The next thing I would do is to run a wire straight from the battery to your power wire on your graph. Just do it at home and connect it straight to the battery (use an inline fuse) and run it on the deck straight to your graph.

You could possibly have a bad connection in your current wiring causing it to have a drop in voltage.

It sounds more to me like a heat issue in the electronics as if you may have a defective component on a circuit board. It will turn on when cool but when it heats up it shuts off and turns on again after it cools off. I agree that you should run it's own power from the battery with a fuse and possibly a switch but if that doesn't fix it, I would look at sending it to Lowrance.

Go to www.lowrance.com and check for soft wear updates for your unit. See it all the time up here.

I've never heard of a HDS unit getting hot? You might have a hardware issue. Does Lowrance still support the Gen 2 units?

Well I think I ruled out the battery and connections. I put my old HDS 5 on and it has stayed on, no issues. So I guess there is an internal problem with my 1 yr old HDS 7. I dont know if a software update would address that.