Did you know that new car battery you just bought may not be fully charged?
Batteries lose some charge over time sitting on that shelf. They even have a shelf life and can go bad. So, especially with car batteries new doesn't necessarily mean good or fully charged. I'm not a parts store. I'm a repair shop. I only keep on hand a few (five) of the most popular batteries. But I run the trickle charger through the bunch at least once a month and test each one at that time. When I have to get a battery delivered I test the battery and the charge state before I install it. I've learned a few things like that over the years. You don't want to put a discharged battery, or a bad one on a car and cause the alternator to have to overwork to charge it. The alternator isn't on there to be the battery charger. Which brings up another point....
You may have another problem that caused the battery to fail.
Once you have installed the correct, fully charged, good battery with clean, tight connections and proper mounting, you'll need to test the charging system and measure current draw.
