Question: Can a car battery test good but be bad?

As long as battery voltage remains above 9.6 volts, the battery is considered “good.” But if it drops below 9.6 volts by the end of the test, the battery may be “bad,” or the battery may have to be recharged and retested if it was not fully charged prior to the test.

Can a car battery be bad even if it reads 12 volts?

If the battery cannot reach higher than 10.5 volts when being charged, then the battery has a dead cell. If the battery is fully charged (according to the battery charger) but the voltage is 12.5 or less, the battery is sulfated. … If your battery cannot even reach a full charge, consider it bad.

How can you tell if car battery needs replacing?

How to Know When it is Time to Replace Your Car Battery

  1. 1) Your Battery Struggles to Combat Seasonal Challenges. …
  2. 2) Your Car Has Been Sitting For Too Long. …
  3. 3) Your Vehicle Struggles When Starting. …
  4. 4) Your Battery Is Older and Triggers a Dashboard Light. …
  5. Alternative Starting and Battery Problems.
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Can a battery have good voltage and be bad?

Check the reading. A fully charged battery will typically display a voltmeter reading of about 12.6 to 12.8 volts. If your voltmeter is showing a voltage anywhere between 12.4 and 12.8, that means your battery is in good shape. Any voltage above 12.9 volts is a good indicator that your battery has excessive voltage.

Can a car battery have good voltage but low amps?

Cannot reach higher than 10.5 volts when being charged, then the battery has a dead cell. Fully charged (according to the battery charger) but the voltage is 12.4 or less, the battery is sulfated.



Can a battery have voltage but no AMPs?

State of Charge Voltage
25% 12.0
Discharged 0 – 11.9

What are the signs of a bad battery?

5 Unmistakable Signs Your Car Battery is Failing

  • Dim headlights. If your car battery is failing, it’s not going to be able to fully power your vehicle’s electrical components – including your headlights. …
  • Clicking sound when you turn the key. …
  • Slow crank. …
  • Needing to press on the gas pedal to start. …
  • Backfiring.

How many volts should a battery have?

Fully charged automotive batteries should measure at 12.6 volts or above. When the engine is running, this measurement should be 13.7 to 14.7 volts. If you don’t have a multimeter to tell you the voltage of your battery, you can do a test of your electrical system by starting the car and turning on the headlights.

How do you test a car battery to see if it is bad?

Connect the multimeter to the positive and negative battery terminals. If you don’t have a voltage of around 12.6 volts, you may have a bad battery. Now start the car, and look for a revised voltage over 10. If your voltage drops below 5 when the car is running, it is bad and should be replaced right away.

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How long can a car battery last without the engine on?

A new and fully car battery can stay for around two weeks without needing to be recharged from a generator. This battery will fully get discharged after approximately two to three months. If you leave the battery for roughly two and a half months, you will not be able to start the car engine.

How many volts should a car battery lose overnight?

The no load voltage should be around 12 V. The voltage will drop with the headlight load, but no more than maybe 1 V. If its a new battery with a good charging system 12.8 to 12.6 is what you should expect. The problem is in order to save fuel a lot of charging systems only charge your battery 80% to save fuel.

How do I know if my battery is bad or my alternator?

An illuminated dashboard light can indicate a problem with an automobile charging system. However, a very simple way to check if the alternator is working is to run the car and disconnect the positive terminal of the battery. If the vehicle stops running, then you probably have a bad alternator.

Help for your car