20 mile daily commute: do I need HPWC?

20 mile daily commute: do I need HPWC?

My daily drive to work is only 7 or 8 miles. At lunch I typically go somewhere close by to eat. So an average daily commute for me is only about 20 miles. The Tesla website suggests I would be fine just plugging into the 110 V outlet in my garage. What have other people with low mileage commutes found? Is it OK to get the car without the HPWC?

gasnomo | 31. Juli 2013

HPWC is unnecessary.

Colasec | 31. Juli 2013

I have a ~30 mile daily commute and have been getting along just fine without the HPWC.

You should get a NEMA 14-50 outlet installed though. There's plenty of information about that on the Tesla site (Model S > Charging) and on these forums.

emd1234 | 31. Juli 2013

I drive over 100 miles a day, and would be just fine without the HPWC. A standard dryer outlet (220V) would be just fine. I did get the HPWC "just in case" and have found it to be handy once, but generally I would be fine without it.

A 110 V outlet will get you about 4 miles/hr charge. If you charged 10 hours overnight, you'd get around 40 miles charge. But, once you get your car, you'll probably find yourself driving more than just the 7 or 8 miles each way to work.

jeffaa | 31. Juli 2013

Twin chargers are also unnecessary.

nickjhowe | 31. Juli 2013

No way do you need the HPWC. If you are getting a 60kWh car, plan to do 100+ miles, come home and then go out a few hours later then maybe.

For you....
20 miles at c. 350Wh/m is 7kW. You could loose about 3.5kWh from vampire drain. So 10.5kWh

Assuming you charge from 6:00pm to 8:00am (14 hours), with 120V at 12A will give you about 17kWh after charging losses.

So you should be good to go. But be warned - some people have reported that 110V at 12A can barely keep up with the vampire load on the car sometimes. If you wiring is not good, or if the heat/cold is excessive you either won't get 17 kWh, or you'll use more than 10.5

If you have room on your panel I'd drop in a NEMA 14-50 outlet, even if you can only run it at 20A you are going to get 57 kWh - or 5x what you need.

EJH | 31. Juli 2013

Although it is probably not an item that more than 2% of owners would ever need, it is still a cool item to have. In Ontario, we receive a $1000.00 credit for the EV electrical hookup, but it must involve an approved EV charging unit such as the HPWC.
This reduces the cost by a grand, so it is an easy decision to make.

AmpedRealtor | 31. Juli 2013

You also get a federal tax credit equal to 30% of the cost of the charger. This credit falls under installation of EV charging infrastructure and is applicable to residential EV installations. So spending $1,200 for the HPWC gets you back $360 in federal tax credits. A tax credit is not like a deduction. A tax credit reduces your tax obligation, a tax deduction is a reduction in your taxable income.

Docrob | 31. Juli 2013

14-50 with a single charger would be more then adequate. You could scrape by with a 110v however if your driving pattern changed it would not be enough, it would certainly do initially whilst waiting for a 14-50 installation.

dbrooks | 31. Juli 2013

I would also say no. I have an 80 mile round tripper daily. I can charge at work on 110, but I never seem to need the extra charge. Actually I go all week charging at 110 at work, then charge at home the last night and repeat. My range has never dipped below 100 miles (85kwh).

yodasminion | 31. Juli 2013

I would second everything already said here. I have a 50 mile commute one way, and I'm not getting twin chargers or a HPWC. A 14-50 Nema outlet is all you need. The superchargers bypass all onboard charging systems anyway.

SCCRENDO | 31. Juli 2013

100 mile daily commute. Have a 14-50 and regenerate my losses in 3-4 hrs. Have only charged outside my home to try it out such as Hawthorne supercharger and Ontario airport but wasn't needed. Have a 220 mile day trip coming up so I will likely get a top-up somewhere for security.

create | 31. Juli 2013

@amped the tax credits for ev charge station I believe don't work if you pay amt which I would guess a good number of folks that buy Teslas fall into. Unlike the EV tax credit which does work for all.

David70 | 31. Juli 2013

If you're only doing 20 miles round trip each day, you could even get by with 120V, 12A. But I'll still recommend putting in a NEMA 14-50 outlet. | 31. Juli 2013

The 30% tax credit also applies to your NEMA 14-50 installation (It is after all an EV charging station that would otherwise not be in your garage)

Bighorn | 31. Juli 2013

Haven't gotten my 14-50 wired yet, so I've used the 120V outlet without a problem despite giving about 100 miles of test drives a day this first week of ownership. Normally I'd commute 40 miles a day and would foresee no problem using the 120V plug. I'm consistently adding 4 MPH charge.

Windsurfer | 31. Juli 2013

Thanks for all of the responses. Sounds as if it makes sense to forego the HPWC for now.

One question: if I'm charging off of the 120V outlet, what is the advantage of getting the 14-50 NEMA circuit wired? Does that allow for higher amps? Please forgive my ignorance as this is new to me.

Bighorn | 31. Juli 2013

120V adds charge at 4 miles per hour while the 14-50 will go about 29 +/= miles per hour.

Cattledog | 31. Juli 2013

NEMA 14-50, single charger, smile, enjoy.

NEMA 14-50 is a 220/240v outlet with a 50 amp breaker, your car will draw up to 240 volts and up to 40 amps current, which will translate into the 29 miles/hour for range.

Think of it this way - with a completely depleted battery, you can recharge overnight with a NEMA 14-50 (approx 8-9 hours). With just about any 120v outlet, it takes 2.5-3.5 days.

Go NEMA 14-50 and no regrets.

Brian H | 31. Juli 2013

I know of one owner who has a single charger, but got the HPWC anyway because of appearance and freedom from attaching the UMC every time he charges. Looks and convenience.

earlyretirement | 31. Juli 2013

I seriously doubt you will only be driving 8 miles per day in this car once you get it. I have a friend like you that didn't drive much at all before. Now he is driving over 75 miles a day as he always finds an excuse to go run errands. LOL.

jchangyy | 31. Juli 2013

I agree with everyone. I drive ~16 miles daily and doing fine with NEMA 14-50 installed. In fact, I only charge every 3-4 days.

ir | 31. Juli 2013

I have a similar commute and using 120V at work ALMOST covers the round trip (ie. I don't even need to charge at home). I have a 14-50 outlet installed for weekends and to top-off at the end of a weekday.

I strongly recommend something more than a 120V at home for weekends and the odd surprises. For comparison, a 14-50 is slightly faster than most public EV chargers.

nickjhowe | 31. Juli 2013

@Windsurfer - in the Model S delivery checklist and owners guide there's a section about setting up charging at home, and links to TMC where there are some very detailed instructions for you or your electrician if you choose to go that route.

mreitman | 31. Juli 2013

Put in a 14 - 50. You won't need the HPWC but you will find that the c at is so much fun that you take detours to and from work. Nice to always know rhat you can recharge overnight.

bfranks273 | 31. Juli 2013

So, per all the above, you see that the 14-50 when properly installed gives you about 10KW which matches your single charger. If you get home with zero miles you can fill it up in 8 hours. The HPWC is double: 20 KW, requires dual chargers in the car, and you can charge an empty car in 4 hours. Just a factor of 2. Will you ever need it? Maybe once.

But another thought for you, if its a long wire run then that is where all the cost, time and effort is. You might run larger cable so that in the future you can upgrade without having to run the cable again. But really, 20 miles a day is 8-10 kWh which will take about an hour.

( but 5-8 years from now, when the cars have 500 mile batts, and your job moved way out, and you have 3 EV's to charge at once...)

Cattledog | 31. Juli 2013

If you have time-of-use electrical rates (generally meaning your utility charges different rates during different time periods of the day) then having a 14-50 will likely allow you to charge within the most favorable rate window.

120v, not so much.

Brian H | 01. August 2013

And if the TOU window is made really small ...

aaronw2 | 01. August 2013

I drive 40-50 miles daily and currently am using a NEMA 14-30 outlet and so far it hasn't been a major problem. I do have a HPWC and am just waiting for the electrician to upgrade my service panel (for PG&E E9-B) and run a 100A circuit to the garage for it.

dortor | 01. August 2013

HPWC is un-necessary for your "planned" needs - however a NEMA 14-50 is useful for times when:

a) you need to drive the car further
b) want the turn around time to be practical

I would recommend having at least a 240v/30-50 AMP circuit that when needed you can use the car's full range and not have to wait over 8 hours for it to be back at full capacity…

dtesla | 01. August 2013

In you case I agree the NEMA will meet your needs. If in the future your needs changes you can always buy the HPWC for the same price online as with the car(at least the same price today).

TrojanTesla | 01. August 2013

I have an 85 and installed a 14-50. I drive 120-130 miles per day, only charge up to 240 miles at night and usually have at least 100 miles of range when I get home. I start charging at midnight when the TOU super low rates kick in and charging usually takes less than 5 hours.

I originally wanted to get the HPWC with twin chargers and Tesla advised against it based on my schedule.

If you think this way...with 100 miles left when you get is like having 4-5 gallons in an ICE. That is plenty for the 'after work' drive that typically could be taken.

Bubba2000 | 01. August 2013

I has a HPWC installed with a 100A/240 circuit. It was a challenge. The Siemens circuit breaker box with 200A feed was on one side of my 2 car garage with 2 doors. I wanted the HPWC installed on the wall between the 2 garage doors. Also, the breaker box has no open slots.

First the electrician had to replace 4 single beakers with doubles to make room for the double size 100A breaker. That was $20+$20+$49. He chose to use 2 gauge wire that is rated for 100A and 125A Max. Chose tray quality cable that had 2 lives, 1 neutral and an extra ground that was not needed. That was one fat cable that cost $8/foot and I needed 32 ft. Plus $25 in conduit to enter and exit the cable. Installation was a little tough to manage the cable on bends. Took about 5 hours till the HPWC was installed.

The HPWC works great and is very convenient with the 85P/Pano/Pearl/Grey/loaded, dual chargers, etc. Do I really need it? No! I got the car set to charge at 30A only. Heck, I did not even need the car. However, I put my savings in this stock between $35-40 after testing driving a friend's SigP. Talk about being impressive. I am more impressed with my 85P. The quality has improved with tighter tolerances, finish, etc. Doors close like a Mercedes!

DTsea | 01. August 2013

If you only drive 20 miles a day you don't even need 240V charging, a 110 socket would charge it in 7 hours.

kafahsholtz | 01. August 2013

My wife commutes about 50 miles a day (round trip). The 240w/50 AMP works great. We've put over 9,000 miles on the car in 8 months, had 0 range anxiety or problems. She forgot to plug it in for a couple of days and didn't have any problems (though she was irritated when I told her to after noticing the low remaining miles while on the other side of the country - the Tesla app is great).

JoeBadge | 01. August 2013

I walk to work, but have managed to put 4k+ miles on my car in the past four months - 'joy riding' for any excuse I can get after work hours. To that point, I have a 240V at one house and a HPWC at my condo. I do most of my 'riding' on the weekend, and it's very reassuring that I can stop by the condo and get a fast charge while I eat dinner. While I can use a 120V during the day while my car is parked, it's good to have the option to 'fill up' fast as you plan your next adventure.

Hodas | 07. August 2013

As everyone has said, even factoring in what I am about to say, you can almost certainly get by with 120v/12A service.

But be aware that if your 7-8 mile commute each way is in city traffic, your drain will be significantly more than 7-8 miles of range each way.

My average daily commute is about 5-6 miles total (1.5 miles each way plus a short sidetrack or two for errands). But I live in downtown Los Angeles and average 560-620 W/mi on that daily drive, vs about 360-370 overall average when you add in my weekend long-distance driving.

Stop and go traffic is brutal on the power drain, using about twice the rated draw.


rsmits | 07. August 2013

I do about 25 miles a day. I just plug in to 110 overnight and I'm fully charged in the morning. I get about 4miles an hr charging. We needed to do a major overhaul to get 14-50 in our detached garage.
We did one road trip over a weekend where we returned home with 10 miles, it wasn't until Thursday did we get a full charge back during the week with our regular driving.

Anonymous | 07. August 2013

I agree with JoeBadge, I find excuses to drive. I try not to eat close to home anymore, I try to find something with a little drive.

Earl and Nagin ... | 07. August 2013

I'll echo those who say you don't NEED an HPWC for a 20 mile daily commute.
However, it can be nice to have but here's another option that I find to be very useful:
We started with a NEMA 14-30 in our garage for the first 2 years with our Tesla Roadster, then we sprung for a Clipper Creek CS-90 (70 Amp, 240 Volt J-1772) charging station that will charge any modern EV as well a Tesla with adapter. Only Teslas can handle the full 70 Amp current though.
I'd say we've found the 70 Amp capability to be useful only about 5 times in the past 2 years that we've had it. That was for times when we'd been driving a lot during the day, then wanted to quickly get some range before going out for the evening.
Summary: Its a nice-to-have luxury but not absolutely necessary.

david.cheney | 07. August 2013

I currently live in a place where I'm really only able to get 110v service and so I looked carefully at charge rate. Tesla claims 5 m/h of charge at 110v 12 amps. 12 amps total is what a typical 15amp circuit can sustain.

My calcs went like so: I commute 20 miles total per day. Double it for plenty of safety.. 40 miles. At 5 m/h it needs 8 hours to charge. By that calc I can pull in at 11 PM and leave at 7am and always keep a full charge. Sweet.

If I want to go on a longer ride (and likely you will :) it could take a while to catch up, and I've also got an ICE as a backup for road trips and such (if you don't that makes you dependent on pretty limited charge speed at 110v).

Bottom line for a twenty mile commute along with sporadic longer trips and alternative transport: its a breeze!

Well yeah, except that, in practice my car while telling me that it is charging at 108v 12a and is getting barely more than 3 m/h, so my 'safe' 40 miles now takes 13+ hours to recover and suddenly we are in a whole new game.

It turns out that I really don't often drive more than ~30 miles per day so I'm glad to say I'm fine. Now, if I wanted or needed to every day drive 40 miles, I'd be in trouble and I'd be pissed. And of course it would give me more flexibility if I actually got the claimed 5 m/h.

Before a brief rant, let me assure you I love my MS....

It seems EVIL to me that Tesla still claims an unqualified 5 m/h at 110v/12a (see Outlet Charging - Adapter Guide) I really dislike it when someone establishes an expectation and then come up 40% short. If an ICE car manufacturer claimed 30mpg and delivered 18, I suspect courtroom drama would be in their future. C'mon Tesla!!

I don't like my charge rate, but I am still LOVING MY MS.

Brian H | 08. August 2013

Sometimes you can use 2 separate circuits at 110V to get 220V with a special connector.

Hodas | 08. August 2013

Yes, similar to @david.cheney I consistently get 3 or sometimes 4 miles per hour of charge on 120/15 (which reports 114-117V in practice once charging starts).

Can anyone tell me what I would get in practice if I did have the maximum 240v installed that will work with a car that does not have dual chargers?

dortor | 08. August 2013

5 miles/hour is "ideal" range - not rated range - 3 mph is "rated" range…you may be able to upgrade you 120V circuit to 20 or 30 AMPS - at which point you'd get 4-7 mph rated range…

the new Tesla 5-20 adapter allows charging at 16 AMP off of a 20 AMP 120v circuit.

jat | 08. August 2013

@david.chenney - The 5mi/hr charging rate at 120V is ideal miles, not rated miles, and assumes a full 125V (just like the HPWC at 10kW assumes 40A@250V).

Just like when I bought my LEAF (which is now my wife's) -- the claimed range is 100mi and the EPA range is 76mi, and I looked at what those estimates entailed and figured the way I would drive it I would get about 65mi. That estimate turned out to be exactly correct. So bottom line, any marketing numbers are going to generally have best-case assumptions built in, and you should understand those before you make decisions based on them.

AmpedRealtor | 08. August 2013

I'm a little confused on the numbers, how can 5 MPH be ideal range but only 3 MPH for rated range?

If you look at Tesla's battery ratings, ideal range is only 13% higher than EPA rated range. 300 miles versus 265 miles. So while charging, shouldn't the same math hold true? If you are charging at 3 MPH in rated range mode, ideal range should only be adding another 13%. The difference between rated and ideal should be 3 MPH vs 3.4 MPH.

How can there be a 67% disparity between rated and ideal range while charging, yet when the battery is full there is only a 13% difference?

jat | 08. August 2013

On a similar note -- when they say "up to 300mi range", did you assume that you could drive how you wanted and achieve that, or did you investigate what you were likely to get in real-world scenarios?

jat | 08. August 2013

@AmpedRealtor - 125V * 12A * .86 / 265 Wh/mi = 4.87 ideal mi/hr

118V * 12A * .86 / 308 Wh/mi = 3.95 rated mi/hr

In the marketing materials, they round up, while the car truncates the fraction when showing you how fast it is charging. You can calculate the actual rate the car is charging by looking at how long it takes to charge.

AmpedRealtor | 08. August 2013

@ jat - thanks for explaining the calculation, I knew someone with math skills would jump in! :)

PaceyWhitter | 08. August 2013


If you installed a NEMA 14-50 outlet you would get 28-30 miles of charge per hour. Dual chargers are only used with the HPWC at home.


You math seems good, but Tesla does lable the 5-15 outlet as a 110V outlet. Why do they do the math based on 125V?

jat | 08. August 2013

@PaceyWhitter - Because depending on the electrical system, you actually get anywhere from 108V to 125V. The ~120V is actually the delta to ground from one of the hot lines of the split-phase ~240V system in which case it is close to 120V, or the delta to ground from two phases of a 3-phase system (commercial sites, including some multifamily residences, will use this) in which case it is under 110V. Generally this is pretty sloppy, as people refer to it as 110V or 120V -- at my house, it is typically 122V. 240V is even worse, because if it is 2 legs of a 3-phase system, it will be about 208V (beware a number of public chargers are 208V, so you will charge slower than you expect).

These days, most devices are built to auto-range for anywhere from 108V to 250V, and that includes the UMC. However, the total power is volts * amps (ignoring the power factor), and the current is limited by the size of wire and other components. So, if the voltage is lower, you just get less power as you can't just draw more current to make up for it.