Maintenance procedure · Written to ASD-STE100 Issue 9 · Formatted to ANSI Z535

Choosing a Replacement Vehicle Battery: How to Read the Old Battery's Label Before You Buy

Passenger cars and light trucks — match the group size, the terminal layout, the hold-down and the cold cranking amps rating, and confirm the chemistry, before a new battery leaves the shelf
ApplicabilityPassenger cars and light trucks with a 12-volt lead-acid starting battery. Does not cover hybrid or electric vehicle high-voltage battery packs, motorcycles, or heavy trucks with a different electrical system.
Task time10 min to 22 min editorial estimate, not a measurement
PersonnelOne
Revisionv1 · 2026-08-03
BEFORE YOU BEGIN

Before you begin. This procedure is general reference information, not professional advice. Equipment varies by manufacturer, model, and year. Always follow the documentation supplied with your equipment — where it differs from this page, follow the manufacturer. Verify that you have the tools, the working conditions, and the ability to do this task safely. If anything is unclear, if the equipment is damaged, or if the task exceeds your experience, stop and use a qualified professional. You are responsible for your own safety and for the outcome. This site accepts no liability for any loss, damage, or injury arising from the use of this information.

Specifications marked unverified could not be traced to a manufacturer source. Do not rely on them — obtain the value from your equipment documentation.

Summary

A replacement car battery has to match the vehicle in five separate ways at once, and the sticker on the case spells out most of them plainly once you know where to look. The case has to be the right group size so it fits the tray and its cables reach the posts. The positive and negative posts have to sit on the correct sides, and the hold-down bracket has to match the mounting hardware. The cold cranking amps rating has to meet or beat what the vehicle maker specifies. The chemistry — flooded, enhanced flooded, or absorbed glass mat — has to be the one the vehicle's charging system was designed around, which matters more than it used to now that many newer vehicles require AGM.

This page shows you how to read every one of those markings off the battery that is already in the vehicle, and how to check them against the owner's manual before you go shopping, so the battery you bring home is the right one the first time. It does not cover disconnecting the old battery or fitting the new one — those are separate jobs with their own hazards. If a reading is missing or does not match the manual, the safest step is to ask the vehicle maker or a parts store rather than guess.

Necessary equipment

ItemNote
Flashlight optionalA flashlight helps you read the label in a dark engine bay.
Pen and paperPen and paper let you record every marking on the label.
Vehicle owner's manualThe manual gives the group size, the rating and the chemistry for the vehicle.
Eye protectionEye protection guards your eyes from acid on a damaged battery.
Phone with a camera optionalA photograph is a backup record of every marking on the label.

Prepare the vehicle

Estimated 1 min to 2 min

  1. Park the vehicle on level ground.
    <1m
  2. Stop the engine.
    <1m
  3. Set the parking brake.
    <1m
WARNING

DO NOT OPEN THE HOOD WHILE THE ENGINE RUNS.
A part in the engine can injure you.

  1. Open the hood.
    • The vehicle documentation gives the position of the hood release.
    <1m
  2. Put on eye protection.
    <1m

Find the battery and the label

Estimated 1 min to 3 min

WARNING

DO NOT TOUCH CORROSION ON THE BATTERY.
Corrosion on a lead-acid battery can carry sulfuric acid. Sulfuric acid can burn your skin and your eyes.

WARNING

DO NOT BRING A FLAME OR A LIT CIGARETTE NEAR THE BATTERY.
A lead-acid battery can vent hydrogen gas. Hydrogen gas can explode.

  1. Find the battery in the engine bay.
    • The vehicle documentation gives the position of the battery.
    • A few vehicles have the battery in the trunk or under a seat.
    <1m
  2. If the engine bay is dark, use a flashlight.
    <1m
  3. Find the printed label on the top of the battery.
    • A worn label can be on the side of the case.
    <1m

Read the case size and the terminal layout

Estimated 2 min to 3 min

NOTEThis code covers the case size and the terminal position.
Battery group size for this vehicle
Unverified — do not rely on this value
CONSULT THE VEHICLE OWNER'S MANUAL, A PARTS STORE LOOKUP, OR THE CODE ON THE ORIGINAL BATTERY.

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

Position of the positive terminal for this vehicle
Unverified — do not rely on this value
CONSULT THE ORIGINAL BATTERY OR THE VEHICLE OWNER'S MANUAL.

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

Hold-down shape for this vehicle
Unverified — do not rely on this value
MATCH THE SHAPE ON THE ORIGINAL BATTERY, OR ASK THE PARTS STORE.

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

  1. Find the group size code on the label.
    • This code comes from Battery Council International.
    • The code shows the length, the width, the height and the terminal position.
    <1m
  2. Write the group size code on paper.
    <1m
WARNING

DO NOT LET A METAL OBJECT TOUCH BOTH TERMINALS AT THE SAME TIME.
A short circuit at the terminals can burn you.

  1. Find the terminal with the plus sign.
    • This terminal is the positive terminal.
    • The other terminal is the negative terminal.
    <1m
  2. Write the position of the positive terminal on paper.
    <1m
  3. Look at the bracket that holds the battery in the tray.
    • This bracket is the hold-down.
    • A hold-down keeps the battery still.
    <1m
  4. Write the shape of the hold-down on paper.
    <1m

Read the cold cranking amps rating and the chemistry

Estimated 1 min to 2 min

NOTEThe rating and the chemistry must match the vehicle maker's requirement.
Minimum cold cranking amps rating for this vehicle
Unverified — do not rely on this value
CONSULT THE VEHICLE OWNER'S MANUAL. NEVER BUY A BATTERY BELOW THIS RATING.

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

Battery chemistry required for this vehicle
Unverified — do not rely on this value
CONSULT THE VEHICLE OWNER'S MANUAL.

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

  1. Find the cold cranking amps rating on the label.
    • The rating often has the letters CCA next to a number.
    <1m
  2. Write the cold cranking amps rating on paper.
    <1m
  3. Find the chemistry marking on the label.
    • AGM is the short form of absorbed glass mat.
    • EFB is the short form of enhanced flooded battery.
    • A label with no letters often shows a flooded battery.
    <1m
  4. Write the chemistry of the battery on paper.
    <1m

Compare the figures with the vehicle documentation

Estimated 4 min to 11 min

NOTECompare every figure with the owner's manual before you buy a battery.
  1. Open the vehicle owner's manual.
    <1m
  2. Find the battery information in the manual.
    • Some manuals give this information in a section on specifications.
    • Some manuals give this information in a supplement.
    1m
  3. Compare the group size code with the code in the manual.
    <1m
NOTICE

DO NOT BUY A BATTERY WITH A LOWER RATING THAN THE VEHICLE MAKER STATES.
A weak battery can fail to start the engine in cold weather.

  1. Compare the cold cranking amps rating with the minimum rating in the manual.
    <1m
NOTICE

DO NOT BUY A FLOODED BATTERY IF THE VEHICLE NEEDS AN ABSORBED GLASS MAT BATTERY.
The wrong chemistry can cause a fault in the charging system.

  1. Compare the chemistry with the chemistry in the manual.
    <1m
  2. If the manual gives no figure, speak to the vehicle maker or a parts store.
    1m

Record the information before you shop

Estimated 1 min

  1. Take a photograph of the label with a phone.
    • A photograph keeps every marking together.
    <1m
  2. Close the hood.
    <1m
  3. Keep the paper record with the vehicle documentation.
    <1m
  4. Take the record to the store when you buy the battery.
    <1m

Terminology

This page uses one term for each item and holds it throughout, as ASD-STE100 requires. Equipment sellers and other guides use the names below for the same parts.

battery group size
Also called: battery size, what size battery do I need, BCI group number, group size chart
cold cranking amps
Also called: CCA, cranking amps, cold cranking amp rating, how many amps does my battery need
absorbed glass mat battery
Also called: AGM battery, AGM, sealed battery, maintenance free battery, VRLA battery
flooded battery
Also called: wet cell battery, standard battery, conventional battery, regular battery
enhanced flooded battery
Also called: EFB battery, EFB, start-stop battery
hold-down
Also called: battery clamp, battery bracket, battery strap, the thing that holds the battery down
lead-acid battery
Also called: car battery, starter battery, starting battery, 12 volt battery, auto battery

When to use a professional

Speak to the vehicle maker or a parts store if a reading does not match the owner's manual. Speak to the vehicle maker if the manual gives no figure for the battery. This page gives no instruction for the removal of the old battery or the installation of the new battery. A parts store or a qualified technician can do this work. Speak to a qualified technician about any extra step your vehicle needs after you fit a new battery.

Common questions

What battery does my car take?

The exact answer is on the battery that is already under your hood, not in a universal chart. Read the group size code, the terminal layout, the hold-down shape, the cold cranking amps rating, and the chemistry (flooded, enhanced flooded, or AGM) straight off the label, then check those five things against your owner's manual. Battery Council International (BCI) assigns the group size codes that describe a battery's length, width, height and terminal position, which is why two different brands sold under the same group size will drop into the same tray. If the label is unreadable, the owner's manual or a parts store lookup by year, make, model and engine can usually confirm the same information.

What does the battery group size number mean?

It is a fitment code, not a random model number. Battery Council International standardizes group sizes so a battery's physical dimensions and the position of its terminals are described in a way any retailer can look up and match to your tray and cables. A common code looks like a plain number, such as 35 or 65, or a number followed by a letter, such as 24F or 94R. Get it wrong and the new battery may not fit the tray, may not reach the cables, or may sit against something it should not touch.

How many cold cranking amps do I need?

At least as many as your vehicle maker specifies, and never fewer. Interstate Batteries, a battery manufacturer, describes cold cranking amps as the amperage a battery can supply at 0°F for 30 seconds while it holds at least 7.2 volts — in short, a bigger number is a stronger cold start. Your owner's manual gives the minimum figure for your vehicle; the rating on your current battery is a reasonable starting point too, but only if nobody has already fitted the wrong battery before you. A CCA rating above the minimum will not hurt anything; a rating below it can leave you with a car that will not start on a cold morning.

Can I put a regular battery in a car that came with an AGM battery?

Check the owner's manual before you assume the answer is yes. Interstate Batteries warns that some vehicles will not accept a flooded battery once they are built for AGM, particularly vehicles with an automatic engine start-stop system that cranks the engine far more often than a conventional car does. Installing the wrong chemistry can shorten the life of the new battery, disable the start-stop feature, or trigger a warning message on the dashboard. Do not assume the old battery is correct either — Interstate points out that someone may have installed the wrong type before you owned the vehicle.

What is the difference between AGM, EFB and a flooded battery?

All three are lead-acid batteries; the difference is construction, not the underlying chemistry family. A flooded battery has liquid electrolyte around lead plates — the traditional and least expensive design. An enhanced flooded battery (EFB) is a reinforced version of the same basic design, built to survive more frequent starts. An absorbed glass mat (AGM) battery seals the electrolyte inside a fiberglass mat, which lets it handle the heavier cycling of a start-stop system. The presence or absence of an AGM or EFB marking on the label is usually your first clue to which one you are looking at.

Does the side the terminals are on actually matter?

Yes. The vehicle's positive and negative cables are a fixed length and reach to a fixed spot, so a battery with its posts on the wrong side can leave a cable stretched tight, unable to reach, or forced to cross over the case. Battery Council International's group size system captures terminal position as one of the characteristics that defines a group size, alongside the case dimensions. Reading the terminal layout off your old battery, or off the group size code itself, is the fastest way to avoid buying the mirror image of what you need.

Why does the bracket that holds the battery down matter?

A battery that can shift while you drive is a battery whose case can crack or whose terminals can touch something metal they should not. Hold-down brackets and straps come in more than one shape, so matching the one on your old battery, or asking the parts store to match it, keeps the new battery secured the way the vehicle was designed for.

Sources

Every specification on this page is traced to one of these sources. Tier 1 is a manufacturer document, a published standard, or a government safety authority. See Standards for the full tiering rule.

  1. Tier 1Basic Rules for Battery Care & Maintenance (form 0004)East Penn Manufacturing Co., Inc. (Deka) · accessed 2026-07-29 · re-verification due 2027-01-25
  2. Tier 129 CFR 1926.441 - Batteries and battery chargingOccupational Safety and Health Administration · accessed 2026-07-29 · re-verification due 2027-01-25
  3. Tier 1NIOSH Pocket Guide to Chemical Hazards - Sulfuric AcidNational Institute for Occupational Safety and Health (NIOSH), Centers for Disease Control and Prevention · accessed 2026-08-03 · re-verification due 2027-01-30
  4. Tier 2BCI Group SizesBattery Council International (BCI) · accessed 2026-08-03 · re-verification due 2027-01-30
  5. Tier 1What's an AGM Battery?Interstate Batteries · accessed 2026-08-03 · re-verification due 2027-01-30
  6. Tier 1Understanding CCA in Car BatteriesInterstate Batteries · accessed 2026-08-03 · re-verification due 2027-01-30

Revision history

Current version 1 · updated 2026-08-03 · next review due 2027-08-03

  1. v1 · 2026-08-03First draft. Group size, terminal position, hold-down shape, minimum cold cranking amps and required chemistry all publish as vehicle-specific instructions to consult the owner's manual or the original battery, never as a guessed number — none of these five things is the same across vehicles. Battery Council International (BCI, a trade association, tier 2) is newly proposed and cited for what a group size code standardizes; Interstate Batteries (a battery manufacturer, tier 1) is newly proposed and cited for the cold cranking amps test definition and for its own warning that a start-stop vehicle can refuse a flooded battery. Both are in data/sources-additions-choose-a-replacement-vehicle-battery.json pending admission by scripts/sources_admit.py. The corrosion and sulfuric acid hazard draws on a newly proposed NIOSH Pocket Guide entry (also pending admission) and on the already-registered East Penn Manufacturing care and maintenance document; the hydrogen gas and short-circuit hazards draw on that same East Penn document and the already-registered 29 CFR 1926.441 (OSHA). No competitor page was opened while drafting.

Corrections to this page are listed in the public corrections log. Reports that are credible and not yet verified are listed in the public errata register, and an open one renders above the step it concerns.

Comments and corrections

Found an error? A correction with a manufacturer source is applied and logged publicly. You can also write to corrections@fixchecklist.com.

Every step above carries its own report control, which tags the report with that step so a correction reaches the right place. For anything about the procedure as a whole — the order of the sections, a step that is missing, something that did not match your equipment — use this: report something about this whole procedure.

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