Charging At Home

Charging at home is central to your ownership experience–it will be your primary method of charging your car, starting each day with a full tank is one of the perks of EV ownership.

Find an Electrician

The first thing to do is find a good electrician–ideally you want someone who is licensed and has experience installing EV chargers.  Tesla offers a Find an Electrician webpage,  but some owners have reported exorbitant pricing through this service, so be aware.  Other places for references for electricians includes under the Resources tab on our site and though sites like Yelp. If you don’t have a strong lead on an electrician have two or three come out and offer quotes. The electrician will give you three important piece of info:

  1. Whether you have physical space in your breaker box service panel.  If you do, cool, if you do not, the electrician might be able to consolidate other circuits or may recommend a sub panel.
  2. How much spare electrical capacity you have.  A typical CA home has 200 amp service.  Ideally you want to be able to support a 50 amp circuit for your car charger.  Determining if you have the capacity is more than just adding up the breaker values currently in your box  and subtracting from 200.  Instead, ask your electrician for a dynamic load analysis (if he/she looks at you quizzically, call another electrician). The analysis will give you a better idea of how much spare capacity you have, which will determine how fast you can charge. I have 200A service, but I also have a 100A charging circuit because I charge my car at night when there is very little load.
  3. How much it will cost to install your charger.  This is where it is useful to get multiple bids.  You will need to have an idea of where you are planning to park your new car.  Ideally, you want to be as close to your service panel as possible–this will lower your installation costs and increase your charging speed.

If you already have a favorite electrician that might not be up to speed on EVSE installation, refer him/her to NEC Article 625.

Picking a Charger

When it comes to charging equipment, or EVSE, you basically have the three options described below.  I will discuss the max charging speed for each option–your actual charging speed will depend on how much capacity your electrician says you have.  I am only going to discuss 240V options.  Sure you can charge your car off a standard 110V outlet, but, unless you only put a few miles on your car each week, its not a practical solution.  Your electrician will need the info provided below to provide you with a complete installation quote.

NEMA 14-50 Outlet + Universal Mobile Connector

You car comes with a Universal Mobile Connector, so this is the least expensive option and reportedly the most popular option amongst Tesla owners. This setup will charge you car at up to 40A or 29 miles of range per hour and for most owners, this is enough to fully charge their cars overnight. Some owners will buy a second UMC specifically for home charging so they don’t accidentally leave their charing cable at home. Info for your electrician.

Tesla High Powered Wall Connector (HPWC)

This is Tesla’s hard-wired EVSE.  It will charge you car at up to 80A for older Model S or 72A for refreshed Model S and all Model X. which works out to about 50 miles of range per hour. Some owners need faster charging and are willing to pay for the extra speed, while other owners like the fact that is it hard-wired, or simply like the aesthetics better than the outlet/UMC option.  If you have more than one Tesla, you can network HPWCs so they will intelligently share a single circuit.  If you go this route for the speed, make sure you have purchased the on-board charger upgrade for your car, or if you have an older Model S, you should make sure you have the second onboard charger installed.  Info for your electrician.

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3rd Party EVSE

You are not limited to Tesla-branded charging options. There are a number of reputable companies on the market, like Clipper Creek, for example, that make EVSEs that will work with your Tesla and the included J1772 adaptor (more info on what that is in the next section).  If you have EVs from different manufacturers, this is often a good approach, especially if you do not need the speed of the Tesla HPWC.

Charging Options Summary

Here is a handy chart, courtesy of Tesla, that sums up your options.

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Source: tesla.com

Call Your Electric Company

Call your utility for a couple of reasons:

  1. Let them know you are purchasing an EV–this may prompt them to upgrade the transformer and related equipment serving your home (on their dime)
  2. Most utilities have special rates for EV owners.  Its worth your while to find out what those rates are, how to get enrolled and when those rates are in effect.  It can have a significant impact on the cost of charging your car.  Generally, your utility will incent you to charge during off-peak hours

Now is also a good time to consider rooftop solar if you don’t already have it.  As with anything else, shop around.  In the past Tesla and Solar City have had cross-promo deals, now they are under one roof (see what I did there), its always worth checking with them to see if they have any deals.

Notes On Charging

  • There is lots of debate in the owner community on what to set the daily charing level to–Tesla gives you a wide range between 50% and 90%.  If you want to be conservative,  pick a level that meets your daily driving requirements plus a safety buffer.  Personally, I have both cars set to 90% with the logic that if Tesla thought charging the car to 90% every day was an issue, they would not give you the option (if you try to charge your car to 100% too many days in a row the car pops up a warning).
  • If the car detects an anomoly with the charging voltage, it will will back off the charging voltage by 25% but keep charing unless it encounters a more significant fault (in which case it will stop charging altogether, send you a notification via the app and turn the ring around the charging port a suitably serious shade of red).  Do not ignore this “backoff”–have an electrician come and check things out.

Other Questions That Come Up

  • The EVSE and related installation costs might be tax deductible–depends on your particular circumstances, so check with your tax preparer.
  • Make sure you get the required permits  and inspections–either set this up yourself or have your electrician include it in the cost of his/her quote.
  • It is normal for the charging cable and handle to become warm when charing, especially at higher amperages.
  • Don’t plan to use Superchargers for your daily charging–you will earn the ire of fellow owners and a nasty note from Tesla.
  • Plug in your car every day – Elon says so!

 

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