I am a little new to boating so bear with me. I have this onboard charging box in my boat and am wondering if it the same as a battery switch or similar. Yesterday we would stop and play music (Just a sony deck no amps) and a couple times it was hard to start. When I tried to fast throttle start it, it wouldnt even turn over. I do have a couple batteries in it running so I was wondering why all the potential battery drain. I am inculding a pic so you can see what it is I am talking about. Thanks