My 4 year old Dell Inspiron 15R's CMOS battery is running out (has run out ?). I know this because when I turn the laptop on it keeps on giving me 5 beeps till Windows loads.

I am sure replacing the battery is going to be the recommended practice, but I cannot get to it in the immediate future. What are the implications if I do not replace the battery ? I have never changed any BIOS settings so I have been using the defaults anyway.

I did read this What are the negative effects of a flat CMOS battery? question but wanted to be know if the same is applicable to laptops ?

  • I don’t know if it is a laptop specific thing or a vendor/make/model specific thing. Oct 9, 2015 at 23:54
  • Date and time will be reset to factory default if cmos goes dead unless you keep it plugged in.
    – Moab
    Oct 9, 2015 at 23:58
  • Is that all????
    – Xavierjazz
    Oct 10, 2015 at 0:32

1 Answer 1


Date and time are going to be reset every time power is removed from the machine. Your BIOS settings will remain intact however, unless Dell decided to implement it as such where it emulates the behavior of older machines where settings also clear upon battery backup removal.

Modern machines store BIOS data in a non-volatile flash memory, usually a SPI Flash or similar. Older machines actually required the CMOS battery to provide power for a small static RAM that held the settings -- the data is physically lost if power is removed.

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