ran the radio in my E36 only about
45 minutes with the engine off and couldnt start the car, got the clicking sound. got a battery boost a.drove around and car starts fine. looked at the battery and the water was low on 4 cells so that the top of the plates wasnt covered .
so i added water. are these batteries really maintenance free ? then why does the water disappear ? how do i test to see if i need a new battery ?
car is 8 years old