There is a big problem on the 6.  Seems some engineer decided to save $0.10.  There should be no power at the battery charge port, it?s an input not an output.  A simple 10 cents diode would of solved this problem by not allowing the current to return to the charge port.  Issue is if somehow you short the negative and positive terminals on this port the internal fuse will blow.  Not meant to be user replaceable.  Rad are trying to deny warranties based on user error when in fact it?s awful engineering, shorting the input port should not blow a fuse.  Output, that a different story.