How many batteries do I need for a 23' hydrasport bay boat?

[Andy Knisley]

Here's my problem. My 23' bayboat was set up at the factory with a wired system for a trolling motor. This system is a plug in at the bow that runs to a 4 battery charger in the console.
From the charger I have 4 leads to 4 batteries.
Seems simple!
Here's the problem......
I have two group 27 batteries designated for starting the engine.
But, last weekend I bought a minnkota riptide st that must run off 3 deep cycle batteries.
Here's my questions:

1. Could I piggyback the two batteries for the engine?
2. Do I need 2 starting batteries?
3. Could I find a single more powerful battery that would take the place of the orginal 2 starting batteries so I could gain the room for the additional 3 trolling motor batteries?
4. Could this minnkota riptide ST be maintained on just 2 deep cycle batteries instead of 3?
I would appreciate anyone's help.
Thanks

 

[Silvertip]

Although you've given us lots of information you left out the most important info:

1) We have no idea why you need two starting batteries since we don't know what engine is on this boat or what it's horsepower is.
2) We must assume the trolling motor requires 36 volts since you said it takes three batteries.

So -- unless the boat engine is a diesel (and a large one) I would say you do not need two starting batteries. One large starting battery should be fine. A pair of jumper cables would allow you to jump the starting battery from ONE of the other three should the engine fail to start. Battery power is designated generally by group size such as 24, 27, 31 etc. The bigger the battery is physically, generally the capacity (amp/hours) is higher. All of this is specified on the label.

No -- you cannot run a 36 volt troller on two batteries. 36 volts requires three 12 volt batteries wired in series. Two batteries in series provides only 24 volts.

I contend you have enough batteries if they are in good condition. Charge them and have them load tested at any auto store.. They just need to be configured differently. You also need to check the wiring for the troller. If there are two separate wires from each battery going to the connector at the bow, the boat was set up for a 24 volt troller. With that in mind, you need to change that wiring from four separate wires, to a three batteries in series which results in only two wires going to the connector at the bow. If there is an accessory socket intended for 12 volt power then that needs to be disconnected or else a separate feed is required from a single 12 volt source.