Tech Papers and Guides

Calculate battery life

Use this as generic calculator to calculate battery life and capacity:

C = Battery capacity (mAh)

BL= Battery life (years)

Is = Current when device is in sleep mode (mA)

Itx = Current when device is in transmit mode (mA)

Irx = Current when device is in Receive mode (mA)

Imeas = Current when device is in measurement mode (mA) [it depends on technology used and application]

Ttx = Amount of time that device is in Transmit (TX) mode (ms)

Trx = Amount of time that device is in Receive (RX) mode (ms)

Tmeas = Amount of time that device is in measurement mode (ms) [depends on technology used and application]

Ta = Amount of time that device is active (ms)

Ta = Ttx+ Trx +Tmeas

U = Usable capacity after taking into account self-discharge (%)

N = Number of times the device will be active per day

cU = Capacity after taking into account discharge rate (mAh) = C*(U/100)

T = Milliseconds per hour = 3600000

cA = Active capacity usage per day = N*(Ttx*Itx + Trx*Irx + Tmeas*Imeas)

cS = Sleep capacity usage per day = Is*( 24-((Ttx + Trx + Tmeas)*N/T) )

cT = Total capacity consumed per day = cA+cS

Battery Life (days) = (cU/cT)/24

Battery Life (years) = days/365.24