Do I need a 4th battery

[jamokebob]

I have a 2021 190 TXW. It is equipped with two 27M deep cycle batteries for the Ultrex 24v trolling motor. I also have a 27M starting battery for the engine and electronics including a Helix 10 fishfinder and a Mega 360. I upgraded this battery from a 24M when i added the Mega 360 and changed out the fish finder from a 5" Lowrance to the Helix 10. I will be adding another Helix 9 fishfinder this winter. Do I now need to add a dedicated battery for the two fish finders and Mega 360 or can I just power it from the exsiting starter battery?

[GeauxTide]

I had end of day cranking problems with 2-7" Helix plugged into my 27 Interstate. Swapped to 31 Die Hard AGM and no more issues.

[Extremeboating]

Keep it three. Ditch those two batteries for your troller, change one to a single lithium 24V for the troller and make the other one which would otherwise be for the troller, a dedicated electronics only battery. The other will be used strictly for cranking.

[blkfalc4]

A 10", 9", and 360 doesn't need a dedicated battery imo. Kind of overkill.
Run what you have, you'll be able to gauge if you need and when you'll need to upsize the main battery.

[bassfisher444]

Just switch to a group 31 starting battery and you will be fine, I run 3 9" graphs off of mine all day without issue.

[jamokebob]

I'm most concerned with the power draw upon starting the engine. The graph may become damaged if I forget to turn it off. I was thinking the best thing to do would be to add a 4th dedicated electronics battery in the starboard fishing pole locker. I was planning on a Lithium battery but since I am in Arizona and the temperature exceeds 113 sometimes during charging, I changed my plan to an AGM battery.

[bassfisher444]

I'm most concerned with the power draw upon starting the engine. The graph may become damaged if I forget to turn it off. I was thinking the best thing to do would be to add a 4th dedicated electronics battery in the starboard fishing pole locker. I was planning on a Lithium battery but since I am in Arizona and the temperature exceeds 113 sometimes during charging, I changed my plan to an AGM battery.

Why would the graph get damaged from starting the engine? The worst that could happen is the voltage drops and you get a low voltage alarm on startup. I have a Diehard group 31 lead acid commerical starting battery, and I run 2 Garmin 93sv units, Lowrance Elite 9, Power poles and my livewel on it all day and have no issues cranking the motor.

[jamokebob]

Keep it three. Ditch those two batteries for your troller, change one to a single lithium 24V for the troller and make the other one which would otherwise be for the troller, a dedicated electronics only battery. The other will be used strictly for cranking.

I would love to switch to lithium but.... I live in Arizona where the summertime temperatures exceed the 113 degrees charging max.