Using the same power source for fish finder as the trolling motor

[lockinload]

I see posts about not doing this.  Are there not some kind of ferrule that will clean the power line up?  That beautiful 12 volt power right where I need it, I wanna use it.  What says the hive?

[TNDiver]

I think the issue is what happens when the TM runs the battery down and then you don't have your fish finder or vice versa.  The TM will draw a lot of power away from the battery, depending on usage. 

[Princeton_Man]

I see posts about not doing this.  Are there not some kind of ferrule that will clean the power line up?  That beautiful 12 volt power right where I need it, I wanna use it.  What says the hive?

Ferrite rings/coils likely wouldn't be enough. A TM draws a massive amount of current compared to your finders. For most folks, a cranking battery handles three or more graphs, pumps, and even shallow water anchors.
I run one group 31 Duracell AGM for cranking and electronics. While I don't have shallow water anchors, I have had all three graphs on as well as livewells running and for a while a Hydrowave for 8+ hours and never had any issues starting. In fact the cranking battery usually completes charging long before the TM batteries.

[FD]

The interference from the TM will kill the screens on newer electronics.  Most manufacturers specifically say to NOT use the same batteries.  That will probably void your warranty.

I moved my Talons and aerators to my TM batteries to conserve cranking battery.

CPF Lures Pro Staff
CPFLures.com