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Just wondering usually how long does CMOS battery last on a regular motherboard?
I read that motherboard leakage current of about 3 - 6 micro ampere. I did a calculation below but I believe that i may have missed something. What is the minimal voltage required for a motherboard's date/time function to work correctly?
Life of battery (down to 0V):
Normal Case (leakage current = 4 µA).
Battery capacity = 225 mAH / 4 µA
= (225 x 10^(-3)) / (4 x 10^(-6)) hr = 56250 hrsOne year has 24 x 365 hrs = 8760 hrs
Total battery life (from 3V -> 0V)
= 56250 hrs / 8760 hr per year = 6.42 years
@OP: To be considered also is the low voltage threshold defined by the Motherboard manufacturer. Its not necessary that the battery be completely dead (i.e at 0V) before it starts acting dead. – Bhargav Bhat – 2012-03-02T03:44:15.937
@Moab: The battery doesn't seem to be a rechargeable type, wikipedia lists it as a common button cell that is used in calculators and watches etc.
– Bhargav Bhat – 2012-03-02T03:46:27.087@Moab: Li-ion technology allows for rechargeable batteries, but the
CR2032
is not a rechargeable battery. – Bhargav Bhat – 2012-03-02T04:15:07.097@Moab: I should have been more clear in my previous post. The
– Bhargav Bhat – 2012-03-02T05:22:23.703CR2032
is not a lithium-ion battery. It's simply called a lithium battery because it uses lithium metal or lithium compounds in the anode. See this wikipedia page for details.