How long could I run a trolling motor off the starting battery?

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ZmOz

Captain
Joined
Aug 13, 2003
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After I broke down in the lake last month I found that it is nearly impossible to paddle my boat. If someone wouldn't have been there to tow me in I probably would have had to sleep on the lake. :rolleyes: Anyway, I think I want to get a cheap used trolling motor just for emergencies. I know normally you aren't suppost to use those with your cranking battery, but about how far do you think I could get in my 16' CV-16 with a (cheap automotive) starting battery?
 
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John Nutter

Seaman Apprentice
Joined
Oct 3, 2003
Messages
35
Re: How long could I run a trolling motor off the starting battery?

When you can buy a deep cycle marine battery for somewhere between $50 and $70. and you are planning ahead for trouble why would you even think about or use the word CHEAP.If looking for equiptment to make your life safer and better you should never ever,even let cheap be a part of this desision
 
A

airman

Petty Officer 1st Class
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Aug 9, 2003
Messages
332
Re: How long could I run a trolling motor off the starting battery?

I'd go with a 2hp outboard. Figure out a way to pump the gas from the main tank, even the primer bulb is good enough in a pinch. Carry enough oil to mix the gas if the main engine is a 4-stroke. That's what I do anyways, except that the get-home is a 15. A starter battery won't get you far, especially if you ran it dead first trying to start the engine. It also won't help if the motor quit from a bad alternator.
 
Z

ZmOz

Captain
Joined
Aug 13, 2003
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3,949
Re: How long could I run a trolling motor off the starting battery?

$50-70 is not cheap for a battery when I've already got one. ;) I allways carry one of those portable jump start batteries with me, in my boat and in my truck. It's enough to start the engine on it's own, but I know it wouldn't run a trolling motor for long. I'd rather go with an electric motor rather than a small outboard, because I could store the electric inside the boat somewhere when it isn't needed, and one of the reasons I might need it is running out of gas. :D (although I allways carry an extra gallon with me for backup!)
 
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Paul Moir

Admiral
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Nov 5, 2002
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6,847
Re: How long could I run a trolling motor off the starting battery?

RC (reserve capacity) is how long a battery will supply 25 amps at 80degF without the cell voltage dropping below 1.75v. 10.5v, or 1.75v per cell, is essentially discharged for a l2v battery.<br />So, AH = RC / 2.4.<br />If you have, say, a 80 minute RC battery, and you hook it to a trolling motor that draws 30A, your battery will last for (80min / 2.4) / 30A, or 1.1 hours before the battery is completely flat.<br />Discharging the battery by more than 50% damages a starting battery badly. Discharging it at all seems to hurt them, so keep it topped up.
 
C

cobra 3.0

Lieutenant Commander
Joined
Jul 31, 2003
Messages
1,797
Re: How long could I run a trolling motor off the starting battery?

I have a 28 amp trolling motor. I use a very large deep cycle battery for marine/rv use. Its has plenty of cranking power and it lasts 3-4 hours full out and probably 20-24 hours on low power. <br /><br />On a heavy boat in lots of chop, a gas powered motor is far superior. My little Evinrude 4 hp is just the ticket.
 
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the hangman

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Aug 27, 2003
Messages
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Re: How long could I run a trolling motor off the starting battery?

ZmOz - I had motor trouble a while back - so this summer I bought a trolling motor and made a temporary bracket. I added a second battery later in the season. I feel much safer knowing I have it on board.<br /> I have a 17 foot fiberglass boat with a 85 Hp outboard. The trolling motor is a 36 pound thrust with a 36" shaft - that was the largest that would fit in my in-floor ski storage locker. I made a bracket to mount it on the transom. I bought a medium size battery - don't know the size off hand. It pushed the boat pretty well in calm water - but I wish it could be a little larger.<br /><br />Jeff
 
J

John Nutter

Seaman Apprentice
Joined
Oct 3, 2003
Messages
35
Re: How long could I run a trolling motor off the starting battery?

Hey Hangman..You can go to a larger size motor if you will shorten the shaft down to the 36" that will fit into your box.This is not a big job to do.But it gives you the option of more power
 
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the hangman

Cadet
Joined
Aug 27, 2003
Messages
24
Re: How long could I run a trolling motor off the starting battery?

Reelman - actually it is the length of the motor housing that is the problem - the ski locker is something like 14" wide x 8 feet long
 
R

ri01rod

Recruit
Joined
Nov 10, 2003
Messages
3
Re: How long could I run a trolling motor off the starting battery?

A starting battery and deep cycle are 2 different units. A deep cycle is designed to be charged and dischareged several times. A regular battery is not. Keep using a standard starting battery and you will get to replace it and buy a deep cycle very soon. <br />Shold buy a seperate deep cycle for this use. Also charge it right away after use.
 
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