I now have a Wireshark trace that shows my Wemo plug returning a single bad power sample to Sense. I see both Sense reporting, and the Wireshark trace showing the Wemo reporting, a relative constant 40W power consumption. Then for one 2s sample, Sense reports 5177W (but with a zero-wide spike up about 2x as high, so in the 10kW range), and I see from the Wireshark capture of the Wemo plug that it reports 10314W for one sample. (I enabled Wireshark TCP checksum validation, and it says the checksum is goo.)
Clearly my Wemo plug is sending out bad power data, erroneously high, several times a day on average. Do others see this behavior too with their Wemo smart plugs when viewed via Sense? Perhaps Wemo could fix the problem on their end with a firmware update…I’ll actually see if they have a support team like Sense does. That said, if this is a wide spread issue, then I could see Sense implementing some kind of work around to ignore samples that clearly erroneously high. I really want to avoid smart plug device power meter graphs like the following, which are useless with a huge erroneous spike in the middle of the data causing the Y-axis to be scaled all wrong:
Anyway, I’ll be swapping out this Wemo for a HS110 soon, since I want this switch to turn back on following a power loss.