You will want to charge your battery before you put a load test on your battery. The battery should have at least 12.4 volts in the battery for you to put a load test on it, if you put a load on it with fewer than that it can mess up the results. So if you can take the battery out of the car and charge it up all the way to make sure that its the battery. As the alternator will kill the battery if it is bad or going bad. So you could have a bad battery and bad alternator if you keep it going too long.