Every battery in India comes with a warranty figure, and almost nobody reads what it means until the battery fails. Then the questions start. Is the replacement free? Do I pay something? Why is the dealer saying my case is not covered? This guide explains how battery warranties are normally structured, shows the arithmetic with worked examples, lists the things that commonly void a claim, and tells you which papers to keep so that a claim goes smoothly. The details differ between manufacturers, so always read the card that comes with your battery. What follows is the general pattern.
Reading the warranty line: free and pro-rata
Warranty terms are usually written in months. You will see two numbers, such as "36 months free replacement plus 36 months pro-rata", sometimes shortened to 36F + 36P or 36M + 36M. The two periods follow each other:
- Free replacement period. If the battery fails in this window because of a manufacturing defect, the manufacturer replaces it with a new battery at no charge to you.
- Pro-rata period. After the free period ends, a covered failure no longer gets a free battery. Instead you receive a credit against a new battery, and the credit shrinks as the battery ages. You pay the rest.
So a "36 + 36" battery has a total warranty of 72 months, but only the first 36 are free. A very common misunderstanding is to treat the big total as if the whole period were free. The first number is the one that protects your wallet.
A warranty like this is also not a guarantee of how long the battery will last. It is the manufacturer's promise to deal with defects within a period. A battery can wear out in normal use before the end of the pro-rata period without the manufacturer owing you anything under free replacement.
What it means in rupees: worked examples
The formula for the pro-rata credit varies by manufacturer, and each has its own rule about which price it applies to, so ask for the exact method before you rely on a number. The examples below use a simplified method and invented round figures only to show how the idea works. They are not a quote and not any specific brand's terms.
Example A: failure inside the free period. Suppose a battery with a 36 + 36 warranty fails after 20 months because of a manufacturing defect. It is inside the free period, so the manufacturer replaces it. You pay nothing for the battery, whatever its price.
Example B: failure inside the pro-rata period. Suppose the same battery fails after 54 months, which is 18 months into the 36-month pro-rata period. In a simple version of the calculation, the battery has used half of the pro-rata period, so you might receive a credit of about half the applicable price on a new battery. If that applicable price were ₹10,000, the credit would be roughly ₹5,000 and you would pay the other ₹5,000. In practice, manufacturers may use a different base price, may round differently, and may apply the credit as a discount and not as a cash refund. The later in the pro-rata period the failure happens, the smaller the credit.
The takeaway is that pro-rata is a discount on your next battery, not a refund of the old one. Think of it as a modest consolation for a battery that did not reach the end of its stated life.
When does the clock start?
Normally the warranty runs from the date of sale shown on your invoice. If you cannot show an invoice, many manufacturers count the warranty from the date the battery was manufactured, which they read from the code on the case. Because a battery can sit on a shelf for months, that can quietly cost you part of your cover. Our guide to reading a battery date code explains how to check when yours was made, and it is worth doing at the time of purchase.
When a battery is replaced under warranty, the replacement commonly carries on with the remaining period of the original warranty rather than starting a fresh one, though this depends on the manufacturer. Ask what applies to yours.
What usually voids or limits a warranty
Manufacturers cover defects in materials and workmanship. They do not cover damage that comes from how the battery was used. Typical reasons for a claim to be rejected are:
- Physical damage. A cracked or broken case, bent or broken terminals, a dropped battery, or damage from an accident.
- A swollen or bulged case caused by overheating or overcharging. This points to a charging or heat problem rather than a defect.
- Burnt or melted terminals and cables. These often indicate a loose connection or overload.
- Tampering. Opened or prised-off caps on sealed batteries, drilled cells, damaged or removed serial numbers and warranty stickers.
- Wrong electrolyte or neglect. Adding acid, topping up with tap water, or letting a flooded battery run dry so the plates are exposed. Our guide to inverter battery maintenance explains the correct routine, and keeping a short note of top-up dates is useful evidence.
- The wrong application. Using a starter battery for deep cycling, a home battery on a commercial vehicle, or a battery on an inverter or charger it was not designed for. Commercial use often carries a shorter warranty than the same battery used at home.
- Charging faults. A faulty alternator, a mismatched or cheap charger, or an inverter set to the wrong battery type, which overcharges or chronically undercharges the battery.
- Deep discharge from neglect. A battery left flat for a long period and then claimed as defective.
- Missing or unclear documents. No invoice, no warranty card, or details that do not match the battery's serial number.
The decision is made by testing. A service technician will normally check the battery's voltage and electrolyte condition and run a load test. If it fails the test and shows no sign of misuse, it is accepted as a defect. If it passes the test, or shows signs of damage or abuse, the claim can be refused. A battery that is simply weak because it is old is not a defect, although a battery that tests badly in the first few years usually is worth a claim.
What to keep
- The tax invoice. It should show the date, the battery model and capacity, and ideally the serial number. Keep a photo of it on your phone as well as the paper copy.
- The warranty card, stamped and filled in by the seller, if the brand issues one.
- The serial number and date code sticker on the battery. Do not remove or damage them. A photograph taken on the day of installation is a useful backup.
- The brand's service contact from the card, along with the seller's contact details.
- A simple maintenance note for flooded batteries: dates of water topping and any service visits.
- The exchange details, if you traded in an old battery. Your old battery's warranty does not carry over to the new one; the new battery's warranty starts with the new invoice.
How a claim usually works
- Contact the seller or the brand's service centre listed on your warranty card, with your invoice and the battery details.
- The battery is inspected and tested, either at a service point or by a technician who visits.
- If it is accepted, you receive a replacement battery in the free period, or a credit against a new battery in the pro-rata period.
- If it is refused, ask for the reason in writing or on the test report, so that you understand what was found.
Warranty processes are slower than a normal sale, and some brands have a limited number of test points. Ask the seller how they handle claims before you buy, not after the battery has failed. If you are comparing brands, the warranty period is only one of the factors; our brand comparison looks at the others.
Questions to ask before you buy
- How many months are free replacement, and how many are pro-rata?
- From which date does the warranty start, and what happens if I lose the invoice?
- Who handles a claim, the dealer or the manufacturer, and is there a doorstep service for large batteries?
- How is the pro-rata credit worked out, and on what price?
- Is my use, such as an inverter, a commercial e-rickshaw or a generator, covered under the standard terms?
Warranty periods are listed on each product page, and you can compare them across car batteries, inverter batteries and e-rickshaw batteries. Read the free and pro-rata split, not only the headline total, and keep the invoice somewhere you can find it in three years.
