using and engine battery to power a trolling motor

zpalffy

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I was wondering if anyone has ever used all of the juice in their trolling motor battery and then disconnected their trolling motor battery and also disconnected their outboard battery and used jumper cables to power the trolling motor from the outboard battery or if you can even do that ? Do most of you carry jumper cables ?
My concern is being out on a electric only lake and my trolling battery dies can I switch out batteries assuming both are 12 volts and can I use the jumper cables to connect the trolling motor to the outboard battery. One battery is one side of the boat and one battery is on the other side of the boat so my idea was to use jumper cables to bridge the gap. Guess I could physically switch them but they are a little difficult to get out.
 

roffey

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Here's my thought, and I would suggest you wait for someone in the know to answer definitively. In a pinch the motor battery will work. It is not intended to be drained and charged over and over like a deep cycle but maintain a constant charge so I think you will damage the battery over time if you used it all the time. As far as the jumper cables go they are intended to jump start batteries so your good to go.

now wait for the real answer, LOL.
 

zpalffy

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Thanks roffey
I will always charge my battery after each use and I will make sure it is charged prior to launching the boat. I always like to have a plan B.
 

Frank Acampora

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And then what do you do when you discharge the starting battery below the level necessary for starting the engine? Starting batteries are not deep cycle and will discharge rather quickly to a level below that needed to start the outboard. Running the outboard MAY help a little but the alternator simply puts out less than the trolling motor draws so eventually you will still discharge the starting battery. Unless your outboard has a separate electronic ignition not powered by the alternator and battery you are still up s^^ts creek without a paddle.

Much better idea is to buy another trolling battery.
 

alldodge

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[Paraphrasing your questions] can [a trolling motor be powered by the main engine battery] ?
Yes, there is no issue other then draining that battery as well

Do most of you carry jumper cables ?
Most don't, and I don't carry them either

As roffey mentioned, you don't want to drain either battery dead. A deep cycle battery can be drained lower then a standard start battery but not a much more. In a pinch you can disconnect and use jumper cables, or install a switch. Don't connect a good battery to one which has been drained low, you will just allow power from the good to go to the weak one
 

GA_Boater

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Problem is the OP is talking about an electric only lake. So using the gas motor is out of the question.

I would only use the starting battery as emergency back up to get you back on the trailer, not to keep fishing because of the potential of shortening battery life.

Best thing is to get another deep cycle battery to keep fishing and save the starting battery for the gas allowed lakes.
 

alldodge

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I understood the issue of an electric only lake, just trying to answer the OP question
 

bruceb58

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Using a starting battery to power a trolling motor will severely reduce the capacity of the battery after multiple uses. For example, if you discharge the battery down to around 20% capacity as little as 3 times, the battery would likely no longer hold much of a charge. You only want to use deep cycle batteries for a trolling motor.
 

robert graham

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About the jumper cable question, I do carry an inexpensive set of jumpers in my boat....for my own emergency use, but mostly to help other boaters out on the water with a weak, depleted or dead battery. If you can crank the dude up it could prevent you having to tow him back to the dock...and I've done plenty of both...not that I ever mind helping a fellow boater...
 

poconojoe

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As others have stated...only use your starting battery in a pinch. Just to get you back. Don't continue to fish.
As far as the jumper cables, I would be concerned about the jumper cables coming lose and shorting out. Big sparks with nowhere to run would not be a good thing. Your battery could even explode!
Personally, I would rather extend the trolling motor's wires so they will reach either battery. Much cleaner and safer way to go in my opinion.
 

Frank Acampora

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I missed the electric only lake! you can switch batteries BUT using jumper cables is not the best way because the good battery will be trying to recharge the drained battery. A better option is to either get a heavy duty battery switch and wire it in or disconnect the trolling motor from the discharged battery terminals and use longer wires. Jumper cables may supply the necessary amperage but they may also overheat at the trolling motor cable terminals.
 

fhhuber

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As a way to get to shore in a pinch... do what it takes.

As a general practice... no.

If its labeled as a marine battery its probably a hybrid between deep cycle and an engine starting battery. These are not best for deep cycle or starting engines... but its what we generally get.

A battery made specifically for starting engines would not do well with deep discharge from running a trolling motor.
 

smokeonthewater

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O/P you have shot yourself in the foot long before swapping batteries...

Unless you want to destroy your trolling motor battery you should NEVER discharge it below 50% capacity...

If you are at all in danger of fully discharging your battery then you probably need to go buy two much larger batteries... Possibly consider 12v golf cart batteries... They are some of the best

As for swapping your starting battery... The way to do it in a pinch is to unhook it and the t/m batts and put the start batt where the t/m batt goes n hook it up...

Jumper cables in a boat are risky at best.

Since it was mentioned, jumping another boat is also dangerous... Unlike cars boats are floating and easily knocked around in waves...

Maybe the other boat has a shorted wire, battery, or alternator... Maybe you catch them on fire, blow them up because their blower isn't working, or short out your own system...

Best to avoid jumper cables in a boat.
 

gm280

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If you plan on fishing the "Electric Only" lake, then I would swap out the cranking battery for a deep cycle trolling motor type for that possibility. However, If this is only preparing for an emergency situation, then swap the trolling battery if it runs down with the cranking and get back in. In serious cases, I would crank the engine to get in for help if the situation was serious and or life threatening. I would forego the jumper cables. They really don't transfer enough current to be worth carrying them on the boat. If this is a on going situation, I would install a battery switch with the proper cables runs so all you would have to do is turn the switch from #1 to #2 batteries. Way better then any jumper cable. JMHO!
 

roffey

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I would crank the engine to get in for help if the situation was serious and or life threatening.

in a life threatening situation,,, I would start up the gas motor and book it back to shore. Forget the electric motor, cables and batteries.
 

rallyart

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I carry 20' copper jumper cables in my 21' boat. I have used them once to help start another boat once in thee last eight years. I have some in each of my cars too. It just makes sense, to me, that such a simple thing can very quickly eliminate a problem for someone. If I can start a diesel pickup at - 40? by a boost from my minivan, I can start a boat in the summer that killed it's battery.

If you get jumper cables, for anything, the physical weight of the cable will give you a good indicator of it's value. Heavier is better. (Just for general information)
 

zpalffy

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And then what do you do when you discharge the starting battery below the level necessary for starting the engine? Starting batteries are not deep cycle and will discharge rather quickly to a level below that needed to start the outboard. Running the outboard MAY help a little but the alternator simply puts out less than the trolling motor draws so eventually you will still discharge the starting battery. Unless your outboard has a separate electronic ignition not powered by the alternator and battery you are still up s^^ts creek without a paddle.

Much better idea is to buy another trolling battery.

not true Frank I do have a paddle and what I am talking about here is on a electric lake only and using the other battery as a means to get back to the dock without the paddle.

The battery will not be getting charged from the alternator because I said that I would disconnet it
 

zpalffy

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Sep 29, 2015
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I carry 20' copper jumper cables in my 21' boat. I have used them once to help start another boat once in thee last eight years. I have some in each of my cars too. It just makes sense, to me, that such a simple thing can very quickly eliminate a problem for someone. If I can start a diesel pickup at - 40? by a boost from my minivan, I can start a boat in the summer that killed it's battery.

If you get jumper cables, for anything, the physical weight of the cable will give you a good indicator of it's value. Heavier is better. (Just for general information)


Thanks rallyart I am getting the cables and storing them on board better safe than sorry and I like having a plan B
 

Texasmark

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I only did it once, the first time out. I found the crank rope in the underside of the cowling and found out how to start an 85 hp 2 stroker by hand. Was amazed, it lit off the first pull but the the knot on the end of the rope was vicious as it made it's way out behind me. Ouch.
 
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roffey

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I only did it once, the first time out. I found the crank rope in the underside of the cowling and found out how to start an 85 hp 2 stroker by hand. Was amazed, it lit off the first pull but the the not on the end of the rope was vicious as it made it's way out behind me. Ouch.

hijacking this thread for a moment, when I was a teen the ski boat we used had a 115 merc. My friend pull started it. It was impressive. He was muscular to say the least and the event was talked about for years, so hats off to you.
 
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