Calculating current for electrolysis process

Is there a way to calculate the current during electrolysis of a dilute NaCl solution. 


I need to oxidise the chloride ions to create hypochlorite ($\ce{OCl-}$), so I was thinking of using 2 inert electrodes (Graphite) with an applied voltage slightly greater than 2.19 V. 


I want to calculate the current because I want to see how long I will have to run the electrolysis for to produce 0.5mg/L of ($\ce{OCl-}$), and how long the batteries will last. I was thinking of estimating the resistivity of the liquid but I'm not sure.


