Trolling Motor and Battery Help

[dtag31]

Hi Guys, 

I really want to upgrade to an 80# thrust trolling motor, but I am using a 17ft aluminum boat that happens to be designed fairly poorly for the batteries and 6 gallon gas tank. Right now I am running a 45# motor and if there is a brisk wind, I'm basically sitting still, I can't fish into the wind (and I hate when it's at my back). The nice thing is, I only have a 20hp motor and have had zero issues cranking that tiny motor 5 times a day while using the deep cycle as my trolling motor battery, it pulls double duty. 

 

My huge concern, if I go to a 24 volt system, from what I've read, I need to go to a separate battery as my cranking motor. I'm concerned about the space, the money for 3 batteries, and the weight. 

 

Can anyone offer some insight as to what 2 batteries would make a good pair for an 80# Fortrex and then, what I could potentially use as my cranking/fish finder battery that can hopefully be smaller than the group 27 battery I am running now (for trolling and cranking). I really want to invest in the minn kota fortrex, but I am seriously stressing this battery situation. 

 

Thank you!

Dillon

[WRB]

20 hp 2 cycle OB is usually easy to pull start. 2 ea 12v batteries are wired in series to provide 24v to the TM. You can add a 40 amp battery switch to 1 battery for cranking, switch it to 2 batteries for the TM. Remembering to switch back and forth may become a problem. What are you doing for any sonar units that run on 12v?  A smaller size gr 24 deep cycle battery dedicated for cranking and electronics and 2 gr 27 or 29 deep cycle batteries for the TM should work for a light weight aluminum boat. Put the 6 gallon gas tank in the middle of the boat, 3 batteries in the rear.

Tom

[BassNJake]

I've got a 16 and half foot Aluminum Crestliner with a 25 horse motor.

It's got a Maxxum 101lb thrust 36 volt trolling motor.

I run 3 size 31 optimas for the trolling motor and have a size 27 for starting battery/electronics.

 

The boat is like a tank not gonna break any speed records but I can stand on the trolling motor all day without worry.

 

I've never wished to have a smaller trolling motor but know plenty of guys that want more trolling motor than they currently have.

[Ratherbfishing]

I can't say anything more knowledgeable guys won't tell you but I have heard (and I believe it's true) that it taxes a deep cycle battery quite a lot to use it as a cranking battery.  And running down a cranking battery by using it as a trolling motor battery is also bad for it.  It's better to have separate types of batteries for each application.  I have a 17 foot with a 12 volt trolling motor (probably about a 40 # thrust, though I'm not sure) and if the wind is so strong that I can't use it, I simply don't go.  It's no funny anyway.  If you want considerably more power, you're probably need to go to a 24 volt system.  

[ratman]

should you also run some new heavier gauge wire?

[TheRodFather]

I have a 70# 24v Powerdrive, I am using 3 Walmart Everstart batteries.  Interestingly, the Everstarts are built by the same company that builds Interstate batteries, which are the gold standard for traditional chemistry batts.   I bought all three of them new about 3-4 years ago, right around 100 bucks apiece, and they are all going strong.

 

I use a Noco 3 bank charger, and the cranking battery always goes green (fullly charged) within 8 hours, the deep cycles seem to take longer to get to green, overnight usually.  But I have never, and I mean never, come even close to running the batteries down past 50% (as shown by the batt checker on the TM).  I have no doubt I could fish for two days on one charge.  I built my boat for the susquehanna river (lots of current).  Now that I'm in NC on lakes, I have way more TM than I'll ever need.

 

Always keep the batts fully charged, if possible, charge as soon as you get home.  This will keep the batteries lasting longer.  The TM instructions will help you decide if your wire is sufficient or if you should upgrade.  Your breaker may need upsized too.

[Further North]

7 hours ago, BassNJake said:

I've got a 16 and half foot Aluminum Crestliner with a 25 horse motor.

It's got a Maxxum 101lb thrust 36 volt trolling motor.

I run 3 size 31 optimas for the trolling motor and have a size 27 for starting battery/electronics.

 

The boat is like a tank not gonna break any speed records but I can stand on the trolling motor all day without worry.

 

I've never wished to have a smaller trolling motor but know plenty of guys that want more trolling motor than they currently have.

My kind of set up!

 

I've never heard anyone say their trolling motor had too much power.

[WRB]

Wire? Are you asking about the wire to operate the TM 17' from the battery? I dought the aluminum boat is pre-wired,if it is probably using 8 gage marine multi copper strand wire. Changing to 6 gage will reduce resistance and DC voltage drop at full power, otherwise a minimal for a 24v wire length.

This boat probably doesn't weigh more then 1,200 pounds with fully loaded. 80 lb thrust 24v TM at 1/2 power is more then enough to control a light weight 17' aluminum boat.

Based on 20 hp OB with 6 gallon tank doesn't sound like a pre wired bass boat to me.

Tom

[Way2slow]

I'm just gonna make one comment.  Running a deep cycle battery for a cranking battery on a small motor is not a problem, it does not harm the battery in any way.  

Where the problem comes in using a deep cycle as a cranking battery is with the big motors that require heavy cranking amps.  A deep cycle will not produce a large amount of cranking amps, it's not designed to do that, and you can have cranking problems with large motor.  The voltage drop can be too much to power the ecu and other things to make it fire.  Matter of fact, a "true" deep cycle does not even have a CCA/MCA rating on them.

[OnthePotomac]

Sorry sir, but my Deka 27 deep cycle marine is labeled 575CCA@0 degrees and 720MCA@32 degrees and runs my 55lb MG, digital, variable speed all day on my 17'6" G3 and.that is on a very windy tidal Potomac river. That motor set on "10" will flat move out.  I could not see a need for a bigger TM and more batteries.  I use an Interstate for a starting battery.

[Tim Kelly]

1 hour ago, OnthePotomac said:

Sorry sir, but my Deka 27 deep cycle marine is labeled 575CCA@0 degrees and 720MCA@32 degrees and runs my 55lb MG, digital, variable speed all day on my 17'6" G3 and.that is on a very windy tidal Potomac river. That motor set on "10" will flat move out.  I could not see a need for a bigger TM and more batteries.  I use an Interstate for a starting battery.

One size 27 battery to a 55lb TM on a 17' boat in current? Do you only fish a 3 hours at a time? I used to have a size 31 on a 55lb on my 12ft boat and fished a very slow moving river. I was really noticing the battery drop after 4 or 5 hours. 

[Jig Man]

1 hour ago, OnthePotomac said:

Sorry sir, but my Deka 27 deep cycle marine is labeled 575CCA@0 degrees and 720MCA@32 degrees and runs my 55lb MG, digital, variable speed all day on my 17'6" G3 and.that is on a very windy tidal Potomac river. That motor set on "10" will flat move out.  I could not see a need for a bigger TM and more batteries.  I use an Interstate for a starting battery.

Is it a deep cycle or multi purpose battery?

[OnthePotomac]

Deep cycle as I described.

I am on the river for 4-5 hours in an outing. My TM battery is charged on a 10amp charger immediately after each outing, in addition to using a pulse desulfinater and the MG TM is digital, which makes a big difference in battery draw.