Support official RTC battery for Pi 5

[abuelomg]

Hi all

Now that the PI5 has a built-in RTC and an official rechargeable battery is available, we can ensure that this battery gets charged by applying

Code:

dtparam=rtc_bbat_vchg=3000000

in /boot/firmware/config.txt ...but, of course, only if the "official rechargeable" battery is used.

A checkbox for adding this parameter would be helpful, as one should not modify the /boot/firmware/config.txt directly.

Best regards
Marcel

[Tim Curtis]

What the battery used for?
Documentation on the param rtc_bbat_vchg?

[abuelomg]

The battery ensures that the system time is kept across powerdowns even if NTP is unavailable. It also supports timers and a wakeup function for scheduled poweron.

See https://github.com/raspberrypi/documenta...i/rtc.adoc

Some people attach a non-rechargeable cell, this might be the reason why charging is not enabled by default. But the "official" cell is a rechargeable one. I order the battery with every pi5 and attach it on top of the ethernet connector.

[Tim Curtis]

Thanks for the link to the documentation.

The "accurate clock" aspect of this feature is less interesting than the alarm/wakeup capability but I don't see that as part of your usage scenario which is more about an option to add the "charge battery" line to config.txt

But if more people want something like this or a dev wants to contribute the feature via a PR I'll add to the TODO list.