When you’re shopping for batteries, you’ll often see their capacity listed in watt hours (Wh) and milliamp hours (mAh). Watt hours measure the amount of energy a battery can provide over time, while milliamp hours measure its electrical charge capacity.
This article will explain how to easily convert watt hours to milliamp hours. Knowing how to do this conversion is essential for comparing different batteries and picking the right power source for your needs.
Keep in mind that the voltage of the battery is a key factor in this conversion. We’ll show you how voltage plays a role in the conversion process.
What are Watt Hours (Wh)?
Watt hours (Wh) represent a unit of energy. One watt hour equals the amount of energy delivered by one watt of power over a period of one hour. For example, a 50 Wh battery could deliver 50 watts for one hour.
Watt hours are commonly used to measure how much energy a battery can store. You’ll often see Wh listed on things like laptop batteries and portable power stations.
Watt hours are also used to measure how much energy appliances use. For instance, you might look at the watt hours consumed by a refrigerator to estimate your energy bill.
What are Milliampere Hours (mAh)?
Milliampere hours (mAh) are a unit of electric charge. A milliampere is one-thousandth of an ampere.
The mAh rating tells you how much electric charge a battery can hold at a specific voltage. For example, a 5000 mAh battery can (theoretically) deliver 5000 milliamperes (or 5 amperes) of current for one hour.
Knowing the mAh of a battery allows you to estimate how long it will last before needing to be recharged.
You’ll often see mAh used to describe the capacity of small batteries, like the ones in your smartphone or portable charger.
Why Voltage Matters
Voltage is like the “push” behind the electricity flowing through a circuit. It’s the electrical potential difference, or the force that moves the current.
Voltage plays a big role in figuring out a battery’s capacity and converting between watt-hours (Wh) and milliamp-hours (mAh). To convert Wh to mAh, you must know the battery’s voltage (V), because the formula is mAh = (Wh 1000) / V.
Here are some common battery voltages:
- Lithium-ion batteries: 3.6V to 3.7V
- Alkaline batteries: 1.5V
- Lead-acid batteries: 12V
How to convert watt hours to milliampere hours (Wh to mAh)
Converting watt hours to milliampere hours is relatively straightforward, as long as you know the formula.
The conversion formula
Here’s the formula:
mAh = (Wh / V) 1000
In this formula:
- mAh = Milliampere hours, which is what you’re trying to find
- Wh = Watt hours, which should be listed on the battery or device
- V = Voltage, which is also usually listed on the battery or device
It’s important to find the correct voltage, because using the wrong number in the calculation will give you the wrong answer.
Step-by-step conversion example
Let’s say you want to convert a 10 Wh battery at 5V to mAh. Here’s how you’d do it:
mAh = (10 Wh / 5V) 1000 = 2000 mAh
In other words, you divide the watt hours by the voltage, and then multiply by 1000.
Practical applications
This conversion is useful for comparing batteries, managing energy use, and determining whether a particular battery will work with a particular device.
Converting Kilowatt Hours to Milliampere Hours (kWh to mAh)
You can convert kilowatt hours (kWh) to milliampere hours (mAh) using this formula:
mAh = (kWh / V) 1,000,000
First, it’s helpful to know the relationship between kWh and Wh: 1 kWh = 1000 Wh. Kilowatt hours and watt hours both measure energy, but kilowatt hours represent a larger quantity.
Here’s an example of converting kWh to mAh:
Let’s convert 0.01 kWh at 12V to mAh:
mAh = (0.01 kWh / 12V) 1,000,000 = 833.33 mAh
Conversion Charts for Quick Reference
Sometimes you just need a quick estimate. That’s where conversion charts come in handy. These charts let you quickly look up the milliamp hours (mAh) equivalent of a given number of watt hours (Wh) at a specific voltage.
Here are some examples. Please note that these charts are approximate and for quick reference only. For precise calculations, use the formula above or an online calculator.
Watt Hours to Milliamp Hours at 12V
[Insert Chart Here]
Watt Hours to Milliamp Hours at 24V
[Insert Chart Here]
Watt Hours to Milliamp Hours at 36V
[Insert Chart Here]
Watt Hours to Milliamp Hours at 48V
[Insert Chart Here]
If you prefer, you can also find a Wh to mAh conversion calculator online.
When would I need to convert Wh to mAh?
You might need to make this conversion when evaluating different power sources. Here are a few common examples:
- Power Banks: To determine how well a power bank will charge your devices and how long the charge will last.
- Electric Vehicles (EVs): To understand the battery capacity of an EV and how far you can drive on a single charge.
- Solar Generators: To figure out how much energy a solar generator can store, especially when using it for off-grid power.
In Summary
If you work with batteries, it’s important to know how to convert watt-hours into milliamp-hours.
To make the conversion, you have to know the voltage of the battery and apply the correct formula. Knowing how to convert Wh to mAh has many practical applications, whether you’re choosing the right battery for your device or comparing power capacities.