NEVER Buy a Car Battery Before Checking These 3 Numbers, by Walt Harlan's Garage on YouTube. 13 min 14 s.
- Video length
- 13 min 14 s
- Time to do it
- 15 minutes
- Difficulty
- Easy
- Steps
- 8
What you need
Steps
Open your owner's manual and note the group size, cold cranking amps and reserve capacity your car needs. The old battery's label shows the same figures if the manual is missing.
Find the date code on the case or label. It is often a letter for the month plus a number for the year, so skip any battery that has sat on the shelf for more than about six months.
Compare cold cranking amps. Buy a battery with a CCA rating equal to or higher than the original spec, never lower, or cold starts will strain the starter.
Check the reserve capacity figure in minutes. A higher number keeps lights, wipers and electronics running longer if the alternator fails, which matters on modern cars.
Decide between AGM and a standard flooded battery. Cars with start-stop systems or heavy electronics usually need AGM, so match what the car came with.
Test your current battery before spending money. With the engine off, touch the multimeter probes to the terminals and read the voltage: about 12.6 volts is full, 12.4 is half, below 12.2 is low.
Clean any white corrosion with a paste of baking soda and water, then rinse and dry. Wear safety glasses and gloves, and always disconnect the negative cable first.
Check the voltage again after the car has sat overnight. A battery that drops fast under load is failing even if it started fine that morning.
Tips and common mistakes
Write the date code on your calendar so you know when the warranty and the battery's useful life run out.
A battery that passes a voltage test can still fail suddenly in cold weather, so test it before winter rather than after a no-start.
Keep the receipt and note the warranty length, since a longer warranty is often worth more than a famous brand name.
Never lean over a battery while it is charging and keep sparks and metal tools away from both terminals.
Questions
What voltage should a healthy car battery show?
A rested, fully charged battery reads about 12.6 volts with the engine off. Around 12.4 volts means roughly half charged, and anything under 12.2 volts needs charging or replacing.
Can I use a higher CCA battery than my car came with?
Yes, going higher is safe and gives extra cold-start margin. Going lower than the original rating is what causes slow cranking and starter strain.
How old is too old for a new battery on the shelf?
Look for stock under about six months old by the date code. A battery that has sat for a year or more has already lost part of its life before you install it.
This guide was drafted from the video's details and general task knowledge. It has not been checked against the full video. Check the video and relevant product instructions before following a procedure. Report a correction.
