# Battery Life Calculator

mAh

mAh

## Advanced:

mAh

### Output

The application of this calculator is when designing a microcontroller, IoT, edge, or other battery-powered project. It will help you determine how long the system can run off of a single battery before replacement or recharge and supports complex operating modes with different duty cycles and power consumption rates.

### Calculator 1: Basic Battery Life Calculator

The basic version of the calculator will take your project’s battery capacity and the device's current consumption and give an estimate of battery life.

#### Battery Life Equation:

To find battery lifetime, divide the battery capacity by the current draw of the load

$$B_l = \frac{B_c}{I_l}$$

Where:

• Bl = Battery lifetime in hours
• B= Battery capacity in mAh
• Il = Load device current draw in mA

### Calculator 2: Intermediate Battery Life Calculator for Systems with Two Operating Modes

Many battery-powered IoT sensor systems spend a small portion of their time in an active mode and the rest of their time in a low-power Sleep Mode. This calculator will take your project’s battery capacity and determine its lifetime based on the following parameters:

1. The amount of time the device is running
2. How much current is consumed when it's running
3. The amount of time the device spends in Sleep Mode
4. How much current it consumes in Sleep Mode

#### The Intermediate Battery Life Equation:

To find battery lifetime, divide the battery capacity by the average device current consumption over time. The average is the amount of current consumed when awake, scaled by the ratio of time that the device is awake, plus the amount of current consumed when in Sleep Mode, scaled by the ratio of time that the device is in Sleep Mode.

$$B_l = \frac{B_c}{\frac{I_a t_a}{t_a + t_s}+{\frac{I_s t_s}{t_a+t_s}}}$$

Where:

• Bl = Battery lifetime in hours
• Bc= Battery capacity in mAh
• Ia = Device current consumption when awake in mA
• Is = Device current consumption when in Sleep Mode in mA
• ta = Time spent awake in seconds (per cycle)
• ts = Time spent in Sleep Mode in seconds (per cycle)

### Calculator 3: Advanced Battery Life Calculator for Systems with Four Operating Modes

For battery-powered IoT sensor systems that transmit data wirelessly, there are often four unique operating modes: Sleep, Data Collection, Data Processing, and Data Transmission. The system will cycle through each of these modes with each mode requiring a different amount of power.

This calculator will take your project’s battery capacity and determine its lifetime based on the following parameters:

1. The amount of time the device spends in Sleep Mode
2. How much current it consumes in Sleep Mode
3. The amount of time the device spends transmitting data
4. How much current it consumes when transmitting data
5. The amount of time the device spends collecting data
6. How much current it consumes when collecting data
7. The amount of time the device spends processing data
8. How much current it consumes when processing data

#### The Advanced Battery Life Equation:

To find battery lifetime, divide the battery capacity by the average device current consumption over time. You can then break it down into where:

• The average is the sum of the amount of current consumed when collecting data, scaled by the ratio of time that the device is collecting data
• The amount of current consumed when transmitting data, scaled by the ratio of time that the device is transmitting data
• The amount of current consumed when processing data, scaled by the ratio of time that the device is processing data
• The amount of current consumed when in Sleep Mode, scaled by the ratio of time that the device is in Sleep Mode

$$B_l = \frac{B_c}{\frac{I_s t_s} {t_s+t_t+t_c+t_p} + \frac{I_t t_t}{t_s+t_t+t_c+t_p} + \frac{I_c t_c}{t_s+t_t+t_c+t_p}+\frac{I_p t_p}{t_s+t_t+t_c+t_p}}$$

Where:

• Bl = Battery lifetime in hours
• Bc= Battery capacity in mAh
• Is = Device current consumption when in Sleep Mode in mA
• It = Device current consumption when transmitting data in mA
• Ic = Device current consumption when collecting data in mA
• Ip = Device current consumption when processing data in mA
• ts = Time spent in Sleep Mode in seconds (per cycle)
• tt = Time spent transmitting data in seconds (per cycle)
• tc = Time spent collecting data in seconds (per cycle)
• tp = Time spent processing data in seconds (per cycle)

### Further Reading:

Textbook—Battery Ratings

Batteries Worksheet

0 Comments