A 12V battery's wattage depends on its amp-hour (Ah) rating
A 12-volt battery's power output is calculated by multiplying its voltage (12V) by its amp-hour capacity. For example, a 12V battery with 100Ah capacity delivers 1,200 watt-hours (Wh) of energy. This means it can theoretically supply 1,200 watts for one hour, or 600 watts for two hours.
Understanding battery capacity and wattage
- 12V 50Ah battery = 600Wh
- 12V 100Ah battery = 1,200Wh
- 12V 200Ah battery = 2,400Wh
The actual usable wattage varies based on discharge rates and battery chemistry. Lead-acid batteries typically deliver about 50% of their rated capacity at high discharge rates, while lithium batteries maintain more consistent output.
Comparing battery types and watt output
| Battery Type | Typical Capacity | Maximum Continuous Watts |
|---|---|---|
| Lead-acid | 50-200Ah | 300-1,500W |
| Lithium-ion | 50-200Ah | 500-3,000W |
| AGM | 50-200Ah | 400-1,800W |
Temperature, age, and discharge rate significantly affect a battery's watt output. A battery rated at 1,200Wh may only deliver 800-1,000Wh under real-world conditions.