Battery Problem?Help.

[slamX5]

My 2003/MAR X5 doesn t work after I have a 2 month long trip . Then the dealer replace a new battery under warranty on Sep1. 2weeks ago it does t work again, i jump the battery and send it to dealer.They have a drain-test for the electrical over 30 hours and said the water-pump drain the battery abnormally and fix it. I get it back after 2 days it stuck again , they said the battery may be damage after the water-pump long-terms drain. Then they change a new battery again. When i back to home. i charged it with the oem-charger over 15 hours. It still red light on. How long charge for a new battery ? I m so scare back to dealer . Guys , do u have any suggest ? I drive my X everyday. The charger is brand new and charged next BMW succesful.