How can a CMOS battery store data?

How does a CMOS battery store information on it? I know it stores information such as the time, date, passwords and drive configuration, but how? How can a battery store data?

The CMOS battery does not store data. The CMOS battery ensures that the CMOS chip, which does store data, has power. CMOS memory requires power to retain data, so the battery is necessary when no external power is supplied to the computer.

This is why a jumper is usually removed from the motherboard to reset the CMOS, as doing so interrupts power to the CMOS chip long enough to clear the data.

A sign of impending CMOS battery failure is when the computer's real-time clock begins to lose track of time when the system is off and not powered by another power source.

On many newer computers, the BIOS configuration data is stored in flash memory, and the battery serves solely to maintain the real-time clock. In such systems, it is called the "RTC battery" (an example is on page 29 of the HP Pavilion dv6z-3000 Select Edition service manual). RTC battery failure in such systems will cause the clock to lose track of time when the system is disconnected from power, but will not result in loss of BIOS settings.

The battery itself does not store the info. The battery is used to keep a small amount of memory (static ram to be exact) running so that the settings are not lost. Additionally, the battery keeps a clock running so that the time and date are correct when the computer is turned on again.

Interesting side note - when running on the battery, the clock in not very accurate and the time can drift.

The CMOS battery does not store data, it's a BATTERY. The battery provides power for the CMOS SRAM chips that actually hold the memory.

Incidentally, there is no such thing as a CMOS battery. The battery that powers the CMOS is just a regular battery that happens to power CMOS chips.

CMOS stands for "Complementary Metal-Oxide Semiconductor" and it refers to the construction of the chips.

The battery itself doesn't store data. The CMOS battery (or BIOS battery) powers a CMOS that stores data for the computer itself which can be viewed on the BIOS. All of this is done through the motherboard.