Wall meter to measure power usage?

[alxwhy]

Sorry if this is a dumb question. I just got my Model 3 and I'm wondering if my electricity loss from charging is normal. I charge daily and my PGE account shows power usage of 34-35kWh during charging and my model 3 shows power usage of 22-24kWh since my last charges, which is an efficiency of 63% to 70%. I sort of understand that there is power loss at different stages of the charging process, but I'm not sure if 30-37% of power being lossed during the charging process is normal or not. I am using the UMC with a nema 14-50 outlet and charging to about 80% (250miles).

please excuse any incorrect lingo I am using.

 

[israndy]

The first thing that comes to mind is, you do know that your account is showing you the electricity usage for the entire house, not just the car. So if you don't charge the car, what's the number of kWh's that go by in that same period of time? For example, I use w/o turning anything on, about 1.1 kW's, so after 8 hours that's 8.8 kWh w/o turning anything like a TV or Hot Tub, or Dishwasher, or Washer/Dryer on. Several people here have gotten meters that attach to the circuit going to the UMC so that they can see only THAT electricity. I cannot wait to hear them chime in with their results.

-Randy

ps. NO lingo issues in your message

 

[alxwhy]

The first thing that comes to mind is, you do know that your account is showing you the electricity usage for the entire house, not just the car. So if you don't charge the car, what's the number of kWh's that go by in that same period of time? For example, I use w/o turning anything on, about 1.1 kW's, so after 8 hours that's 8.8 kWh w/o turning anything like a TV or Hot Tub, or Dishwasher, or Washer/Dryer on. Several people here have gotten meters that attach to the circuit going to the UMC so that they can see only THAT electricity. I cannot wait to hear them chime in with their results.

-Randy

ps. NO lingo issues in your message

i average 0.3 kWh per hour for other things during night time charging, which i did take off from the total electricity usage just for the car charging.

 

[TromboneKenny]

Sorry if this is a dumb question. I just got my Model 3 and I'm wondering if my electricity loss from charging is normal. I charge daily and my PGE account shows power usage of 34-35kWh during charging and my model 3 shows power usage of 22-24kWh since my last charges, which is an efficiency of 63% to 70%. I sort of understand that there is power loss at different stages of the charging process, but I'm not sure if 30-37% of power being lossed during the charging process is normal or not. I am using the UMC with a nema 14-50 outlet and charging to about 80% (250miles).

please excuse any incorrect lingo I am using.

Hi, when you posted this I just had my meter on the 14-50 outlet installed so I wanted to wait a bit to get some data. I know when the car and app says its pulling 8kW the wall meter says ~7955W used. I don't think I've compared aggregate numbers because I've been charging in different places, but I could run it over a week or so and see. (I think the data apps like TeslaFi might give you those numbers easily.) Based on that info, 30-37% power loss seems high.

If PGE shows you an hourly graph of energy, you might be able to better estimate what the car is taking if you set it to delay start at a specific time (like 3am) when you know your house energy use is minimal (no water heater, dishwasher, etc. running). I think it's likely other things are getting lumped into your nightly usage higher than average that's skewing the numbers?

 

[Rlrl79]

I ordered this from eBay AC Digital LED Power Meter Monitor Voltage KWh Time Watt Energy Volt Ammeter | eBay . You need to select the option for the 100amp current transformer, its $17 total. Works well. I got a dual gang box at Lowes and a dual gang blank plate. A little love with a Dremel tool and the meter is neatly mounted in my garage wall.

I ordered this from eBay AC Digital LED Power Meter Monitor Voltage KWh Time Watt Energy Volt Ammeter | eBay . You need to select the option for the 100amp current transformer, its $17 total. Works well. I got a dual gang box at Lowes and a dual gang blank plate. A little love with a Dremel tool and the meter is neatly mounted in my garage wall.

Would I need 2 sensors for each 120v for 2 wire/240 volt connection?

 

[Rlrl79]

I ordered this from eBay AC Digital LED Power Meter Monitor Voltage KWh Time Watt Energy Volt Ammeter | eBay . You need to select the option for the 100amp current transformer, its $17 total. Works well. I got a dual gang box at Lowes and a dual gang blank plate. A little love with a Dremel tool and the meter is neatly mounted in my garage wall.

Did you have to get 2 sensors for each 120v wire?

 

[SDRick]

One sensor is all you need as the meter will detect 240V when the two power leads are connected..

 

[brkaus]

Did you have to get 2 sensors for each 120v wire?

It depends. If it is a 240v device that is balanced (like an EV), you only need a sensor on one wire.

A small number of 240 devices have some 120v use as well. For example some dryers will have a 120v motor to spin the drum. In this case there is some current returned through the neutral so you wouldn’t get a fully accurate picture with a single current sensor.

 

[SDRick]

For my backup generator I used 2 meters and two sensors, one for each 120V leg. Since we are talking about charging the car I do not believe there is a neutral wire with the Tesla wall charger, hence no imbalance between the two legs.

 

[ai4px]

Sorry guys, I haven't checked in here in a few days. 100A AC LCD Digital Panel Power Watt Meter Monitor Voltage KWh Voltmeter Ammeter 871869001633 | eBay

For the HPWC you only need one current sensor because it is 240v only.