Life time of integrated lithium battery CR2032-1VC 3V


What is the life time of the integrated lithium battery CR2032-1VC 3V ?

V mém Turrisu 1.1 šlape uz pátý rok…

I have Turris 1.1 and this battery started its fifth year.

Maybe a better question would be what the battery is used for, what would drain it?

Most simular equipement i know of, it is used to keep the clock running in case of a power outage. That doesn’t happen often. So the drain (apart from self deischarge) would be rather minimal.

Anywho, this source ( speaks of a self discharge of 1%/year.

This router is intent to be used embedded in a device in environments where it is powered only few hours per day (less than 12hours), few days per week (less than 5days).

There might be also microcontroller(s) on the system that store configurations during a power cycle, least the TO features

PCA9538 microcontroller (16-pin CMOS device that provides 8 bits of General Purpose parallel Input/Output (GPIO) expansion with interrupt and reset for I2C-bus/SMBus applications)

Dug a little bit deeper in the schematics of the TO ( The battery is drawn on page 15 (PWR_schematic) where it supplies Vbat. On the very first page you can see that Vbat is only connected to the CPU_schematic (and PWR schematic).

On the CPU_schematic (page 2) it supplies the CPU 88F6820 on pin RTC_AVDD.

According to (

  • page 35 shows its as the “RTC quiet power supply”.
  • page 104/106 shows its voltage requirements
  • page 120 shows the max. power requirements as 1 microAmp

So as suspected it powers a clock in the CPU during powerfail. When this happens the current drawn from the battery is 1 microAmp max.
The CR2032 has a capacity of about 200 mAh (to 2.6 Volts). This would suggest a standby time of 200.000 hours (excl. self discharge and other effects).
This is more than 20 years! I wouldn’t worry to much.

Hope this help.

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