# Battery Life Online Calculator

Below is battery life calculator.The voltage regulator in between the battery and the device is optional. Note that your battery voltage(such as 3.7) must exceed the device required voltage and so you can choose number of batteries in series to exceed the voltage required and use a voltage regulator such as LM7805 IC. See as an example the tutorial Calculating Li-Ion Battery Life for Your 5V Devices.

# Battery Life Calculator

mAh

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## Online Battery Life Time Calculator

Our online battery life calculator helps you estimate how long your devices can run when powered by lithium-ion batteries. By inputting the battery specifications, device power consumption, and voltage regulation efficiency, you can quickly determine the expected runtime. This tool is ideal for planning your projects and ensuring your devices have sufficient power, regardless of their operating voltage.

### Equations Used

1. Total Energy Stored in Batteries (Wh): $\text{Total Energy (Wh)} = \text{Voltage} \times \text{Capacity} \times \text{Number of Batteries}$
2. Effective Energy Available (Wh): $\text{Effective Energy (Wh)} = \text{Total Energy (Wh)} \times \text{Efficiency of Voltage Regulator}$
3. Power Consumption of Device (W): $\text{Power Consumption (W)} = \text{Device Voltage} \times \text{Device Current}$
4. Runtime (Hours): $\text{Runtime (Hours)} = \frac{\text{Effective Energy (Wh)}}{\text{Power Consumption (W)}}$

### Example Calculation

Scenario: Estimating the runtime of an Arduino Uno powered by two ICR 18650 3800mAh 3.7V lithium-ion batteries using an LM7805 voltage regulator.

1. Battery Configuration:

• Two batteries in series: Total Voltage = 3.7V * 2 = 7.4V
• Capacity remains the same at 3800mAh (3.8Ah)
2. Total Energy Stored in the Batteries:

$\text{Total Energy} = 3.7V \times 3.8Ah \times 2 = 28.12 \text{Wh}$
3. Adjust for Efficiency of the Voltage Regulator:

• LM7805 efficiency is approximately 60%
$\text{Effective Energy Available} = 28.12 \text{Wh} \times 0.60 = 16.872 \text{Wh}$
4. Power Consumption of the Arduino Uno:

• The device consumes 50mA at 5V
$\text{Power Consumption} = 5V \times 0.05A = 0.25W$
5. Calculate Runtime:

$\text{Runtime} = \frac{16.872 \text{Wh}}{0.25 \text{W}} = 67.488 \text{hours}$

Based on these calculations, the two 3.7V 3800mAh lithium-ion batteries can power the Arduino Uno for approximately 67.488 hours, assuming a constant power draw of 50mA and considering the efficiency of the voltage regulator.