Good evening, long time lurker and have enjoyed all the knowledge that I have gained from this forum.. I am typically a South Texas Coast fisherman but occasionally enjoy fishing freshwater too (especially after the coastal freeze). Recently I bought a new Humminbird Helix 10 Mega SI+ and have had nothing but problems. The first unit I purchased in December completely blacked out while I was at Choke Canyon. I contacted HB customer service and they sent me a replacement head unit. This evening I went to Calaveras Lake to run the boat and mess around with the graph and noticed that after about an hour of use the 2d sonar completely stopped graphing the bottom. It seemed that the SI and DI would work fine but as soon as I switched to the 2d I would loose the bottom. The unit is hooked directly to the Optima blue top battery which is also the cranking battery. Do you think its loosing voltage thus not working correctly? Any input would be appreciated before I have to contact Humminbird again

Turn on the readout boxes and set one to show Volts. Then you can answer your own question.