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Old 10-16-2008, 05:31 PM
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Join Date: Jan 2007
Posts: 2,127
Default RE: Length of battery time on the water?

lknTP17 - 10/16/2008 11:11 AMIf you know the approximate current draw of the electronics you are using while not moving, you can pick a deep cycle battery based off of its Amp hour rating. Basically if you determine you are going to be drawing about 15 amps of current for a period of 2 hours, you would need at least a battery with a rating of 30 Ah (amps x hours). There really isn't a way to determine how long a cranking battery will last that I know of... however I'm pulling around 100 amps off a single group 24 700 CCA battery and I park for 4-5 hours at a time and have yet to drain my battery.
It is unrealistic to run a battery down to zero. With your example of 15 amps for 2 hours then you would want a battery with at least 70-80 amp hours in it. Considerably more if you are going to crank an engine with it after drawing it down.
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