Electric cars

[Rusty46]

My guest is staying for three months and when I went by the unit I noticed an extension cord running from the outside outlet to their electric car.  What is the airbnb policy on guests charging their cars and not mentioning that they have an electric car...

[Steve4372]

I posted this above.  The calculation is straightforward when you know your KWH power rate.  In short, it costs about $7/day at 20 cents per KWh rate to have someone refueling (charging) their EV from your electricity. ten days = about $70.

Detailed explaination and calculation is below:

It depends on the charger and how much current it is drawing. The NEC (National Electric Code) came out with a limit for EV charging of 80% of circuit capacity. So, for a 15 Amp circuit, the charger should limit itself to 12 Amps. Given that power = V x A, the wattage drawn will be 120V x 12A = 1440W.

Cost will depend on your local electricity rate, not just generation, as some try to claim when trying to minimize the problem, but distribution, taxes, etc. In general, around 20 cents per KWh (Kilowatt-Hour).

The formula for cost is then 1.44 KW (=1440 Watts) times 20 cents per KWh = 28.8 cents per hour. Many EVs arrive needing a good charge so you can assume that they are charging at full capacity while there.

In short, an EV daily charging cost equals 24 hours/day times 28.8 cents per KWh =

$6.91 per day. If they are charging for 10 days straight (feasible using a 120v outlet and still not fully charged) it will cost you about $70.

[Steve4372]

I've replied with the cost calculation in a couple of places in this thread if you'd like to see it.  In short, assume about $7/day.

I believe that AirBnB must address this by allowing easy daily EV charging fees as part of the system if owners decide to allow EV charging from their homes.  A fee of something like $10/day is very reasonable.  It's all based on what your KWh electricity rate is.  You can purchase a 240V EV charging station that allows individual purchases but they are around $1000 plus materials and installation ($1500?) plus maintenance once people start using it.

The engineering side: Where things can go bad is that houses are not wired to continuously charge EVs with the standard 120V circuits.  House wiring circuits are not supposed to be run at full capacity for an period extended time - i.e. at 15 amps for hours on end for a 15 amp circuit.  The NEC (National Electrical Code) came out with a rule recently, requiring EV chargers to limit current draw to 80% of the circuit (15 amp is standard in a home with a few 20 amp circuits in the kitchen, etc).  So, no more than 12 amps for a standard 120 V outlet.  Where you can get in trouble is that many EV chargers can have their current draw set by the user.  They can set the draw to 15 amps (100% circuit capacity), potentially damaging your house wiring while it draws the max for the circuit for an extended period of time.

My rentals book solid with or without EV drivers.  After seeing a couple of people run extension cords up to outlets on my screened porch without asking, basically to steal electricity, fueling their $70,000, plus, EVs on me, I will be disabling those outlets and put in place a no EV charging policy.  There are multiple EV charging stations within a couple miles of my places.  EV drivers can use them just as gas/diesel drivers can go fill somewhere else.  If you don't want to properly fuel your EV and/or want others to pay for it but they won't, don't buy an EV.

To me, it's not about it "only" costing me $7/days to fuel EVs, and the potential wiring damage, it's about people somehow believing that they "deserve" to take fuel from me because ???  They don't deserve to take electric fuel any more that some one deserves to empty my mower gas can into their car when they see it.