The capacities of these batteries are measured in mAh which means milliamp Hour and is the unit that measures power over time . No , not quite . It measures total charge , regardless of time . the device that would tell me how long my battery can last is a Battery Voltage Indicator . No , not quite . The device is a State of Charge indicator , commonly known as fuel gauge . Voltage has got nothing to do with it . how the result in volts translates to how much power i have leftIt doesn ' t . There is no relationship between voltage and how much power i have left . There is a secondary , light , unreliable relationship between voltage and State of Charge , but you can ' t use it . How do i get the value of the I current ? is it the working current mentioned above ? Yes . How do i measure how much power my battery has leftYou don ' t measure power , you measure charge . how much longer i can use the Gimbal for ? Easy time remaining State of charge battery capacity load current . So , if the battery is full SoC 100 %, assuming a battery capacity of 3 . 5 Ah , and knowing that the load current is 0 . 35 A , thentime remaining 100 % 3 . 5 Ah 0 . 35 A 10 hoursCaveatIf your battery capacity is too small in your case , possibly less than 700 mAh , then other effects come into play , that limit your run time you ' ll have to stop discharging sooner , even though there is still charge in the battery , because you cannot extract that last bit of charge at that rate that current without damaging the cells in the battery . how much power my battery has leftThe reason that question cannot be answered is that batteries do not store power . They store charge , they store energy . They do not store power . Power depends on the load how much current it takes it depends on the type of cells used internal resistance it depends on temperature again , internal resistance it depends on the State of Charge . So , we do not look at a battery and say that it stores 1000 W of power . Instead , we look at a battery and say it stores 10 Ah of charge it stores 120 Wh of energy , some of which we can use to do work in our load , and some of which will be wasted in heat in the cells , depending on how fast we extract it .