I have an SLA battery, at say 10 Amp-Hours, connected to 3 high power motors. Each motor can draw up to 10 Amps each (worst case / max power). Using `Q = It` as an approximation, I see that I get 1200 seconds of usage. (Q = 3600\*10, I = 30, t in seconds)

For my application, what circuit can I built/add on to measure (estimate) the charge remaining? Right now it's literally just SLA battery --> motor controllers --> motors, with an Arduino connecting to the motor controllers. 

I was wondering if something like this: <https://www.sparkfun.com/products/11005> could connect to the battery leads, the other end to Arduino, and then I sample the current every few milliseconds and "subtract" the charges from my total of 10 Ah. E.g. `charge_used = sample_period * current_measured;` followed by `charge_remaining -= charge_used;`. 

Are there better ways of measuring the remaining battery capacity? Is my approach even feasible? 

Cheers