Understanding Ah to kWh Conversion
Converting Ampere-hours (Ah) to Kilowatt-hours (kWh) is a crucial calculation when dealing with batteries, solar energy systems, and electric vehicles. While both units relate to electricity, they measure different things. This calculator helps you bridge that gap to determine total energy capacity.
What are Ah and kWh?
- Ampere-hour (Ah): This is a unit of electric charge. It tells you how much current a battery can provide over one hour. For example, a 100Ah battery could theoretically provide 100 Amps for one hour, or 1 Amp for 100 hours. It measures capacity, but not total energy.
- Kilowatt-hour (kWh): This is a unit of energy. It measures how much power (in kilowatts) is used over a period of time (hours). This is the unit most commonly used on electric bills and to describe the actual energy storage of large batteries (like in electric cars).
The Conversion Formula
Because Ah only measures charge, you cannot convert it to energy (kWh) without knowing the electrical pressure, or Voltage (V), of the system. The relationship is defined by the following formula:
(Ampere-hours × Voltage) / 1000 = Kilowatt-hours
Or simply:
(Ah × V) / 1000 = kWh
First, multiplying Ah by V gives you Watt-hours (Wh). Since there are 1,000 Watt-hours in one Kilowatt-hour, you divide the result by 1,000 to get the final kWh figure.
Real-World Calculation Examples
Here are a few common scenarios where you might need to use this calculation:
Example 1: Standard Car Battery
A typical car battery might be rated at 12 Volts and 60 Ampere-hours. To find its energy capacity in kWh:
- (60 Ah × 12 V) / 1000 = 0.72 kWh
Example 2: Deep Cycle Marine/RV Battery
A large deep-cycle battery used in an RV solar setup might be rated at 12V and 200Ah.
- (200 Ah × 12 V) / 1000 = 2.4 kWh
Example 3: E-Bike Battery
An electric bicycle battery usually operates at a higher voltage, for example, 36V or 48V. Let's take a 48V, 15Ah battery:
- (15 Ah × 48 V) / 1000 = 0.72 kWh
Notice that the e-bike battery has the same energy (0.72 kWh) as the car battery in Example 1, even though its Ah rating (15Ah) is much lower than the car battery's (60Ah). This highlights why voltage is critical when determining actual energy storage.