RTC battery life

Question

Hi all,

we have 5 LattePanda Sigmas running sporadically (maybe 1-2 times a week for a few hours).

We use the auto power on setting.

On all 5 we already had to exchange the RTC battery. On one system twice already.

Is this a normal behaviour? Bad batch of RTC batteries?

I appreciate your feedback. :)

Jason.Miao · Answer

The CR1220 is tiny — only 40 mAh — and the standard BIOS auto power-on keeps the RTC circuit alive between boots, so it drains in months instead of years. DFRobot has an Auto Power-On BIOS that triggers on AC plug-in instead of the RTC, which stops the drain entirely. Flash that firmware and the batteries should last normally. If they still die fast after the switch, the RTC charging circuit on that board is probably leaky.