try a new terminal 1st before getting another battery but make sure terminals (where they make contact in the terminal & the batterey post are clean/shiny- take sand paper to them if you have to) and make sure they make good contact all the way around. Re: lights etc ... lights only need few amps - 2-3. Starter needs almost 200amps alone. That's why batterys are like 600 amps these days. That battery has to supply like 200amps to starter, amps to ignition and all the other electrical circuits all at the flip of your ignition switch. Good connections are critical to our cars - tight, clean, and good wiring.