Understanding Battery Energy
When comparing batteries, the "Ah" or "mAh" rating only tells half the story. To know how much "work" a battery can do, you must calculate the Watt-hours (Wh). Our Pro Battery Capacity Calculator provides this critical conversion and helps you understand the efficiency of your power storage.
Ah vs. Wh: Why Voltage Matters
A 100Ah battery at 12V and a 100Ah battery at 24V have the same "Amp-hour" rating, but the 24V battery stores twice as much energy.
- 12V × 100Ah = 1,200 Wh
- 24V × 100Ah = 2,400 Wh This is why electric vehicles and solar arrays use higher voltages—it allows them to store more energy in the same footprint.
Calculating Energy Density (Wh/kg)
Energy density is a measure of how much energy a battery stores relative to its weight. This is the "Holy Grail" of battery technology.
- Lead-Acid: Low density (30-50 Wh/kg). Heavy and bulky.
- Lithium-Ion: High density (150-250 Wh/kg). Light and compact. Our calculator helps you compare different battery chemistries to see which provides the best "power-to-weight" ratio for your project.
Applications for This Tool
- Solar Sizing: Calculate the total Wh capacity needed to run your home through the night.
- Drone Building: Find the best balance between battery capacity (Wh) and flight weight (kg).
- EV Conversions: Estimate the total pack size needed to achieve a specific range.