Teensy 4.1 RTC battery life question

M

mcharlesmorrison

Member
Hey all,

I've been using these coin cell batteries one some simple data loggers I made with the Teensy 4.1. I've had these built up and connected for about a year. All of them seems to be basically dead now (when I check voltage it's > .1V). I thought they would last much longer than this.

Just wanted to check and see if maybe the coin cells I bought (linked above) are sketchy, or if there is something else potentially causing this issue? Here's a photo of my setup:

Photo on 10-9-24 at 3.31 PM.jpg


Any feedback would be welcomed! Just thought they would last >> 1 year.
 
They may well be fine - the current draw of the T4.1 RTC is I believe fairly high compared to some. 240mAh spread over 1 year is only 27µA. I know some RTC chips on their own draw about 7µA, which would work well with only 240mAh cell, but the microcontroller on the T4.1 is a very different beast - the process will be completely different for instance, so 7µA may not be attainable - anyway see this thread: https://forum.pjrc.com/index.php?threads/beware-t4x-rtc-power-consumption.64216/page-2#post-349500
 
If you only need to preserve the date/time it might be better to use an external RTC, they'll last a lot longer.
 
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