I have two batteries wires in series to power my Minn Kota trolling motor. Also, I have the outboard starter, lights, live well, bilge pump and fish finder.

One pair of wires (pos/neg) powers the lights/bilge/live-well.

The other pair of (pos/neg) wires is for the fish finder.

The last pair is right off the evenrude outboard motor.

In the past, I'd connect all positives to the positive terminal and all negatives to the negative terminal on the single battery that came with the boat.

I recently bought the new trolling motor and an additional battery. I wired them together in series and connected the trolling motor, which ran fine.

So now, I'm not knowing where to connect those other pairs (of pos/neg wires) to?

I'm hoping that I don't need to buy an additional (third) battery. Do I?

The way it should be ran is that every single thing in the boat including the outboard, pumps, fishfinders, lights etc. is connected to the cranking/dual purpose battery with the exception of the trolling motor which needs two batteries wired in series itself. So 3 total batteries for the setup that you have now as long as you have a 24v trolling motor.

X2

X2

What does X2 mean?

It means he agrees and so do I but if you can't afford or can't have the extra weight ... You can wire the 2 batteries to get 12v from one battery and 24v from the other 2

Do a google search for a wiring diagram for a 12 and 24v wiring

You run the risk of interference on the graph from the trolling motor. More importantly, if you're on the TM all day, you run the risk of the outboard not starting because of being drained. Ideally, you want a total of 3 batteries. 

1 battery for cranking /accessories

2 batteries for 24v trolling motor  

 

only sensible way to do it......doing it another way is asking to stranded one day.

It means he agrees and so do I but if you can't afford or can't have the extra weight ... You can wire the 2 batteries to get 12v from one battery and 24v from the other 2

Oh ok... That's new. I've only seen "+1" when someone agrees. LOL - I can't keep up with all these (new) cyber-slang terms  

 

Thanks for the inof below, I'll look into it, although I'm favoring just getting another Everstart from Walmart to pair up with the one I have. I'll keep the Interstate for the cranking, lights, sonar, etc..

 

Thanks again!

I hate to bust your bubble, but when you buy and connect a new battery in series with the battery you already have, one of them will be dead before very long. 

 

When you connect two batteries in series (which is necessary for a 24v TM) they both should be the same.  Same age, same type, same manufacturer and a same size.  In other words, the are identical twins.  That's where those cheap wally world batteries will drive you nuts.  You buy two brand new ones, and one goes bad eight months later.  They are only going to replace the bad one, so you install the replacement with the first battery, a few months later, ones dead again.  You get hung up playing battery ping pong.   They both have to be replaced.  You can't put a new battery with a like battery that has been charged over 25 times without having possible problems.

 

The batteries must have similar internal resistance, since the same amount of current is passing through both.  If one has more than the other, the one with the lesser amount will be working twice as hard, and the one with the greater amount will be overheating.

 

As far as wire connections, the TM should be the only thing running on the two TM batteries.  All other wires will connect to the cranking battery.   That's also why you should only use BIG, at least group 27, dual purpose cranking batteries.

The way it should be ran is that every single thing in the boat including the outboard, pumps, fishfinders, lights etc. is connected to the cranking/dual purpose battery with the exception of the trolling motor which needs two batteries wired in series itself. So 3 total batteries for the setup that you have now as long as you have a 24v trolling motor.

 

X3