What battery to use?

[QC Willy]

Recently bought this boat. I have 24V trolling motor up front and one battery in back to start the motor and for 2 depth/ fish finders. Last weekend while trolling around the lake for about 5 hours, the battery was dead and wouldn’t start the outboard. It appears to be a newer battery but there’s no date markings on it. I am going to replace this. Should I use AGM deep cycle battery? What are your thoughts?

 

[FunInDuhSun]

You should get a pair of dedicated batteries for the troller and finders, and keep the starting battery just for STARTING. That’s how most bass boats are setup. Won’t hurt to keep a jump box onboard, too. JMI.
Even my little Jonboat has a separate troller battery.

 

[dubs283]

The 24 volt trolling motor should be set up with two independent 12 volt batteries wired in series to create the 24 volt supply

The main engine should have a dedicated 12 volt battery/batteries wired in parallel separate from the trolling motor batteries

If your boat definitely only has one 12 volt battery for the main and trolling motor the trolling motor is 12 volt or if truly 24 volt has not been operating up to par, if it even worked at all

In any case it's wise to operate accessories on a dedicated 12/24 volt system separate from the main engine battery

Deep cycle for the trolling motor and accessories, cranking/starting for the main engine

 

[QC Willy]

The 24 volt trolling motor should be set up with two independent 12 volt batteries wired in series to create the 24 volt supply

The main engine should have a dedicated 12 volt battery/batteries wired in parallel separate from the trolling motor batteries

If your boat definitely only has one 12 volt battery for the main and trolling motor the trolling motor is 12 volt or if truly 24 volt has not been operating up to par, if it even worked at all

In any case it's wise to operate accessories on a dedicated 12/24 volt system separate from the main engine battery

Deep cycle for the trolling motor and accessories, cranking/starting for the main engine

They are separate. 2 deep cycle 12V batteries at the bow for the trolling motor and 1 12V battery in the stern for cranking and electronics.

Are you saying I should get a different 12V battery just for the electronics?

 

[dubs283]

Two things you could do. One is add a second deep cycle battery parallel with the main engine cranking battery with a 1, 2, All battery switch and select the deep cycle (2) battery when using electronics with the engine not running.

Two is the same scenario but with an isolator for the main and deep cycle battery, this way only the deep cycle is used for power with the engine not running thus "saving" the #1 battery for engine starting/running