My car had a battery problem all of the sudden i had had no clue why. Started off with the ignition being weird and would splutter before starting. It eventually – around a day after, stop starting. Lights window and everything else worked just start didn’t start. If i left it overnight, I would have to jump the car every morning. I decided to replace the battery without testing as i did not know u could even test it. My old battery had 356 CCA in my 15 toyota. I bought a 500+ CCA and replaced it. Should have I tested it first to save myself $90 on the new battery? I have no idea when was the last time the car battery was replaced as well.
You should really test your battery before replacing it because some people confuse the battery issue for an alternator issue. Hypothetically in this situation you replaced the battery and it didn’t solve your problem. You test the alternator and that’s the problem. Well the parts store won’t refund you the battery. It’s used. So you’re out the cost of a battery AND you still have to fix the actual issue.