Hmm. I run the Helix 12 CHIRP MEGA, I know it is supposed to pull more power, but I haven't had any issues. I run my electronics off the starting battery. This past week, I fished 3 hours same spot, never turned the O/B on and the battery never dropped below 11.
If you are running a two battery system with one as a starting battery and the second as a electronics battery and are having issues, you may need the battery tested. Is your dual battery system already rigged to a dual-switch? If so, you can start in the #1 position, run electronics in the #2 position and when running the motor, use the ALL position to recharge both.
Capt. Craig Copeland
Licensed by the US Coast Guard
2013 Nautic Star 2110 Shallow Bay Boat
Humminbird HELIX 12 CHIRP MEGA SI GPS G2N
Nautic Star Boats Pro Staff (nauticstarboats.com)
Redneck Fish'n Jigs Pro Staff (redneckfishn.com)