Using a plug-in wattage meter to track charging?

Discussion in 'Prime Plug-in Charging' started by Toyo_Tom, Nov 8, 2019.

  1. Toyo_Tom

    Toyo_Tom New Member

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    I am a new owner of a 2020 Prius Prime and wanted to see how much my charging was adding to the electric bill each month. I had a plug-in meter made by Intertek (ASIN B07M8JKLG5 on Amazon) so I decided to try using it. However, when I did this, I discovered the next morning that the charging did not complete. I am guessing that this meter can't pass enough current through to let the charging work, although it is rated for 15 amps so I don't see what the problem is.

    So now I am seeking either a way to make this meter work or to find one that will do the job. I am not one to go tinkering around so it needs to be just a simple plug-in pass-through meter, although I do admit that some of the DIY projects that I have seen posted here are quite impressive. Unfortunately, that sort of thing isn't for me. I am hoping to monitor continuously for at least a month, so that is also a consideration (I have read that some plug-in meters aren't really made for long-term monitoring). Remote monitoring via Android app would be great but isn't absolutely necessary.

    Thanks in advance for any assistance.
     
  2. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Try something from The Energy Detective’s line. You can get sensors for different arrangements and they’re great for long term recording and stats reporting.

    Not cheap, but the good tools never are.
     
  3. jerrymildred

    jerrymildred Senior Member

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    Kill-a-watt is what I was using when charging at 120V. Inexpensive and never any problems except that it would forget everything if there was a power outage. And I don't know how accurate it was.
     
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  4. Colorado_Hiker

    Colorado_Hiker Junior Member

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    Hi...
    I think a "split-core" meter will work better for you, but it does require some electrical wiring and installation. I purchased a "bayite AC 80-260V 100A BYT-VAEM-034 Digital Current Voltage Power Energy Analyzer Meter Ammeter Voltmeter with Open-Close Current Transformer Split Core CT" from Amazon.
    By being a split-core, there is no pass-through, but very simply, there is a metal ring that is placed around one of the "hot" power wires that goes to chargers electrical socket.
    Here's a few pictures of the final product. From the first picture which shows the meter and the outlet, there are two thin wires that connect from the meter to the metal ring (the split-core). They are routed through the vertical piece of electrical conduit and the ring is placed around one of the "hot" wires in the socket. There's also another wire that goes from the socket to the meter (through the vertical electrical conduit) that provides power to the meter. The other picture shows a close-up of the meter.
    Yes, it does require some skill and ability to do the installation. But it works well! If this is too daunting, then a "kill-a-watt" meter would probably work if you're only doing 120v charging..
    1.jpg
    2.jpg
     
    #4 Colorado_Hiker, Nov 8, 2019
    Last edited: Nov 8, 2019
  5. Salamander_King

    Salamander_King Senior Member

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    I am with @jerrymildred. P3's Kill-a-watt works fine for 120V OEM EVSE. Power Monitor - Kill A Watt EZ | P3 As you may know there are many copies of Kill-a-watt meter exist. Some are out right counterfeit, others are just look alike or not so look alike. Many of them do not really take the rated max sustained amp as you found out. Authentic Kill-a-watt EZ meter, I purchased at Home Depot, works fine. I have been using it over two years now almost every night, continuously plugged into the wall without any problem. EZ model P4460 is a bit more expensive but it has internal memory function that allows to retain the data when unplugged or power is interrupted, so it is more convenient than the cheaper original Kill-a-watt meter P4400 Kill A Watt Meter - Electricity Usage Monitor | P3.

    IMG_20190313_055527.jpg
     
    #5 Salamander_King, Nov 8, 2019
    Last edited: Nov 8, 2019
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  6. jerrymildred

    jerrymildred Senior Member

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    That's exactly what I use for my L2 EVSE. Really nice! And I think it's the best solution, but it sounds like @Toyo_Tom doesn't want anything that involved for installation. I put mine on top of the breaker sub panel I had to install since the old one was full. It's right next to my driver's door and above the work bench, so it's a perfect place for recording the readings before I get in the car.
    IMG_6964 copy.jpg

    I thought they had one with memory but was too lazy to look for it. ;)
     
  7. Salamander_King

    Salamander_King Senior Member

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    Here is the Q&A from Amazon site. P4400 is the original Kill-a-Watt meter sold at ~$20. P4460 with memory function is the Kill-a-Watt EZ meter I use sold at ~$25.

    what is the difference between the p4400 and the p4460?

    https://www.amazon.com › ask › questions

    This device, the P4400, will reset all of its timed measurement values to zero if power is lost or the device is unplugged. The P4460 has "non volatile" memory, using a battery to provide the necessary voltage to power the (S)RAM memory, which means that it will not lose the data if power to the 4460 is lost.
     
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  8. MTN

    MTN Member

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    Pretty easy to just estimate based on how many times you will do a full recharge per month. Round up to 6.5 kwh for a full charge, estimate how many days/month you'll do that, and multiply by your $/kwh. A full charge costs us $1.235 @ .19/kwh.
    Gas is currently $4/gal. At around $2.80/gal is the breakeven point.
    Or you could also look at your monthly electric bill after owning the Prime for a couple of months and compare to last years month.
     
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  9. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Neat! I have a pair of those to steer my loads when I have to run the house on the backup generator. I had to make my own backing plate for a duplex mount, though.
     
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