powering fish-finder on a small boat

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nevadan

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I have a 13' Smokercraft Alaskan. Until now it has had no electrical system, the OB is manual start. I bought a fish-finder and am having trouble figuring out a way to power it. I found a small 12V battery that should do the trick, but my OB puts out to much current to charge the battery. I don't want to haul around a full sized battery just to power the fish-finder. Advice please!
 
Silvertip

Silvertip

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Re: powering fish-finder on a small boat

Most auto stores have 1.5 amp battery maintainers which are nothing more than small battery chargers. A motorcycle battery or a garden tractor battery will work just fine. A garden tractor battery can be found at Lowes or Home Depot for about $25 and will run the locator for many days. Motorcycle batteries tend to be much more expensive and have much less capacity.
 
109jb

109jb

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The garden tractor battery is a good suggestion but i thought i would throwbout what a friend did. he had an old rechargeable drill (12v) and rigged it up to his fishfinder in his small boat. He can then just take the battery pack in and use the factory drill charger to charge it. I guess it works at least for a couple hours. I'd probably go with the garden tractor, or motorcycle battery myself. I always seem to have one lying around the shop anyway.
 
halfmoa

halfmoa

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Re: powering fish-finder on a small boat

You can buy an 8 cell battery case from Radio Shack on the cheap. Use rechargeable batteries.

If it was me I'd go the garder tractor battery and charger route. That way you've got 12V (13.8~whatever) for any other accessories you may want to use.
 
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Rick.

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Re: powering fish-finder on a small boat

I have a portable hummin bird 160. I comes with a small 12volt battery and the battery lasts a very very long time. I've used it four consecutive long days of fishing and it still was running fine. I'm sure they must sell replacements for it and that is the battery I would choose.
 
Silvertip

Silvertip

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Re: powering fish-finder on a small boat

Those batteries are typically 7 Ahr and run about $20. They need a charger that may cost $10 - $15.00. Garden tractor batteries are small and have great deal more capacity and can be charged with any standard charger. Yes -- they are a tad bigger but still much smaller than a car battery. As Tim Allen would say -- "More Power".
 
fucawi

fucawi

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Re: powering fish-finder on a small boat

my outboard puts out too much current to charge the battery ....rubbish....if we are talking a small say 7 Ah lead acid battery all you need to be concerned about is the output voltage from your outboard not above 14,4v for a sealed battery ....your quoted output from the outboard is the maximum current it will give and lead acid batteries are self regulating for charge current,
Make sure the output from your outboard is 12v DC not the AC often supplied for running lights .....
 
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gonzo891

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Aug 9, 2011
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Re: powering fish-finder on a small boat

i use a battery from my drill. i used two spade connecters and opened them up so they fit on the prongs on the battery. mines a 12v dewalt and it lasts all day charge it when i get home and its good to go nexted trip. ive been out 8 hours and lasted the whole time. plus its light and about the size of an apple
 
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nevadan

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Re: powering fish-finder on a small boat

I don't think it's rubbish in this case. The battery (a 7 Ah burglar alarm model) states that the input current should not exceed 1.75 Amps, and my outboard puts out 5 Amps. Am I missing something?
 
Silvertip

Silvertip

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Re: powering fish-finder on a small boat

nevadan said:
I don't think it's rubbish in this case. The battery (a 7 Ah burglar alarm model) states that the input current should not exceed 1.75 Amps, and my outboard puts out 5 Amps. Am I missing something?
Click to expand...

Yes -- you are missing something (or more accurately -- misunderstanding something). When a manufacturer states the alternator charging system has 7.5 amp output (in your case), that means the absolute maximum "current" that alternator can supply is 7.5 amps. It does not mean that's what is being "forced" iinto the battery. The battery will "accept" only what it is capable of accepting. A bad battery for example will accept no charge whatsoever regardless what the charging system output is. The issue with charging a battery is that the "charge rate" should not exceed roughly 20% of the battery capacity. So -- in your case 20% or 7 amps is 1.4 amps but the battery manufacturer says 1.75 amps is maximum.
 
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