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Thread: livescope sounder sizes

  1. #16

    Re: livescope sounder sizes

    Quote Originally Posted by Ronje1 View Post
    Don't bother with a 3rd battery. Assuming 1 for a electric and the other start/general use.

    A sealed/agm hybrid will do the job for you, Steve. Hybrids are a compromise (not really yr a.s. or yr elbow) and 80 amp job overkill. Lower yr sights a little.

    Unless u're in really cold country (-18 degrees C), don't bother looking at CCA figures. At more likely temps ( 0 degrees C or similar), the MCA figure (marine cranking amps) is the one to look for. It'll be higher than the CCA figures quoted for your choice.

    The sounders won't draw much current anyway and (as you say) a 50hp start won't load it. The sounders will only draw an amp or so each so u won't be deep-cycling anything.

    I would go marine though as the plates have different (more robust) construction to those of a normal crank battery.
    thanks for the reply coldest i go out in is 1-2 degrees in the mornings
    95svuhd draws 1.5 amps
    livescope somar module 2 amps
    gpsmap 8410 is 2 amps

    my last days fishing was 6 am to 12am then 2pm to 5pm thats 9 hours
    9vsv is always running and the live scope would used for 60-70% of that time so thats about 40 amp/hours all up for a days fishing, thats why i was considering a 80 amp battery

  2. #17

    Re: livescope sounder sizes

    Hi Steve

    I guess it boils down to what you actually need as opposed to what you are comfortable with.

    The most commonsense advice to the question "what size battery should I put in the boat" is: The biggest that will fit.

    That's a lot different to what do I need (what should work)

    Don't get deep cycle confused with cranking.

    The prime use of the battery you are looking for is for starting (cranking battery) so that you can get home. Its secondary use is to power a couple of devices (total 5 amps).

    Cranking batteries supply crank power to crank over yr o/board. They have thin plates to provide greater surface area in contact with the electrolyte THUS greater current available to crank yr motor.

    A deep cycle battery has thicker plates therefore less plate surface area so will provide a lower current for a longer period.

    Anything that tries to do both is simply a compromise. Manufacturers don't like calling their products compromises so they throw around terms like "hybrid" or "marine".


    To get things in perspective a bit, a large plastic bottle of milk is 3 litres. A cardboard bottle of milk is 1 litre. Look at the 1 litre cardboard carton and then look at yr 50hp motor. Bit of a difference in size.

    I've got a 3 litre diesel motor in 4WD ( 180 c inches). Should need a 180 CCA battery BUT its a diesel (high compression so needs more amps to crank it over).

    I think about the power plant for the car and a 3l bottle of milk at the same time and shake my head a bit. Wife's car (until recently) had a 245 c inch motor (about 4 litres/4000ccs). Her car needed a minimum of 245 CCA to start it.

    Basic rule of thumb for starting battery is 1 CCA per cubic inch for petrol motors.

    A 50 hp 4 stroke o/b is about 1000cc (1 litre). That's about 60 cubic inches.

    So u'd get away with a 60 CCA battery for starting yr petrol o/board. Not much is it?

    Throw in a few amps for the devices and a 100 CCA battery would suffice.

    Throw in some confidence/security/ insurance and you have 150 CCA.

    Would you be comfortable with a 150 CCA cranking battery?

    I wouldn't even though figures say its OK. Anyway, you'd be flat out finding a starting battery with low CCA figures like that.

    This'd do ya.

    r/c of 120 minutes and an MCA of 750 amps. Cranks o/boards up to 70 hp. Claims 65 AH ( a "pretend" deep cycle figure 'cos it ain't a deep cycle battery. Its a "pretend" one).

    The best figure to look at is the reserve capacity (in minutes). That's how long the battery will supply 25 amps before dropping to 10 volts (or so).

    If ya still feel insecure go a bit heftier.

    Claimed a mickey mouse 75 AH. 880 MCA and a RC of 150 minutes .

    Here's an Exide version of a similar battery

    Compare the AH figures.

    The Exide quotes 82 AH @ 20 hr rate.

    The Century just quotes 75 AH but no discharge rate. Could be @10 hr or @ 5hr in which case the quoted AH will be higher than the standard 20 hr rate (and bigger is better isn't it?). Bit misleading, eh.

    Battery manufacturing specs vary. The standard cranking current spec is quoted in cold cranking amps (CCA) and is worked out in cold climes like Europe and USA/Canada to handle bitterly cold temps of -18 degrees C. The battery voltage will drop to 7.2V

    after 30 seconds of cranking. Cold batteries don't perform well. If in lower temperatures and the battery is a 660 CCA, it'll deliver 660 amps for 30 secs before dropping to 7.2V.

    If u're in warmer climes like 0 degrees C, then the battery will deliver about 850 amps for 30 seconds before dropping to 7.2 V.

    Yr little low compression 50 hp motor (even if 4 stroke) won't draw anything like that to crank it over quickly.

    Also be wary of quoted AH figures. Only look for AH @ 20 hour rate. Some will quote high AH figures but the fine print (if any) will say @10hr or @5hr rates. Find the 20 hr rate, then you can compare apples with apples.

    Oils ain't oils Sol and batteries ain't batteries.

    Next time u're wondering about batteries look back at this thread.

  3. #18

    Re: livescope sounder sizes

  4. #19

    Re: livescope sounder sizes

    Be interested how it all goes Steve....


  5. #20

    Lightbulb Re: livescope sounder sizes

    Quote Originally Posted by stevej View Post
    Well done Steve. Let us know how you go as I am thinking of a live sight system in the future. SS

  6. #21

    Re: livescope sounder sizes


    planning to get a ram mount electric outboard stabiliser to support it while travelling
    Attached Images Attached Images

  7. #22

    Re: livescope sounder sizes

    for some reason that last photo keeps going sideways oh well if the boat ever ends up like that im in trouble lol

    plan to use it for freshwater yellow belly and cod fishing

    as per mooses posts i cant link the two sounders so eventually if i win lotto buy another 8410 or 12, the screen clarity is amazing
    also ended up getting one of these batteries to run it all

  8. #23

    Re: livescope sounder sizes

    Attachment 122769

    all installed
    this is how I plan to secure it while travelling
    I got a trolling motor ram mount support itís rock solid and doesnít move and Iíll add a strap over it when towing just in case something goes wrong

    only down side is the ball stays attached to the leg

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