Having a problem with a battery. Maybe just not big enough. I have an older merc 200 EFI, recently rebuilt. Starting battery is a group 27, 1 year old and tests good at the shop. 816 CCA. I have finders and live well on it. Running the finders only, I have the Helix 10 shutting off when I start the motor. I also get low voltage.
This is a regular battery, not a marine or deep cycle. Is this really not big enough or should I check something else?