Fishing Tackle

Author Topic: 12 V 6 Amp charging step down to 12 V 1 Amp?  (Read 2013 times)


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12 V 6 Amp charging step down to 12 V 1 Amp?
« on: Apr 21, 2020, 12:46 PM »
The Gist of it:

Anyone know how to step 12 V 6 amps down to 12 V 1 amp? 

The background:

Looking for some advice.  I have a 15 ft aluminum boat with a large, heavy, 27 amphour deep cycle battery.  My Honda 20 hp 4 stroke charges that when running at 12 V at 6 amps.  The deep cycle battery is only a few years old and already getting tired out.  I also run a Garmin echo map 54 dv of the battery, and have running lights and a bilge pump that I almost never use hooked up.  I trailer and store the boat in my garage when not in use.  Each night I put the big battery on a smart charger which brings it back to full, then maintains it. 

Looking to lighten up the whole system.  My kids are getting to be teenagers, and putting on the pounds. 

I just bought a 54 amp hour Dakota lithium battery that will arrive in May.  I plan to put this up front with the trolling motor to redistribute some weight.  Also, this new battery cannot take the 12 v, 6 amp charging system from the honda (according to the tech guy I talked to at Dakota Lithium, and I believe him).  I plan to charge this with the included special lithium charger each night when I get home. 

Now I'd like to run a small sealed lead acid battery in the back for the fish finder, lights, pump and have it charged with the honda output when running.  These little batteries, the ones that come with portable fish finders take a charge at 1 amp.  I'm sort of handy with wiring, having a multi meter and know how to measure voltage vs amps.  But not very handy in looking for marine quality transformers and such online. 


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Re: 12 V 6 Amp charging step down to 12 V 1 Amp?
« Reply #1 on: Apr 21, 2020, 01:36 PM »
Hook up everything on the boat to the cranking battery EXCEPT the trolling motor.  You will have to charge that deep cycle battery separate, but the cranking battery will be re-charged every time you start the motor.

Mac Attack

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Re: 12 V 6 Amp charging step down to 12 V 1 Amp?
« Reply #2 on: Apr 21, 2020, 02:14 PM »

The voltage regulator in the Honda will back off the charge when your main battery gets close to being charged.
Just like in your car or any other vehicle.
They need to do this or they would simply "cook" your battery.
The Honda puts out a max of 6A.
But it's not always putting that out.
Only as needed.
It will throttle back as the battery gets charged.
And of course at low rpm when the alternator isn't putting out full amps.

And charge the new lithium separately as needed each time.


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Re: 12 V 6 Amp charging step down to 12 V 1 Amp?
« Reply #3 on: Apr 21, 2020, 08:19 PM »
Ah, great advice, thanks!


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