Hello Everyone,

I just set up my two batteries on my project boat and I want to make sure that I'm set it up correctly before connecting my trolling motor. My Motorguide is a 12v. I have the two battery's running to an A/B switch and each is grounded to a grounding block. I ran 6 gauge from the "COMMON" on the back of the switch up to the trolling motor. My freind put the switch on "BOTH" and he claims that the total output is 12v's. Would it be OK for me to run the motor on both or do I need to run one at a time?  :-? I hope you guys can help me.

Thank you

I would get me a couple of battery jumpers and connect both positive post together and both negative post together and not mess with a swith. You can buy short jumpers that have will go on the lead post of each battery so you don't tie up the studs. You will actually get a longer run time pulling off both batteries in parallel than running off one battery until it dies and then switching to other.

As long as the A/B switch is connected in a parallel configuration, your friend is right, it's better to run in BOTH.

I put in a second trolling motor in my Tracker and Billy Wells of Wells, Inc., the leading trolling motor repair shop in the greater Richmond, Virginia area, told me to cross wire the two batteries.

That is... positive to negative and then negative back to positive.

Cross wire them.

So far, it works!

I suggest calling a boat service or repair shop just to make sure.

Thank you for the tips, I'll keep you guys posted.

I don't want to get into no word battles but you CAN NOT cross connect two batteries as you have described.  They would melt down or blow them up in your face.  

There are only two ways you can connect them.  One is a series connection that gives you 24 volts.  To do this you connect The TM positive cable to the positive post of battery A.  Connect the negive post on battery A to the positive post of battery B, connect the negative post of battery B to the negative TM cable.

The other is parallel where you connect battery A and B positives together and battery A and B negatives together.  This gives you 12 volts but at twice the amp hour capacity of one battery.

If I read your post correctly you will only be running off of one battery at a time useing an isolating A/B switch when set to either A or B. That allows you to keep one battery as a reserve.  That's the way I would probably go, and I think it would give you the most over all trouble free results especially when chargeing.  The Both setting, should still be 12 volts and I don't see why you couldn't use it like that.

You can hook batteries parallel A+ to B+ and A= to B= and still get 12volts. If you hook them in series A+ to B- and A= to B+ that will give you 24volts and maybe way too much voltage for your trolling motor to handle.

Two problems I have found when running batteries that are linked parallel "directly" to each other is that unless they are both in relatively in the same condition the weaker battery can eventurally drain bat. life from the stronger one also over chargeing can be a problem to one battery unless you use a switch or charge them independently.

http://www.motorguide.com/index.pl/12_volt_and_24_volt

Thank you. I have decided to run them one at a time and switch to the second when the first is running out.

Hey guys, you all are right.

I put in the second trolling motor to get to 24 volts as I upgraded my trolling motor from 12 to 24 volts.

Sorry for any confusion I created.