So the conclusion must be:

If you want the best accuracy, you should NEVER read out the the RTC !

Please can you tell me, which RTC you mean, that I avoid to use it.
I hope there are still other manufacturers, which made RTC usable as RTC also.

I expect from every device, which was named RTC, that the reading and counting must be fully independend in any case !


I test now the DS1994 and detect a deviation of about 1 second per day.
I read it out with the maximum rate.
The deviation seems to be the same if the power was switched off.

But now I will test it more precise.


Peter