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Old 19 June 2012, 21:26   #1
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I need a battery for my Fish Finder???

Another question from a newbie...

I just bought a Humminbird PiranhaMAX 170. I thought the unit came with an internal battery that can be charged in my home outlet. As it turns out (and according to the manual), it must either be connected to a battery, or a fuse box. My SIB has neither.

My O/B has a 6 amp alternator.

My question(s):

Can I connect the Fish Finder directly to the outboard? Or do I have to get a battery for it?

If I do need a battery, are there really small ones out there that are safe to have on board, cheap, and will also provide enough power for the Fish Finder (and perhaps a light or two)?

Any help would be appreciated!

(Forgive my many questions. As much as I've done my homework before purchasing everything, many new questions came up right afterwards!)
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Old 19 June 2012, 23:46   #2
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A small sealed lead acid battery will be fine. Something like this
Sealed Lead Acid Battery 12V 20AH, 240wh (S)

Smaller would run your fish finder ok, but you'd have to manually recharge it at home as smaller won't accept 6 amps from your O/B. You could connect your fishfinder directly but then you wouldn't be able to drift with the engine off and have the fishfinder on.
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Old 20 June 2012, 00:34   #3
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Connecting directly to the OB will probably result in an overvolt condition. The output off the alternator is probably pretty high, and not really conditioned. A battery acts as a load and smooths and lowers the voltage from the alternator.

My SIB used a garden/tractor battery (about $39 at OSH) for starting (Honda 40 electric start) and small electronics. Never had a problem except when the battery died.

jky
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Old 20 June 2012, 09:25   #4
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Thanks for the suggestions. Do you think this battery would work:

Amazon.com: PowerStar AGM 12V 12AH RBC4 SEALED BATTERY: Health & Personal Care

Also, would I need a case for it, or is it safe to leave onboard exposed like it is?

Thanks again.
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Old 20 June 2012, 10:35   #5
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Quote:
Originally Posted by BuffsBoat View Post
Thanks for the suggestions. Do you think this battery would work:

Amazon.com: PowerStar AGM 12V 12AH RBC4 SEALED BATTERY: Health & Personal Care

Also, would I need a case for it, or is it safe to leave onboard exposed like it is?

Thanks again.
I reckon thats ideal . I'd not bother connecting to the engine (more complex and more to go wrong) . I used to use a battery like that to drive instruments in gliders (sailplanes in the US) for whole summers with only one or two charges needed a season.

So depening on your use I reckon you get a good few outings on one charge of that battery.

Some protection would be good for it -if only to protect the contacts from a wet environment , but no acid to spillout or gases to vent from them so no need to be as carefull as you would with lead acid batteries.
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Old 20 June 2012, 10:41   #6
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Try this

PeterM is right; you don't *need* to connect it to your engine if you don't mind charging before each outing. OTOH, it's 2 wires to the motor, plus a fuse for protection. Your choice.

Here is a box that will contain it and prevent accidental shorts across the terminals.

jky
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Old 20 June 2012, 16:12   #7
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try screw fix for a sealed lead acid battery, used one for my garmin fish finder 90 easily lasts all day, & recharge off boat, as for protection fitted mine into a tupper ware box to keep elements out put tail wires to connections through sealed lid and small plug on end to connect to fish finder/battery charger .works a treat.
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Old 25 June 2012, 16:31   #8
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The manual
http://www.google.co.uk/url?sa=t&rct...qBggrw&cad=rja
for your fishy finder doesn't state the current draw.

Google found this, a 12V 7ah battery

http://www.amazon.com/Humminbird-770.../dp/B000N314J0

This is the same battery that the Bravo HP pumps use.

Bigger is always better so this will be good. A 20ah will last ages and also over time when its capacity drops it will still work fine. Plus you can run lights and whatever off it. Its sealed so no leaks.

Linky as above

Simply charge by connecting it to 12V as you drive home. Check the voltage with a standard multimeter.

I charge mine (a 12ah) with a CTEK but I guess you don't want to spend 100 on a charger?

Trev I've found Screwfix are expensive nowadays, I used to order loads off them but not any more as other places are cheaper and no 50 min spend for free delivery. Not sure their free delivery covers the USA though.
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Old 25 June 2012, 17:32   #9
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AGM's have very specific charging requirements. Unless the engine has a voltage regulator, not just a rectifier, it should not be used to charge the battery. Most modern engines will have a regulator.

My boat has an electric starter, but I found leaving my Garmin GPS/Map/Sona unit on would kill the battery over a 3 day weekend, before I rigged up a charging system. You could easily charge the battery every night though.

I have a larger battery box I am no longer using. Like this one. NOCO Group U1 Battery Box: BatteryMart.com
I could box it, weigh it, and you can cut me a shipping tag? Since there is zero profit, that is my offer.
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Old 25 June 2012, 20:30   #10
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Peter - That is a very nice offer, and I appreciate it. But I just bought these items on Amazon...

Amazon.com: Moeller Power Plant Marine Battery Box with On-Touch Charge Indicator and 12-Volt Adapter (27, 30 and 31-Series Batteries): Sports & Outdoors
http://www.amazon.com/gp/product/B00...ls_o01_s00_i00

The battery box is a little more than I need for the fishfinder, but I can use the DC plug to charge the marine radio and my cell phone.

Hopefully I made the right choices.

Thanks again for the generous offer
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