Four losses, stacked
The defaults describe an ordinary month: 1,000 miles, 30 days, a dash reading 3.2 miles per kWh, twelve charging sessions. The dash accounts for 312.5 kWh. The meter sees 393.7.
The 81 kWh in between arrives in four pieces and they are not the same size. Standing drain at 0.4 kWh a day adds 12 kWh — small here, enormous on a car that sits. Storage loss at 96 percent adds 13.5. The charging loss at 88 percent is the big one at 46 kWh, because it applies to everything that goes in. Preconditioning at 0.8 kWh across twelve sessions adds 9.6 and never becomes charge at all.
The number that matters is per hundred miles
At 16 cents a kWh the month costs $62.99, which is 6.3 cents a mile. Reported to the nearest cent that is 6 cents, and the difference between 6.3 and 6.0 across 12,000 miles a year is $36 — so this page reports the figure per hundred miles instead, where it reads $6.30 and nothing rounds away.
Costing the same month off the dash gives $5.00 per hundred miles. That is 20.6 percent low, and it comes from charging yourself only for the energy that reached the wheels while paying the utility for all of it.
Why the low-mileage car looks so bad
Standing drain is the only loss on the list that does not scale with driving. Keep everything else and cut the month to 200 miles: the driving takes 62.5 kWh, the standing drain is still 12, and the meter figure falls to 97.8 kWh. Real efficiency drops from 2.54 miles per kWh to 2.05, a 19 percent penalty that has nothing to do with how the car is driven.
This is the arithmetic behind the complaint that an EV used for short local trips costs more per mile than the spec suggests. It is true, the reason is standing drain rather than driving, and the fix is either driving it more or turning off whatever is keeping it awake.
Trust the meter over the model
The reconciliation block exists because every field above is an estimate and the meter is not. If a submeter on the charger circuit says 430 kWh and this page says 394, the gap is not noise — it is one of the estimates being wrong, and the standing drain is the usual culprit because almost nobody measures it. Park the car charged, leave it a week, divide the drop by seven, and put the real number in. After that the page is describing your car rather than a generic one.
Questions people ask
How much energy is lost charging an EV?
It depends on how you charge and where the loss is measured. With the defaults on this page, 20.6 percent of the metered energy never turns into miles: charging loss, round-trip storage loss, standing drain and preconditioning, in that order of size. Level 1 charging on a long cord is worse than Level 2, cold weather is worse than mild, and a car that sits a lot is worse than one that is driven.
Why is my electricity bill higher than the car says it used?
Because the car reports energy leaving the battery and the utility measures energy entering the house, with four separate losses in between. The dash is not lying; it is answering a different question. With the defaults the two figures are 312.5 kWh and 393.7 kWh for the same month.
What is vampire drain and does it matter?
It is the energy a parked car uses staying awake — connectivity, cameras, battery conditioning. At 0.4 kWh a day it costs 12 kWh a month, which is trivial against 1,000 miles of driving and severe against 200. Measure your own by parking the car charged for a week and dividing the drop by seven; the figure varies by more than a factor of five between cars and settings.
What does it really cost per mile to charge at home?
That is entirely set by two numbers you supply: your delivered electricity rate and your real efficiency. With the defaults it is $6.30 per hundred miles at 16 cents a kWh. Double the rate and it doubles. This page will not tell you whether that beats gasoline — that depends on the fuel price and the economy of the car you are comparing against, and it crosses over rather than pointing one way.
Should I count the storage loss and the charging loss separately?
Only if your measurement kept them separate. If you compared metered kWh against miles subsequently driven, both losses are already inside that one figure and the second field should be set to 100. If you compared metered kWh against what the car said it gained, that is the charging loss alone and both fields apply. Counting the same loss twice is the most common way this page gets used wrongly.