AlanSubie4Life
Efficiency Obsessed Member
do you trust the dashboard data's accuracy?
Depends on what you are referring to. The rated miles (the miles next to the gauge) click off at 230Wh/rmi (or maybe 234Wh/rmi, but I've only ever measured 230Wh/rmi). That is referenced to the trip meter gauge.
However, for recharging those miles, it takes 245Wh per rmi added back (as indicated on the charging screen). And for you with your alleged 94% efficiency, that means 260Wh/rmi from the wall.
In other words, the trip meter reads (perhaps) 4.7% low (234/245) . However there are a lot of moving pieces here, so it's hard to say what is "low" and what is "high".
There is an additional complication that the 310 rmi on your dashboard at full charge aren't really the same as the EPA 310 miles - because you have a reserve energy of a few kWh below 0%/0rmi. So actually each rated mile on the dashboard is more like 0.96 * EPA rated mile (it's a ratio of something like 76/79 or 76/78). So if you never want to go below 0rmi/0% (a good plan), you really only can go 298 EPA rated miles (0.96EPArmi/rmi * 310rmi) at the EPA efficiency. If you want to drive until the car stops, it is possible you could go another 10 or so EPA miles beyond that. But I wouldn't recommend it and you'll probably get stuck. But that's what they do in the EPA test. But they're on a dyno right next to a wall outlet, so it is cool for them.
Anyway, for your cost purposes, all you can really do is what you are doing and measure from the wall. That is accurate - as long as you measure the actual voltage and current directly after your meter (not at the car - though you might want to do that as well, to separate out the various sources of inefficiency).
Meant to quote this above:
https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=46585&flag=1
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