Due to the limited characters on the screen of the Acaia Pearl, it can only display the time as 0:00 and the three remaining characters are used for the weight with an accuracy of 1 gram. This also means that the timer will top out at 9:59 and the weight display will show up to 999g. If you are using any firmware before v2.0, when the timer gets to 9:59, it will continue to display that, but it is actually still counting up. This means the scale will not automatically sleep and the battery will drain if left on. This is corrected in v2.0.
If you would like to update your firmware, you can find a guide here.