One Battery

Discussion in 'Power it up with Electronics' started by MariettaMike, Sep 19, 2012.

  1. MariettaMike

    MariettaMike Wish'n I was Fish'n!

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    Anybody else running a 55# 12V trolling motor off of one dual purpose 27M battery that is also used for cranking?

    I have been doing this for half day trips and the Yami 90 cranks right up. Since the trolling motor "motor" is bigger than my starter motor and is fed by a #10 wire that is smaller than the #6 going to my starter I assume that if the trolling motor will run, then the starter will start. ???
     
  2. Dillusion

    Dillusion devilray snob

    I have used only one 12v deep cycle battery for my last two skiffs and it has always worked just fine. And they both have lights, TM, bilge, and outboard starter.
     

  3. firecat1981

    firecat1981 BBA Counselor

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    I use one battery too, but I can always pull start mine with a rope I keep with me when the battery dies. The trolling motor may look bigger, but the starter motor is stronger and requires more amps to start up, hence the higher gauge wire. Your TM probably uses about 50amps at the highest setting, your starter might draw several hundred for just a second or 2. So just cause your TM is still going, even on the highest speed, your outboard may not crank. You could just hook up a battery gauge and save the guess work.
     
  4. MariettaMike

    MariettaMike Wish'n I was Fish'n!

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    Thanks for the responses. Now I know I'm not alone.

    There is just so little space in a flats boat that it seems worth the risk to go with one battery and not have to pole an extra 50 lbs of lead around.

    I don't run a bait or live well nor stereo and disco ball.

    My Minn Kota TM has a battery strength indicator on it and I'm guessing it is really just a voltmeter without numbers. I could use my digital multimeter to measure and write the scale on the TM with a Sharpie.

    To evaluate the starting risk I'm going to have to try and pull start my 90 with the rope. I've hand cranked a 300 Lycoming on an airboat a couple times before so I'm optimistic.

    If that doesn't work I've got a SeaTow membership, but I'll need to read the fine print to see what a jump start would cost me.

    Thanks again for the responses.
     
  5. firecat1981

    firecat1981 BBA Counselor

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    Livewell pumps and lights don't draw much at all, especially if the lights are LEDs like mine. My pumps are 500gph and only draw 1.5amps. When I went fishing in marco I had the pump running for 3 days straight and never had an issue starting my motor.
    On the flip side once after running just the trolling motor for for 5 hours on lower settings without starting up the motor the battery was drained to where the outboard barely cranked up, but the indicator on my TM said I had half a battery left. The battery level indicators on the TM's are less then accurate at times so be aware.

    Keep in mind you have a way to charge your battery some when on the water. If you have ran your TM for a few hours and the fishing dies off just crank up your motor for a little while as you wait for the tide to turn or while having a snack in between spots. At idle my 20hp puts out 6amps and I believe 10amps at speed, your 90hp should easily be double that.
     
  6. Dillusion

    Dillusion devilray snob

    Thats a good point too, which reminds me; I dont even know if the rectifier on my merc is working lol
     
  7. fsae99

    fsae99 I Love microskiff.com!

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    I run 2 batteries for 3 reasons.

    First, RF interference from TM being connected to same bat as FF/CP. With any of the digital TM controllers the possibility of RFI problems goes way up.

    Second, I never want to worry about battery condition. I'd hate to shorten my fishing time because of it, not have VHF working, and it is a very bad feeling to be 12 miles from sighting land and the motor not start when the key is turned.

    Third, I do not have a chase (at least that I could find) from the front to the CC.

    I'd really try pull starting your motor in the driveway. Out on the water is not the place to find out you can not.
     
  8. cutrunner

    cutrunner Cert. Yamaha technician

    Ive pull started a 200 merc v6 (2 stroke).
    It actually wasnt that bad.
    If you got a friend with you that can work the throttle accordingly that helps alot.

    Which reminds me that i need to make a rooe for my motor for a backup.
     
  9. Morgan_Duett

    Morgan_Duett Well-Known Member

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    mike/matty when yall refer to using 1 battery, what group size is it? also what are some good marine batteries for cranking, bilge, nag, 55# tm? firecat you also mentioned that the motor can charge the battery some? i have a 2000 merc 20hp will it charge my battery?
     
  10. Dillusion

    Dillusion devilray snob

    I have ran, and am running, a single battery setup with various sizes.

    If you are running a trolling motor I would go with at minimum a deep cycle battery or group 27 deep cycle.

    If you are not running a TM you can get away with a single odyssey pc680 or pc925.

    Currently I'm running all my accessories plus a merc 40 2 stroke off of an odyssey pc680 but I don't use trolling motors...

    If you are running a TM on a single battery setup I would only do it if you are comfortable and know how to pull start your motor just in case. And also know when to drop using the trolling motor, for example knowing to only use it for an hour or so before stopping so you don't drain the battery.
     
  11. Morgan_Duett

    Morgan_Duett Well-Known Member

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    Thanks for the reply matty, I can start my motor just fine with the rope. I've been using a group 24 deep cycle 12v for starting,tm it lasts like half a day if that?! Does my merc 20hp charge the batt at all?
     
  12. Dillusion

    Dillusion devilray snob

    All outboards with a rectifier should charge the battery while running, check your outboard specs. it to my knowledge it should...