mAh to kW Calculator
Convert battery capacity from milliamp-hours (mAh) to kilowatts (kW) using voltage and time. This is useful for estimating power output and sizing systems powered by batteries.
Understanding mAh to kW Conversion
Converting from milliamp-hours (mAh) to kilowatts (kW) involves converting a unit of battery capacity to a unit of power. These units measure different aspects of electricity:
- mAh: A unit of electric charge (capacity), typically used to rate batteries.
- kW: A unit of power, or the rate of energy usage or delivery.
Key Conversion Concept
The mAh rating tells you how much charge a battery holds. To convert it to kilowatts, you need to know:
- Voltage of the battery
- Time period (in hours) over which the power is delivered
Formula:
kW = (mAh × V) ÷ (1,000,000 × hours)
Step-by-Step Conversion
- Convert mAh to Ah: mAh ÷ 1000
- Energy in Wh = Ah × Voltage
- Power in W = Wh ÷ time (in hours)
- Convert W to kW: ÷ 1000
Example Calculations
- 5000 mAh at 5V over 2 hours:
Ah = 5000 ÷ 1000 = 5 Ah
Energy = 5 × 5 = 25 Wh
Power = 25 ÷ 2 = 12.5 W
kW = 12.5 ÷ 1000 = 0.0125 kW - 3000 mAh at 3.7V over 1 hour:
Energy = (3000 / 1000) × 3.7 = 11.1 Wh
Power = 11.1 ÷ 1 = 11.1 W → 0.0111 kW
Why Is This Useful?
This calculation is essential when sizing batteries for systems such as:
- Portable power stations
- Off-grid solar power systems
- Battery backups (UPS)
- RC drones, electric bikes, and more
Battery Types and Voltage
| Battery Type | Typical Voltage | Common Use |
|---|---|---|
| Li-ion (single cell) | 3.6 – 3.7V | Phones, laptops, drones |
| Lead-acid | 12V | Cars, UPS, solar systems |
| NiMH | 1.2V per cell | Rechargeable AA/AAA |
| LFP (LiFePO4) | 3.2V per cell | Solar, energy storage |
Understanding the Difference Between Energy and Power
Energy (Wh or kWh) represents the total work done or capacity. Power (W or kW) is the rate at which energy is delivered. A high-capacity battery may not deliver high power if current is limited.
Frequently Asked Questions
Is mAh a measure of energy?
No. It's a measure of charge (capacity). To get energy, you multiply by voltage.
Can I convert mAh to kWh directly?
Not directly — you must include voltage and time to make the conversion valid.
Why divide by 1,000,000 in the formula?
To convert from mAh × V (which gives milliwatt-hours) to kilowatts.
What if I don’t know the discharge time?
You can estimate power only if time is known. Otherwise, you’re calculating energy (Wh), not power.