Since He (Creativead) has your attention. I have a similar problem but I have 2 coach 1 chassis battery wired in series. The problem is occasional and seems to be more of the shoreline not maintaining. I will loose power after some hours of use. All connections appear clean and tight although I haven't physically disconnected any as of yet. Not sure where to start. I was thinking to first test each battery. When testing in series do I need to disconnect first or can I test as they are wired together. I have not worked with series before so just need the basic starting point. thanks.