I have a similar setup as Brian with the 570 di mounted on the bow and the tranducer mounted on the trolling motor. I have the unit wired to a dedicated
lawnmower battery so that it is the only thing on that battery. My problem is that the unit will be working correctly then all of a sudden the depth reading will
change to a deeper depth reading and start continously blinking. The displayed will also be acting up, I can run through several display modes and correct it and
sometimes I have to shut the unit down, let it reset, and turn it back on. These are only temporary fixes as will eventually act up again. The problem seems to
be happening in the 10 foot depth range and it does not matter if I am using the trolling motor or not because I have had happen in either case. Sometimes it
will only take a few minutes to start happing and other times it might take up to 30 mins. before it starts acting up. When the unit is working properly it is
great and I love it, but it also annoying to have this problem. Also this problem has occured from the first time I took it to the lake.