# Battery question



## azevedo16 (Aug 18, 2010)

I have a battery that is a 7.5AH/20HR.My lights with the 75 watt bulbs draw 6 amps.Question is how long it would run 1 light.I am rigging my Kayak with 2 lights and am trying to get away from toting a car battery around.


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## cone (Sep 15, 2011)

You have a battery rated at 7.5Ah at a 20 hour rate. What does that mean? It means it will give a true 7.5AH at a 375ma rate (a little over 1/3 amp.) If the light draws more it wont put out as many AH. For example a 1 amp draw on that battery wont last 7.5 hours it will be less. Maybe 3hrs (just a guess.) There are formulas to figure it out but I don't know them by heart. 
Most batteries if not marked are figured on a 20hr rate, but some may be figured on other rates such as a 10hr rate. Bob


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## cone (Sep 15, 2011)

More info: 
http://www.smartgauge.co.uk/peukert2.html
http://www.smartgauge.co.uk/peukert_depth.html


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