Battery state
Screen charge level, age and behavior after a jump start.
Check battery voltageA guided multimeter test
Battery, starter or alternator?
Enter your actual voltage readings. StartVitals combines all three stages and tells you what to test next—without guessing which part to replace.
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Example readingsCombined screen
12.18V resting
BatteryLow charge
CrankingNeeds retest
Charging14.2 V seen
One engine, three stages
Stop replacing parts from one voltage number
A resting battery, a battery under starter load and a running charging system answer different questions. The tool keeps those questions separate, then combines the evidence.
Cranking performance
Use the minimum voltage during crank to spot excessive 12-volt sag.
Battery or starter?Charging support
Compare running and loaded voltage with the rested baseline.
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How it works
Four readings. One useful next step.
Safety first
Stop for battery damage, hybrid/EV systems or unsafe access.
Engine off
Measure rested battery voltage directly at the terminals.
Cranking
Capture the minimum voltage during a normal start attempt.
Engine running
Record charging voltage, then repeat with electrical loads.
Quick voltage checker
What does this one reading mean?
Useful for orientation—not a complete diagnosis.
Frequently asked questions
Can a multimeter tell me if my battery is bad?
It can show state of charge and voltage behavior, but voltage alone cannot measure the battery's remaining CCA or capacity. Use StartVitals as a screen, then confirm a weak result with a proper load or conductance test.
What voltage should a car battery show?
A rested, fully charged conventional 12-volt lead-acid battery commonly reads around 12.6 volts or a little higher. Battery chemistry, temperature, recent charging and vehicle activity can change the reading.
Does 14 volts mean my alternator is good?
It supports that the alternator was charging at that moment, but it does not prove current output under load, diode condition or correct behavior at all temperatures. Smart-charging vehicles can also vary voltage intentionally.
Will StartVitals tell me which part to replace?
No. It identifies which stage deserves the next test and explicitly avoids a replacement verdict when voltage cannot separate the battery, cables and starter.
Does the test work on hybrids or EVs?
This version is for conventional 12-volt systems. It stops rather than guide users around hybrid or EV high-voltage equipment. Follow the owner’s manual for an accessible auxiliary battery.
Important safety limit
StartVitals never asks you to disconnect a battery while the engine is running, short terminals, probe orange high-voltage cables or place loose leads near belts and fans. Stop if the battery is swollen, leaking, cracked, frozen, unusually hot or strongly odorous. Read the full safety checklist.