I just started having trouble with my cranking battery. I've ruled out the battery (I think) but the motor seems to not charge the cranking battery when I run it. in fact if I start the motor more than 3-4 times it kills the battery. The battery definitely takes a charge no problem, so I thought maybe my alternator is bad? any thoughts or advise? this all started happening the day after I replaced the Lowrance LMS 480 at the console with a Humminbird 797. is there anything under the console I could have screwed up that would cause this?

2002 150 VMAX fuel injected