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Lithium ion battery capacity calculations? Answered

     I'm working on a project that uses lithium ion batteries as the power source and cannot figure out how to calculate how long it will run for.  I have four 2.6Ah batteries connected in parallel, giving me a total of 10.4Ah of capacity.  They're lithium ion so the nominal voltage is 4.2v and the minimum I want to bring them to is 3v.  My project draws a constant 2.85W of power, regardless of the voltage put into it.  What I want to know is, is there any way to calculate or even just approximate how long these batteries will power my project before they run out (the voltage drops below 3v)?  The batteries are high quality, so the 2.6Ah rating is pretty reliable.  Let me know if there are more specifications needed or something.  


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5 years ago

Get the data sheet for your batteries. They contain curves showing voltage vs time. Without them it's just guessing.