Trolling motor batteries/hook up 24v

[Alagnak]

So- I have the starting battery, and 2 deep cycle 24 V set up dedicated to the trolling motor as normal. I see advertised combination 'starting/deep cycle' batteries. Are these just for guys that run a little 12V off of their starting battery?

Is there any logical way to have 2 batteries total for starting and 24 V trolling motor or is that a no-no out of question? I just figured it must be because I don't see anyone do that.

I'm just always trying to think of ways to shave weight off of the boat. I suppose I could buy the smallest size deep cycles to shave a few pounds too....

Thanks for any insight.

P

[BobT]

First point.

A deep cycle battery is really not designed to be used as a starting battery. So, can it be done? Yes but because the battery is not designed for that purpose, it can have an effect on the life of the battery.

Second point.

Using 12v from one of the series connected batteries to start your outboard may introduce interference into the trolling motor that may not be desirable. I can't say for sure if this is a real concern or not but personally, I would avoid it.

Third point.

The very best option is to use three batteries. Two deep cycle batteries connected in series to supply your 24vdc trolling motor and a dual purpose marine starting battery for starting your outboard and running your accessories. The reason I recommend using a dual purpose battery for this is because by its names sake it has some characteristics of both a deep cycle and a starting battery. It can handle the task of operating your livewell, baitwell, lights, sonar, etc. without difficulty but can also handle the rapid current draw required when your fire up your outboard.