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Any idea how I can track Electric Vehicle charging/costs off a kWhr device?

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  • Any idea how I can track Electric Vehicle charging/costs off a kWhr device?

    I have an OpenEVSE electric vehicle charger (and yes, for the purists I understand it’s not really a charger) that communicates status and data via mqtt. I’ve got an mqtt plugin and am bringing these data into homeseer and have a device that reports the total kWhr “dispensed” from the charger.

    This is total isn’t 100% consistent, in that it resets when the firmware is updated, but my goal would be to log the daily kWhr that are “dispensed” by the charger, and then multiplying by $0.07 would give me a rough idea of our EV running costs. As a bonus it might be cool to compare to similar gasoline prices, since I have an average mi/kWhr from the cars that would ballpark it.

    I have have no idea how I’d do this in HS. The energy module seems to have the bones, but my research indicates this is an abandoned feature. My other thought is having a bunch of devices that total each days use, week use, and month use but that seems excessive. Any thoughts on how to get started? I’m moderately technically competent and can muscle my way through JavaScript and similar but haven’t yet tried scripting in HS.

    Im on HS in Linux if that matters.

    Thanks for for any thoughts/guidance!

  • #2
    I would use a power monitoring device like the Aeotec Labs ZW095 ZW095-A Home Energy Meter or equivalent installed in your panel ( I take it you're using 240 volt split phase charger on a dedicated circuit) to monitor the daily power in kwh consumed by your charger, create a virtual device to hold a value or kwh (combining both legs of the power used) and/or cost of the daily charge. You can factor in the cost/kwh + any taxes on your electricity. Each night, have it update the virtual device via a nightly script. If you want to get even more fancy, you can use Jon00's charting utility to store/chart this data for graphical representation.
    I do the first part for my pool. I do chart the whole house consumption and do hold the previous day of whole house consumption in a virtual device. While I don't have a device to hold the data for the pool, I do write the log each night at midnight, zero/reset the device values. This gives me a fairly accurate account of the energy used each day.

    Robert
    HS3PRO 3.0.0.500 as a Fire Daemon service, Windows 2016 Server Std Intel Core i5 PC HTPC Slim SFF 4GB, 120GB SSD drive, WLG800, RFXCom, TI103,NetCam, UltraNetcam3, BLBackup, CurrentCost 3P Rain8Net, MCsSprinker, HSTouch, Ademco Security plugin/AD2USB, JowiHue, various Oregon Scientific temp/humidity sensors, Z-Net, Zsmoke, Aeron Labs micro switches, Amazon Echo Dots, WS+, WD+ ... on and on.

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    • #3
      How do you total the devices? I already have my kWhr in homeseer so don’t need a hardware monitor (the OpenEVSE hardware does this for me), and I’ve got a device called “OpenEVSE wHr.”

      Would I essentially:
      1) Create a new virtual device called “Energy Dispensed” or similar
      2) Run an event at midnight that determines the differential and multiples by my energy costs?

      #2 is where I’m struggling a bit as it feels like I’d need a ton of devices. At a minimum i think I’d need “Total kWhr yesterday” so I could get the difference with today to get my usage, “Total kWhr dispensed.” If I wanted a rolling monthly total I’d need another dozen devices.

      I'm not against a whole bunch of devices, it just seems rather inelegant so I’m wondering if there’s a better way.

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      • #4
        Sorry, perhaps I misunderstood - if your OpenEVSE is already providing this as a total, there is no need to total any devices. My comment was based on monitoring each leg of power your hardware was consuming.
        If the OpenEVSE only continuously increments the power usage, #2 would be the way to go. You'll need to compare to the previous day. Each day just before midnight (11:59:59), record the power in a VD. Then take the previous day VD device minus current day and record that in a separate device - done in a script at 11:58:59. The first day's data will be bunk, but thereafter should be fine. My guess is you only need 3 virtual devices (one you can hide - previous day,difference or daily in another and one for costs) - this would be just for kwh. You could create another to hold the calculated cost. Using Jon00's charting read each day into the database. Again, with the charting app, you can create charts based on any calendar period - get min, max, average usage. It's really a great package.
        HS3PRO 3.0.0.500 as a Fire Daemon service, Windows 2016 Server Std Intel Core i5 PC HTPC Slim SFF 4GB, 120GB SSD drive, WLG800, RFXCom, TI103,NetCam, UltraNetcam3, BLBackup, CurrentCost 3P Rain8Net, MCsSprinker, HSTouch, Ademco Security plugin/AD2USB, JowiHue, various Oregon Scientific temp/humidity sensors, Z-Net, Zsmoke, Aeron Labs micro switches, Amazon Echo Dots, WS+, WD+ ... on and on.

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        • #5
          This appears to be one of those times I overcomplicated in my head. Using EasyTrigger I setup daily, weekly, and monthly accumulators. Next up is to install the charting plugin, but I broke my finger today mountain biking so typing is slow so that will wait... Thanks for the guidance!

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