Buying a replacement laptop battery is like finding a key for an old lock. The part numbers are the key code, and they matter more than the laptop's name. Voltage, connector and dimensions are the cut of the key: if any of them is off, it will not turn. Capacity is how long the key keeps working per charge. Firmware and authentication are the lock's security pins, which can reject a copy. Match the code and cut first, then compare capacity and quality.
The code printed on the battery label and the laptop maker's own spare part number.
When it matters: The most reliable way to match a replacement. Read the label on your old battery rather than trusting the laptop's model name, which can cover several battery types.
The laptop models this battery is listed to fit.
When it matters: Trap: one laptop name can use different batteries by year, screen or CPU option. Confirm the battery code as well as the laptop model.
Other part numbers this battery can replace, including older or regional codes for the same pack.
When it matters: Helps when your old label shows a different code than the listing. Cross-check against the maker's parts list where possible.
Whether the battery is made by the laptop maker (OEM), an equivalent built to the same design, or a third-party replacement.
When it matters: OEM packs cost more but match the original's cells and firmware. Third-party packs vary widely in cell quality and real capacity.
Whether the battery label shows when it was made.
When it matters: Lithium cells lose capacity even on the shelf. A recent date means more usable life. Old stock sold as new is a common problem.
The battery's rated voltage, such as 11.4 V or 15.4 V.
When it matters: Must match the original. A different voltage means a different cell layout and will not work, even if the connector fits.
How many lithium cells are inside and how they are wired, written like 3S1P (three in series, one in parallel).
When it matters: The series count sets the voltage and must match the original. Parallel groups add capacity.
Stored energy in Wh (watt-hours). The most reliable way to compare batteries.
When it matters: Compare Wh against the original battery. A much higher claim than the original in the same size is a warning sign of an inflated rating.
Capacity in mAh (milliamp-hours) at the battery's voltage.
When it matters: Only compare mAh between batteries of the same voltage. Wh is safer for comparisons.
Skip it if you compare by Wh.
Where the capacity figure comes from: the maker's printed label or a seller's claim.
When it matters: Seller claims on cheap packs are often higher than real capacity. Label figures from the original maker are more trustworthy.
The plug that joins the battery to the motherboard, and how many pins it has.
When it matters: Must match exactly. A connector that looks similar with a different pin count or layout will not fit, and forcing it can damage the board.
How long the battery's cable is and where it leaves the pack.
When it matters: A cable that is too short or exits on the wrong side will not reach the motherboard socket.
Skip it if: Skip it for batteries that plug in directly without a cable.
The battery's physical size, in millimeters.
When it matters: Must fit the bay. A thicker pack can press on the touchpad or stop the bottom cover from closing.
How the battery is held in place: screws, clips or adhesive strips.
When it matters: Glued batteries are harder to remove and need care to avoid puncturing cells. Screwed batteries are the easiest to swap.
Whether a larger battery takes the space of another part, such as a 2.5 inch drive bay.
When it matters: Some laptops offer a bigger battery only on versions without a 2.5 inch drive. Installing it means giving up that drive.
Skip it if: Skip it when it says none.
A security chip the laptop uses to check that the battery is genuine.
When it matters: Some laptops refuse to charge, or show warnings, with non-genuine packs. Check reports for your model before buying third-party.
SBS (Smart Battery System) is the standard a battery uses to report charge level, health and temperature to the laptop.
When it matters: Without accurate reporting, the charge gauge can jump or the laptop can shut down early.
Whether the battery is expected to work fully with the laptop, with pairing warnings, or is unknown.
When it matters: A pack that fails pairing may charge slowly, report wrong levels or show constant warnings. Prefer packs listed as full function.
Circuitry inside the pack that stops overcharge, overdischarge, short circuits and overheating.
When it matters: Essential for lithium batteries. Cheap packs with weak protection are a fire risk.
Safety and transport tests the battery has passed, such as UN38.3 for shipping lithium batteries.
When it matters: A pack with no stated certifications is a warning sign. Certified packs have passed basic safety testing.
The UN code used for shipping lithium batteries, which sets how they can travel.
When it matters: Affects shipping speed and method, not performance. Air shipping of lithium batteries has stricter rules.
Skip it if: Skip it as a buyer; it only affects delivery.