# What size battery?



## Cracker (Mar 31, 2008)

I finally found a suitable boat today, and am going to go pay for it tomorrow, and bring it home. I've been out of the boating scene for a while, and this is my first outboard.

It needs a battery for electric start and hummingbird (no TM yet). A mechanic I know said to get just a small 12 volt battery like a lawn mower would use to start the engine.

My question is this... What size (cranking amps, I guess) do I need?
What else do I need to know and/or consider?

This is a '99 2 stroke Evinrude. There is no battery in in now, we started it with a battery from another boat, so I have no idea what it has been running with. 

Thanks for you help


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## Cracker (Mar 31, 2008)

should have mentioned it is a 15 hp engine

Thanks


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## Captain Ahab (Apr 1, 2008)

I woudl not waste the time with the lawn tractor battery - you can run this with any car type battery (Starting Battery or "SLI" Starting, Lighting, Ignition) just fine, but a deep cycle marine battery will always work better, especially if you might run a trolling motor or pump in the future. Get a deep cycle 


Found this that answers lots of battery questions:

https://marine-electronics.net/techarticle/battery_faq/b_faq.htm#7.7

Remember, deep cycle batteries will not have as many cranking amps Starting batteries are usually rated at "CCA", or cold cranking amps, or "MCA", Marine cranking amps - the same as "CA" True deep cycle batteries generally are not rated this way.

*
NOW TO ANSWER YOUR QUESTION*

Mercury recommends that you use 465 Marine Cranking Amps (MCA) or 350 Cold Cranking Amps (CCA) to start their 2 -stroke engines less then 75 hp. For a 15 hp engine you can go less then that


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## Cracker (Apr 1, 2008)

Thanks for the information, Esquired.

Next question, though, is... if the deep cycle starts the outboard, and little else right now ( except the depth finder ), wouldn't the alternator of the engine be sending a constant re-charge?? That is to say -- I thought it was best to run a deep cycle battery down instead of recharging constantly. I admit I may be wrong, but this is what I have always understood... that a battery (deep cycle) would become "trained" to NOT hold a charge.

I know that the answer may be in the link you offered, but I didn't have the patience to decipher it.

Thanks again


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## redbug (Apr 1, 2008)

go with a 24 group it is a deep cycle starting battery and has good cca and a fair amount of reserve Min's


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## Jim (Apr 1, 2008)

Cracker said:


> Thanks for the information, Esquired.
> 
> Next question, though, is... if the deep cycle starts the outboard, and little else right now ( except the depth finder ), wouldn't the alternator of the engine be sending a constant re-charge?? That is to say -- I thought it was best to run a deep cycle battery down instead of recharging constantly. I admit I may be wrong, but this is what I have always understood... that a battery (deep cycle) would become "trained" to NOT hold a charge.
> 
> ...



I don't think it needs to be run down to empty. Once charged it will always stay "mostly" charged and just be topped off. The humminbird will draw nothing for power.


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## BlueWaterLED (Apr 1, 2008)

Cracker said:


> Thanks for the information, Esquired.
> 
> Next question, though, is... if the deep cycle starts the outboard, and little else right now ( except the depth finder ), wouldn't the alternator of the engine be sending a constant re-charge?? That is to say -- I thought it was best to run a deep cycle battery down instead of recharging constantly. I admit I may be wrong, but this is what I have always understood... that a battery (deep cycle) would become "trained" to NOT hold a charge.
> 
> ...


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## Cracker (Apr 3, 2008)

Group 24 deep cycle it shall be 

Thanks everyone!


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## Popeye (Apr 4, 2008)

Deep cycle doesn't mean it should be cycled long and hard, just that it can handle being disharged deeper than a regular cranking battery. Also, Lead acid batteries don't develop a "memory" like Ni-Cad batteries do.


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