I purchased two monitors for the dual battery system on my pontoon boat.

When they arrived there were as expected a black and red wire to go to the battery terminals.  However there were also two black wires joined together.  What do they do??

I understand that if power is lost, the monitor will have to be reprogrammed….correct?

Finally,  how much of a power drain is the monitor on a battery if turned off at the monitor?  Enough to kill a battery in a month??

Thanks.