or 11.9 I forget...
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