Most batteries show their age on a sticker or a code. Common formats are a month and year like "11/26", or a letter for the month (A is January, B is February, and so on, often skipping I) and a number for the year. Warranties usually have a free-replacement period, and some add a prorated period after it. Keep your receipt. It's the easiest proof of when your warranty started.
Where to look
- A sticker on top or side with a month and year, or a punched-out date.
- A code stamped into the case near a terminal or on the side.
- A code on the label, often with other letters and numbers.
On batteries hidden in trunks, under seats or behind covers, you may need to remove trim to see it.
Common formats
Every maker does it differently, and some change over time. Common patterns:
- Month/year sticker: "11/26" means November 2026.
- Letter plus number: a letter for the month and a digit for the year. "K6" might mean November 2026 in a scheme where A is January and I is skipped. Different brands use different starting points.
- Longer codes: sometimes the date is buried in a string, like the fourth and fifth characters.
If you can't decode it, a photo of the label helps. Or tell us the brand and we'll look.
Made date vs. installed date
The code shows when the battery was made. It may have sat in a warehouse or on a shelf for a few months before it went into your car. For warranty, the purchase date usually matters, which is why the receipt is important.
How warranties work
Free replacement period
If the battery fails within this period, usually measured in months from purchase, you get a replacement at no cost. Terms vary by brand and battery line.
Prorated period
Some batteries add a period after free replacement where you get partial credit toward a new battery, based on how much time is left. Prorated coverage has become less common.
What the warranty number means
A longer warranty usually means a better-built battery. But it's not a prediction of how long yours will last. It's the maker's bet on when failure rates start to climb. In Florida heat, batteries tend to fail closer to the end of that range. How long batteries last in Florida.
What usually voids a warranty
- Wrong battery for the car. A standard flooded battery in a start-stop car, for example.
- Physical damage. Cracks, melted posts or damage from installation.
- Charging system problems. A battery killed by a bad alternator or overcharging may not be covered.
- Commercial use on a battery sold for personal use.
- No proof of purchase.
Read the terms for your battery.
A warranty claim usually means a test
Most warranty claims need the battery tested. A battery that's just discharged, because the lights were left on, isn't defective. It needs a charge.
Our batteries
When we install a battery, you get a receipt with the battery, the date and the warranty terms. Keep it in the glove box or take a photo. If you think a battery we installed has failed, call us, and we'll test it.
Buying a new battery
When you buy a battery anywhere, look at the date. A battery that's been on the shelf a long time has been slowly self-discharging. Fresher is better. Finding your battery size.
A new battery that died
If a battery fails quickly, the cause is often something other than the battery. Why a new battery died.
Florida and warranties
Because heat wears batteries down faster here, more batteries in Florida fail within or just after their warranty than in cooler states. That's not a sign of a bad battery. It's the climate. It's one more reason to keep the receipt, and to get the battery tested if it starts acting weak near the end of the free-replacement window.
Other things people ask about this
How do I tell how old my car battery is?
Look for a date sticker or code on the case or label. Common formats are month/year or a letter for the month and a number for the year.
Does the warranty start when the battery was made or bought?
Usually when it was bought, which is why the receipt matters.
Will my warranty cover a battery that died because I left the lights on?
Usually not. A drained battery isn’t defective. It needs a charge and a test.