The two places to drain the coolant are through a drain plug on the right side of the engine block and a plug on the bottom of the radiator.

I have done a number of coolant changes, and can say that I have never heard of diconnecting the battery to drain the coolant.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record