Wiring trolling motor batteries

[slammer]

I have a Minn kota bow mount motor, 55# Auto pilot. Would like to hook two 12 volt batteries together for more running time. Any tips on the right way to do this? Do the batteries need to be the same brand and age? How long should the wires be between batteries. What size wire should I use? Circuit breakers? New male and female plugs? I know a little about this but I think its just enough to get me in trouble. Would appreciate any help and ideas.

Thanks

[Pherris]

I would reccomend you just carry the extra battery and switch it when you lose power in the first, that way you know you will hook it up right. Also if you hook them togehter you will be runnning a 24 volt system and I think your motor is a 12 volt. I am not 100 % sure but you may want to check that. Good Fishing!!

[Northlander]

You can hook 2 up and still run a 12 volt system but when I had a 12 volt I would just switch over to the fresh abttery as needed. That way I knew how much life I was getting out of each abttery that given day.

[MuleShack]

Here is a diagram for you to reference.

If your motor is a 12v, you simply connect both positive terminals one the batteries together and connect to positive lead to motor...and do the same with the negatives. called Parallel Connection

If your motor is 24v, then you run red to black between the batteries and hook your red lead up to the open positive lead on the battery #1 and run the black lead to the negative on battery #2. Called Series Connection

Hope this helps.

[slammer]

My motor is 12 volt, sorry forgot to mention that. What kind of switch do you use on your single battery setup or do you just move the wires from one to the other?

[Northlander]

I used to just move the wires it would take me about 2 minutes.

[jwhjr]

I have 2 in my boat and just switch over to the fresh one when necessary.

[raymondk]

One thing that never is addressed I rewired my boat i have live well lights and the rest of my electrical ran off of my trolling motors batterys in front of my boat . I have my starting motor battery in the rear for the motor and just the dept finder . this setup has been working real good for me i run one battery dead and just switch wires I never run out of juice . now if i had a 24 volt trolling motor I would have to run everything off of my starting battery again since nothing else is 24 volt this is never brought up there is nothing worst then trying to start your motor and it is dead from running your live well or lights on to long. there is a down side to going to a 24 or 36 volt system .

[Whoaru99]

Actually, you probably get more total power from running the two 12V batteries in parallel than running each one separately.

Batteries put out less total power the faster they are drained. So, when the batteries are in parallel, each discharges more slowly and gives up more total power.

If the discharge rate is very low, it's probably about the same either way.

[Surface Tension]

I have the same motor.

I use one(good)battery but in my usage a battery last all day easily.

If your battery is good and your needing to change batteries then by all means wire in parallel.

Batteries should be same type and size if your using both in parallel. I mount my battery in bow storage, I like the weight up there plus its a sort run to the motor. 6 gauge wire minimum and if your coming from the stern go 4 gauge.

[marine_man]

now if i had a 24 volt trolling motor I would have to run everything off of my starting battery again since nothing else is 24 volt this is never brought up ...there is a down side to going to a 24 or 36 volt system

Actually, you can connect 12V appliances if your batteries are connected in series. Connect the negative to one battery and the positive to the positive post of the same battery. You're in business then.

marine_man

[BobT]

Quote:

Batteries put out less total power the faster they are drained. So, when the batteries are in parallel, each discharges more slowly and gives up more total power.

Yes and no, I believe....sort of.

I'm not a battery expert but it is my understanding that the batteries are capable of delivering X amount of total power over a given period of time no matter how fast it is taken.

What does seem to happen is when you use a deep cycle battery for while and then stop using it, the chemistry in the battery will to some degree rebuild its charge. When you use one battery and then switch when it starts to get low, you will find that after a period of time that battery will have a little reserve power at your disoposal. I think when you connect two in parallel so that the current draw is lower per battery, the draw is low enough that this reaction is able to keep up with the draw.

When using one battery at a time you might be able to obtain the same use time by switching back and forth a few extra times. In either case, it isn't really the best thing to cycle a battery too deep. I don't remember for sure but avoid cycling deeper than 80% comes to mind.

Bob

[slammer]

Thanks for all the input. I think I'll just use two separate batteries and make the switch when one dies. Do you think the day will come when we see an electric outboard motor? Might be sooner than we think with gas so high.

[BobT]

They already exist up to certain horsepower but not quite sure how big. I've heard of 4hp but maybe more?

Bob

[Whoaru99]

I think I'll just use two separate batteries and make the switch when one dies.

This really isn't that good of a plan.

The more deeply you discharge a battery, the shorter the lifespan. If you use a battery until it's essentially dead/very low on power, that's VERY hard on it.

When they are in parallel each battery is less discharged per cycle which helps to promote longer life.

Also, if you connect the batteries in parallel, you don't NEED to mess around with any connections to use both batteries.

[Whoaru99]

Nope. The faster you discharge a battery, the less total amp-hours you can get from it.

Directly from the Trojan battery HSOforum...

Their group 27 deep cycle is rated at 115AH on a 20 hour discharge curve (~5.75A load), but that same battery yields only 95AH if discharged on a 5 hour curve (~19A load). Going even further, Trojan specs the battery at 200 minutes reserve capacity @ 25A load, or 52 minutes at 75A load. If you do the math, that comes out to about 83AH and 65AH respectively.

So, as you can see, the usable amount of power delivered by the battery varies quite a bit depending on the discharge rate.

This just goes to show even more clearly why putting the two batteries in parallel is advantageous for longer battery life - both in on the water time and in lifespan.

Please don't take it the wrong way, but those who are using one battery at a time are actually doing more work for less return.

[BobT]

Good to know. Good info.

Bob

[NELS-BELLS]

You can hook 2 up and still run a 12 volt system but when I had a 12 volt I would just switch over to the fresh abttery as needed. That way I knew how much life I was getting out of each abttery that given day.

I want to purchase another battery for my trolling motor. I don't want to hook them up parallel because one battery is older and together they are only as good as the weakest battery. Also I like knowing that if the first one goes dead, that I have a fully charged back up.

My question is do they make a switch (simple A B switch) that you can hook them both up and switch from one battery to the other? Rather than unhook the wires every time, because I don't have room to put both batteries next to each other.

Nels

[marine_man]

Take a look at a Guest brand battery switch. It should work for what you're looking for.

marine_man