I built my own KWH meter. I bought a used meter on eBay for $27.50, meter socket can from Home Depot for $25, cord and 6-20 plug and receptacle...total cost $65-70. I plug in my level 2 Duosida EVSE to the meter and the meter to the 220 line I installed in the garage so I can meter exactly how much power the Prime uses. I found a full recharge when only .8 mile of range was left uses 6 KWH's. See attached photo.