In short: the CMOS battery (also called the BIOS or RTC battery) is a small cell that keeps the BIOS settings and the clock alive while the laptop is disconnected from power.
ThinkPads do not use one universal CMOS battery - the series and model year are decisive.
Classic ThinkPads from roughly 2008-2018 (T, X, L, E, W, P) share the same 2-pin cell, but newer models (2019+, T490/T14) and the X1 Carbon / X1 Yoga line use different batteries.
Below you'll pick the right one for your model. We match the type, size and connector of the backup (CMOS/BIOS) battery according to the official Lenovo Hardware Maintenance Manual, listing proven replacements.
Which CMOS / BIOS battery fits which ThinkPad?
Classic ThinkPad T / X / L / E / W / P (model years ~2008-2018)
A single 2-pin CMOS battery, in practice interchangeable between FRU numbers 02K6572, 02K7078 and 01HY789. It fits the whole generation: T series (T400-T480 and the "s" versions), X (X200-X280), L (L4xx/L5xx), E (E4xx/E5xx), W (W5xx), P (P50-P72) and ThinkPad Yoga of those years.
- CMOS BIOS battery ThinkPad T/X/L/E/W/P - FRU 02K6572 (full list of compatible models on the product page)
- CMOS BIOS battery ThinkPad - FRU 02K7078 (equivalent of 02K6572)
- CMOS BIOS battery ThinkPad - FRU 01HY789 (equivalent, incl. P50-P72 series)
Newer ThinkPads - model years 2019+ (T490, T14, T14s, P14s, P16s, L13/L14/L15, E14)
This generation uses a different battery than the classic one - do not fit the 02K6572 cell.
- CMOS BIOS battery Lenovo T490s T14s P14s L13 L14 L15 - FRU 01AY996
- CMOS BIOS battery Lenovo T490s T14 P14s P16s E14 - FRU 01AY997
ThinkPad X1 Carbon
- X1 Carbon gen 2 / 3 / 4 (2014-2015) and X1 Yoga - FRU 00HN933
- X1 Carbon gen 5 / 6 / 7 / 8 / 9 / 10 - FRU 01HY008
- X1 Carbon gen 12 / 13 and X1 2-in-1 Gen 9 - FRU 5B10W13979
ThinkPad X1 Yoga
Older ThinkPads (e.g. X60 / T60)
What is the CMOS battery for and how do I know it's dead?
The CMOS battery powers a small memory that holds the date, time and BIOS settings while the laptop is off and unplugged. When it runs out, those settings are lost after every disconnection from power.
Frequently asked questions about the CMOS / BIOS battery
Which CMOS battery fits my ThinkPad?
The series and model year decide. Classic ThinkPads T, X, L, E, W and P from roughly 2008-2018 use the same 2-pin cell (FRU 02K6572 / 02K7078 / 01HY789).
Newer 2019+ models (T490, T14, P14s, L13/L14/L15, E14) use a different battery (01AY996 / 01AY997), and the X1 Carbon and X1 Yoga line have their own separate batteries. If in doubt, give us your serial number.
How do I know the BIOS battery is flat?
The most common symptoms are the date and time resetting after every shutdown, lost BIOS settings, real-time clock (RTC) error messages at boot and sometimes a longer start-up. These are typical signs of a depleted CMOS cell.
How is the CMOS battery different from the main laptop battery?
The main battery powers the whole laptop while running on battery, whereas the CMOS battery is a separate small cell that only keeps the BIOS settings and clock alive while the laptop is off. They are two different parts with completely different roles.
Does a CMOS battery from a ThinkPad T430 fit a T470s?
Yes. The whole classic ThinkPad generation from T400 to T480 (and the X200-X280, L, E, W, P50-P72 series) uses the same 2-pin CMOS battery, so a cell described "for T430" also fits a T470s and the other models from that period.
Which CMOS battery should I use in a newer ThinkPad (T490, T14, 2019 models)?
For these models do not use the classic 02K6572 cell. Model years 2019 and later (T490, T490s, T14, T14s, P14s, L13/L14/L15, E14) require a battery with FRU 01AY996 or 01AY997 - a different part from the older generation.
Does a regular ThinkPad CMOS battery fit a ThinkPad X1 Carbon?
No. The X1 Carbon line has its own CMOS batteries depending on the generation: gen 2-4 is FRU 00HN933, gen 5-10 is 01HY008, and gen 12-13 is 5B10W13979. The X1 Yoga also has a separate battery (5B11J02395). Do not use the classic T/X/L/E cell here.
All batteries are original or compatible parts identified by FRU number. Shop: abcdeal.eu · Allegro: allegro.pl/uzytkownik/abcdeal.