Brief interruptions during charging a Prime

I noticed on my Sense home energy monitor that when I charge the Prime (I use the factory EVSE at 120V), there are regular interruptions in charge. The first three are at 5 minute intervals, then they extend to 15 minute intervals. The dips last for 15 seconds, and ramp down to zero charge for about 4-5 seconds. See attached screen shots from the Sense monitor.

The software also shows the charge taper at the end of the charge cycle, which is expected. The brief interruptions were not expected. There is no problem with the power receptacle on the wall, and power to the house was not interrupted. This behavior is consistent on each charge.

Thoughts on why these interruptions are apparently programmed into the charge cycle?

 

Do you know why the software does this?

 

Thanks. It must be happy with the first several checks, because then the interval extends to 15 minutes. Hasn't caught fire yet, so it must be working as designed.