Car battery voltage chart
A healthy 12V car battery at rest reads 12.6 to 12.7V when full, about 12.4V at 75 percent, 12.2V at 50 percent and 12.0V at 25 percent. Below about 12.0V it may not start the car in cold weather.
1.25A
A mid-range pick from the gear this chart is about. More across the price range below the chart.
Resting open-circuit voltage for a flooded lead-acid battery near 77 F, measured after the battery has sat for a few hours with no load or charge. AGM batteries read slightly higher. Run your own numbers in the battery charge time calculator.
| Resting voltage | State of charge | What it means |
|---|---|---|
| 12.7V | 100% | Full |
| 12.6V | 95% | Full |
| 12.5V | 85% | Fine; recharge soon if it keeps dropping |
| 12.4V | 75% | Fine; recharge soon if it keeps dropping |
| 12.3V | 62% | Charge it; a common parking-mode cutoff zone |
| 12.2V | 50% | Charge it; a common parking-mode cutoff zone |
| 12.1V | 37% | Low; may not start in the cold |
| 12.0V | 25% | Low; may not start in the cold |
| 11.9V | 12% | Flat; charge now, risk of sulfation |
| 11.8V | 5% | Flat; charge now, risk of sulfation |
| 11.6V | 0% | Flat; charge now, risk of sulfation |
Chargers and maintainers to bring it back
An even spread across the price range. Prices change often.
Frequently asked questions
Where do the numbers in this chart come from?
Resting open-circuit voltage for a flooded lead-acid battery near 77 F, measured after the battery has sat for a few hours with no load or charge. AGM batteries read slightly higher. They are calculated, not measured on any one product, so real results vary with the specific model, its settings and its condition. The battery charge time calculator runs the same formula on your own inputs.