just as the title says my battery guage goes all over the place. it reads good when im in park but in any other gear it lowers tremendously. when i accelerate however the batter guage will go up. however when i get on it i get low battery signal. what could be the cause of something like this? ive replaced both the battery and terminals and still not workin right. shouldnt a battery guage be reading the same thing at a constant?