How to Read Battery Specs: mAh, Voltage, Watt-Hours Explained
When shopping for a battery pack, you’ll often see technical terms like mAh, voltage (V), and watt-hours (Wh). These numbers aren’t just marketing jargon—they’re key to understanding how much power you’re getting and whether it’s the right fit for your device.
In this guide, we’ll break down these essential battery specifications so you can make smarter decisions when choosing your next power source.
What Does mAh Mean?
mAh stands for milliamp-hours and it’s a measure of electric charge—essentially, how much power a battery can deliver over time.
In Simple Terms:
- A higher mAh rating means more capacity.
- For example, a 10,000mAh battery can deliver 1,000 milliamps for 10 hours, or 2,000 milliamps for 5 hours.
Why It Matters:
- It tells you how many times you can charge a device before the battery pack itself needs recharging.
- A phone with a 3,000mAh battery can be fully charged about 3 times with a 10,000mAh pack (factoring in some power loss).
What Is Voltage (V)?
Voltage measures the electrical potential or pressure that pushes electricity through a circuit. Most consumer devices use voltages between 3.7V and 20V, depending on the application.
Common Voltages:
- 3.7V – Typical lithium-ion cell voltage.
- 5V – Standard for USB charging.
- 9V–20V – Often used for fast charging or high-drain devices (like laptops or power tools).
Why It Matters:
- The right voltage ensures your device gets enough power without damage.
- A mismatch in voltage can lead to slower charging or even device malfunction.
What Are Watt-Hours (Wh)?
Watt-hours (Wh) represent the total amount of energy stored in the battery. It’s calculated using this formula:
Watt-hours (Wh) = mAh × Voltage ÷ 1000
Example:
A 10,000mAh battery at 3.7V:
10,000 × 3.7 ÷ 1000 = 37 Wh
Why It Matters:
- Watt-hours give you a real-world estimate of how long the battery can power a device.
- Airlines often limit battery packs above 100Wh in carry-on luggage—so this number is crucial for travel.
How All 3 Specs Work Together
| Spec | What It Tells You | Why It’s Important |
|---|---|---|
| mAh | Capacity (how long) | More mAh = more charges |
| Voltage | Power pressure (how fast) | Higher voltage = faster or more efficient power transfer |
| Wh | Total energy (capacity × voltage) | Used for comparing batteries across different voltages |
To choose the right battery pack:
- Check your device's voltage and power input.
- Look for high mAh for long-lasting power.
- Use Wh to compare energy across different batteries.
Bonus Tip: Efficiency Isn’t 100%
Not all the energy in a battery pack reaches your device—some is lost due to:
- Heat
- Voltage conversion
- Cable resistance
You typically get around 85–90% of the advertised mAh in real-world use. Keep this in mind when calculating how many full charges you’ll get.
Final Thoughts
Understanding mAh, voltage, and watt-hours turns battery shopping from guesswork into smart decision-making. Whether you're powering a smartphone, drone, camera, or camping gear, reading battery specs helps ensure your devices get the right amount of power, safely and efficiently.
At ElektroEdge, all our product listings include detailed battery specs—because knowledge is power (literally).
