Way to log a device's wattage over time?


Hi all, is there a way to log/graph a device’s wattage throughout its run period? I have a device that turns on randomly (actually via a float switch, but “random” in this context) and runs for a short period (5-30 minutes). I would like a way to record/graph the wattage over this period. Today the only way I can do this is sti in front ofthe app and wait for the device (or set up a ‘device on’ alert and then watch).

In case anyone is wondering: yes, still my septic pump. It starts at around 900 watts, and then if/when the distribution laterals fill up and generate resistance to the pump, the wattage decreases due to hydraulic ‘head pressure’. I recently did some service on the system which reduce the pump-out time a whole lot- and now I want to see if the pump runs ‘all out’ during its 5-6 minute run period or if it still runs into head pressure after the first minute or two (unfortunately my baseline is all anecdotal).

If Sense can’t do this, is anyone aware of a not-too-expensive data logging device that I can install inline on the pump’s feed line?



Can’t tell from your message if Sense is reliably detecting on and off events for your septic pump, but your reference to alerts indicates yes. If “yes” - Use IFFFT for logging
“no” - Use a power logging smartplug like an Eve Energy. I wish the HS110 TP-Link smartplug actually logged history, but the Kasa app only provide power usage aggregates.


Thanks for the reply Kevin! ! I am using IFTTT for logging the on/off cycles, but what I want now is the instantaneous wattage during the intervals where the pump is running. I’m not sure that the Eve device will do logging? At least not the things I’ve been able to find.

BUT- in my quest for that eve device- I’ve found this DIY “Tweet-a-watt” that may be very helpful for not only this situation (although I’d have to temporarily un-hardwire it and make it cord-and-plug) but also for general usage for identifying devices that sense has found. So, for instance, you’d put it on a refrigerator, and see if the twee-a-watt’s cycles matched up with an unknown device that Sense has found. Think I’ll pass this on to our facebook community to see if anyone has done something like this yet…


I have a couple of Eve Energys. I bought them specifically for doing energy logging - and they don’t require continuous WiFi to so it. Two caveats about Eve Energy though:

  • It doesn’t have a web app. Connects to phone app and Apple HomeKit by Bluetooth Smart, which has a range of maybe 30 meters with walls etc. Downloads the log to via the Eve phone app, and can export log to text.
  • Doesn’t log instantaneous power (even Sense doesn’t do that - not sure if power meter gives 1/2 second average power, or 1/2 second single datapoint samples of the actual power). Eve app gives power average for every 5 minute increment.