mAh vs. Ah vs. Wh: Understanding Battery Capacity & Math
Buying a battery or power station can be confusing when one brand uses “mAh” and another uses “Wh.” Comparing them is like comparing apples to oranges unless you know the conversion math. This guide breaks down exactly what these terms mean and how to calculate your true runtime.
What is Battery Capacity?
Battery capacity represents the total amount of energy a battery can store. However, the industry uses different units depending on the application. Small electronics (phones) use mAh, automotive/solar batteries use Ah, and portable power stations use Wh.
Amp-Hours and Milliamp-Hours
Amp-Hours (Ah) measures how many amps a battery can deliver in one hour. Milliamp-hours (mAh) is simply a smaller unit of that same measurement (1/1000th).
- 1 Ah = 1,000 mAh
- 📱 A 5,000mAh phone battery is actually a 5Ah battery.
- 🔋 A 100Ah deep cycle battery is technically a 100,000mAh battery.
The Problem: Ah and mAh don’t tell you the total “fuel” in the tank unless you know the Voltage.
Watt-Hours (Wh): The Universal Standard
If you want to compare a 12V lithium battery to a 24V solar battery, you must use Watt-Hours. This is the unit of actual energy. It accounts for both capacity and electrical pressure (voltage).
| Battery Type | Ah Rating | Voltage | Total Capacity (Wh) |
|---|---|---|---|
| Standard Car Battery | 50 Ah | 12V | 600 Wh |
| LiFePO4 Solar Battery | 100 Ah | 12.8V | 1,280 Wh |
| Phone Power Bank | 20,000 mAh | 3.7V | 74 Wh |
Essential Measurement Tools
To verify if your batteries are actually performing to their rated capacity, you need to measure the draw in real-time.
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Smart Battery Monitor with Shunt: Provides live Ah and Wh countdowns for DIY systems.
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USB Power Meter: Perfect for testing the “mAh” of phone chargers and power banks.
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100Ah LiFePO4 Battery: The standard building block for 1,280Wh solar kits.
Battery Capacity FAQ
