Unless you have bought a battery already have it charged and checked, most auto parts stores will do it for you.
I work with electronics and have had more than my share of capacitors go off on me. I even had a cir work perfect till I disconnected the power supply and reconnected it. POOF-POP-FLAME! double checked I didn't do something wrong and tried a second cir and it did the same thing with the same 100% verified correct setup.
