Enter your Battery Voltage, Battery Type, and Temperature to find your battery's State of Charge — plus get a Temperature Compensated Voltage and a quick read on your Battery Condition, since heat and cold can throw off a raw voltage reading more than you'd expect.
State of Charge
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Temperature Compensated Voltage
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Battery Condition
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State of charge is the percentage of battery capacity that remains available. A 100% SOC means the battery is fully charged, while 0% means completely discharged.
Measure the open circuit voltage when the battery has been at rest for at least 2 hours without charging or discharging. Use a quality digital multimeter for accurate readings.
Battery voltage changes with temperature. Cold temperatures reduce voltage readings while warm temperatures increase them, so temperature compensation ensures accurate SOC calculations.
Each battery chemistry has different voltage curves. Lead acid batteries have different voltage-to-SOC relationships compared to lithium-ion or nickel-based batteries.
For lead acid batteries, recharge at 50% SOC to prevent damage. Lithium-ion batteries can be discharged deeper, typically to 20-30% SOC safely.
Voltage-based SOC calculations are reasonably accurate for rested batteries but can vary by ±5-10% depending on battery age, temperature, and load history.