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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?

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 home...it is like having 4-5 gallons in an ICE. That is plenty for the 'after work' drive that typically could be taken.

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!

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

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).

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.

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.

-Josh

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.

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.

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.

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.

Sometimes you can use 2 separate circuits at 110V to get 220V with a special connector. http://www.quick220.com/220_volt.htm

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?

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.

@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.

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?

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?

@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.

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

@Hodas

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.

@jat

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?

@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.

I have a 60 and routinely do 100-130 miles in a day, sometimes 180.
The longest my car has charged is 5 hours.

The other day, I had drained the battery down to 30 miles, had to do a 50 mile loop after work, so I came home, plugged in for a half hour into my NEMA 14-50 and was good to go... (8 miles left at the end , the closest I have ever pushed it).

Yes you definitely need the HPWC. As a matter of fact, you should buy mine!

So far it is the only thing I wouldn't buy if I had it to do over again. 9000 miles total with an 80 mile commute and I haven't had an occasion where it made a difference yet.

@pbendo - how much do you want for it? :)

@jat

"125V * 12A * .86 / 265 Wh/mi = 4.87 ideal mi/hr"

Here is how I am interpreting these numbers: The 5m/h charge claim is at 110v, not 125, an immediate > 10% difference. The .86 is represents the 13% Amped mentioned, right?

265 Wh/mi is indeed roughly an ideal ("minimal") cost per mile driven - I am running just over 300.

But how is Wh/mi related to time-to-charge? I can see that it determines how many miles I'd get from some amount of electricity under ideal conditions. I'm not asking how many miles of any sort I can go, I am asking *how long does it take to get from N miles of rated range on the speedometer/powermeter to "Full"?*.

When a car is plugged in the Wh/m is either 1) not in the equation (if it measures only energy spent, as above) or else 2) the Wh/m factor of rate-of-charge is "ideally" accurate and some other factor is not living up: the simple fact is that the cars own measured rate of fill is about 2/3 of teh number they publish without any qualifications:

Sample deltaT deltaM m/h (the 5280' kind)
1: 9h25m -> 32m 3.4
2: 14h10m -> 46m 3.3
3: 7h -> 22m 3.1
4: 13h44m -> 44m 3.2
5: 18h30m -> 60m 3.2

I gathered these using this method: at the end of a drive I record the rated miles and start time, then I look at the same when I return to the car. If the car is full I toss the data out as I'm not sure when it reached full. If its not full, I record. The electricity has been flowing the entire time - and rate-of-fill is roughly 2/3rd what I used as a factor in my purchase decision.

For what its worth, I'm satisfied with my rate - because I took my absolute need and doubled it before deciding. At 66% of expected I have only 33% more than my need, and not a lot of flexibility. The rate-of-charge is by far and away the one thing that falls quite-a-lot short of my expectations for the car.

No doubt people will clamor about ideal miles. I'm fine with that, so log as Tesla adds the same kind of warnings about ideal miles to their rate-of-charge numbers as they do to the rated-vs ideal miles/energy-spent estimates. I saw the warnings about those. I use a 2/3-of-rated limit on my range, and I can accept a 2/3-of-rated speed of charge too. But that's me, and people ought to be able to decide for themselves from numbers that are clearly described.

If Tesla clarifies their rate-of-charge numbers, I'll be even more HAPPY WITH MY MS.

I suspect the vampire drain is such a high percentage of the 120V feed that the 5 mi/hr is cut down to 3 by it.

@david.chenney - it matters because you can configure the car to show ideal miles or rated miles. Up to 300mi range, 5mi/hr charging rate, etc are all in ideal miles. If you have your car set to display rated miles, then obviously the mi/hr charging rate is going to be lower because it takes more Wh going into the battery for each one of those rated miles.

HPWC is unnecessary. I have it but not quite sure why. Used the 240v while my HPWC was on backorder and that worked like a charm for my type of daily commute, @ 25 miles round trip. If I had it to do over, I would just install some type of garden hose bracket to keep my power cord off the floor of my garage for a neat storage solution. Will not install another HPWC when my wife gets her Model X.

Yes you will, if you want it to come with twin chargers!
;p


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