At present I have 15’ of #8 wire run to my cranking battery. I’d like to see if a lithium battery located in the bow near the black box will enhance the screen display. Before buying a lithium battery it seems wise to try a Dewalt tool battery to compare views. My thought is to use THESE CONNECTIONS to switch from cranking battery to the Dewalt.

Can I use a Dewalt 20v battery to power a Garmin 1042, black box, & LVS34?

With the connection linked above I could easily switch power sources to compare the views.

is this a good plan or should I consider something else?

Thanks,
Danny