Check my battery
Car Battery Voltage Checker
Enter your multimeter reading and we'll tell you how charged your battery is, and whether the problem is the battery or the charging system.
Last updated October 2026. By the editorial team.
Check your reading
Enter a reading to see the verdict.
How to use this tool
1. Turn the car off
For a resting test, leave it off for 12 hours.
2. Set your multimeter
Choose 20V DC on the dial.
3. Touch the terminals
Red probe to +, black probe to -.
4. Enter the reading
Type the number and read the verdict.
How the Voltage Test Works
A resting test is the most useful: leave the car off for 12 hours (or remove the surface charge by turning the headlights on for a minute, then off, and waiting), then measure across the terminals. A cranking test watches how far voltage sags when the starter draws current. A charging test checks what the alternator delivers with the engine running.
Resting thresholds come from OPTIMA Batteries' published guidance: about 12.6V or more is full, recharge below about 12.4V, and a healthy battery should not rest below about 12.0V. OPTIMA makes AGM batteries; we apply the same bands to flooded batteries until we add a flooded-battery maker source. Cranking (about 9.6V minimum) and charging (typically 13.7V to 14.7V) values are still starting points we are verifying. See how we calculate.
What to Do Next
- Low resting voltage: charge the battery fully, retest, and if it will not hold charge use the car battery replacement cost calculator.
- Poor cranking voltage: clean the terminals and try again. Our guide to cleaning battery corrosion helps.
- Charging voltage off: use the dead battery or alternator checker.
- Want the full procedure? Read how to test a car battery with a multimeter.
Frequently asked questions
What voltage should a healthy car battery read?
For a rested battery, about 12.6V or more is a full charge (OPTIMA gives 12.6V to 12.8V for its starting batteries). With the engine running, the charging system typically shows about 13.7V to 14.7V, though smart alternators can vary.
What does it mean if voltage drops while cranking?
Voltage should stay above about 9.6V while the engine cranks. A bigger drop points to a weak battery or poor connections.
Why do you not show a percentage?
We only show thresholds we can source. OPTIMA publishes about 12.6V to 12.8V for a full charge and advises recharging below 12.4V, so we show bands, not invented percentages.
Related tools and guides
Dead battery or alternator?
Decision-tree checker.
Learn moreHow to test a car battery
Multimeter guide.
Learn moreReplacement cost calculator
If it needs replacing.
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