Choosing a power meter

I only have a 120v receptacle available in my garage, so I charge my 2023 Prius Prime XSE at 120v 12A and keep track of each day's driving performance and charge consumption.

I originally was using this $15 Mecheer PM01-US meter which I estimate reads 2% high:
Note 10.99 kWh reading from the last charge

Yesterday I also used a $12 SwitchBot Plug Mini A2:

which is 2.4GHz WiFi enabled which gave this display of 10.53 kWh in the SwitchBot app:


I stacked them with the Meecher attached to the wall, and the Toyota CCID plugged into the SwitchBot.
The SwitchBot draws 0.8W, so the Meecher 10.99 kWh includes 0.01 kWh (13 hours * 0.8W / 1000 w/kW) drawn by the SwitchBot Plug Mini giving a Mecheer reading of 10.98 kWh drawn by the CCID for last night's charge. Previously I have tested the Mecheer meter to read 2% high but I have been using the readings without adjustment.

The SwitchBot read 10.53 kWh this morning which is 4% lower than the Mecheer reading, so perhaps 2% lower than the actual but I'm going to just use the readings without adjustment.

The SwitchBot meter is much more convenient to read and is the meter I am going to be using going forward.

Yesterday's drive was 33.7 miles at a reported consumption of 4.7 mi/kWh using 80% of the EV mode battery capacity.



I am using 10.6 kWh as the 100% EV mode capacity, and the car estimated the remaining charge as 20%:
- Battery used: 80% of 10.6kWh = 8.48 kWh

- Charging Loss Factor: 10.53 kWh wall / 8.48 kWh battery = 1.24x

Charging with Level 1 CCID lost 24% to voltage conversion, heat, and battery cooling.

(Charging with Level 2 loss is usually around 5%, so I could potentially save 30 cents per charge, maybe $90/year, but having a 240v receptacle installed would cost several hundred dollars right now.)