are you sure the obc tells if the battery is low? i don't think it does because I had a bad battery before and the obc didn't read that my battery was dying. is the only way to tell if the battery is low is if the interior lights blink?
i was saying if your alternator was charging low the OBC would recognize it, but i'm not sure.
the correct way to test a battery is to load test it with a battery tester.
another DIY way is to turn on your head lights, and then start your car.
if your car is hard to start (turns over slow) or the headlights get real dim while you are starting your car then most likely you rabttery is getting weak.
haha true but when your low on cash like i am, you just gotta think about the purchases you make. hopefully my friend that's a mechanic gots a battery he doesn't need lying around. well the car is not actually pop starting but I can tell that the battery is going to die soon.