I currently get 4.5 mph off a NEMA 5-20. However, that's at an abysmally low efficiency of 79%. If the 3rd gen battery/charger can solve these efficiency issues, then you can get an appreciable charge rate. My napkin math shows if Tesla can achieve 95% efficiency with 215Wh/mi then the charge rate will be ~8 mph. There is another reason why this is important, because with the Model 3 release Tesla will be adding significant amounts of battery storage to the grid. It makes sense for this battery storage to be plugged in during sunlight hours, when people are at work. Installing NEMA 5-20's for many parking spots is much easier and cheaper than installing EVSE's everywhere.

Battery storage? You're not making much sense. Depleting the battery so people can't get home at the end of the day. Increasing the wear and tear on the battery causing degredation.

Why would you not be able to get home at the end of the day after charging all day basically on solar power? There are two problems, increasing solar power without the ability to store it, and increased load on the grid from charging cars. Of course if you do them at the same time there isn't a problem. You're thinking of something else.

^ I agree- I was wondering initially what this was all about and am still lost on the battery storage concept. I guess the charging concept is that the current 110V charge is slow at 4.5 miles added per charge hour. So a 12 hour charge results in about 54 miles of range being added to the Tesla. If Tesla were to improve the efficiency, it could become 96 miles per 12 hour charge or just under 1/2 the M3's projected range. Even with the 'efficient' charging in place, I think most people will want to go with the 220V charge option- it did not take me very long with our Nissan Leaf to go that way. The M3 makes it even more compelling since you will have an even bigger battery to charge.

Just saw the additional info now- so the 110V would be sort of a trickle charge idea for keeping the energy grid healthy? It would not solve the other problem about having a real charging solution for anybody with a long daily commute.

For home charging maybe. However installing a parking lot full of NEMA 5-20's is WAY cheaper than installing a parking lot of NEMA 14-50's. You can install 2.4x as many outlets for the same supply, so all ev owners can simply come to work and plug in all day, and not fight over charging spaces, as well as deal with those few anti-social ev owners work park their cars at the L2 charger for 2 days at a time.

Point 1 is it won't be so much of a trickle for the Model 3. Point 2 is at 72 miles charged over a 9 hour workday, something like 98% of all commutes would be covered, and then some. I happen to get just over 50% of my energy from 5-20 already now. It doesn't matter that it's slow, the car is parked all day and it is free.

You didn't say anything about solar power. So charging at peak rates didn't make any sense to me. Therefore I was assuming you were talking about feeding back into the grid during they day, depleting the battery.

In a California thread there is a discussion about Ohmconnect. Ohmconnect can tell your Tesla to ramp down charging if the grid is being stressed, like in late afternoon when solar ramps down. Conversely in California there is concern about so much solar generation that the grid will be stressed by overgeneration. I can see Ohmconnect evolving to tell a Tesla or any connected device to ramp up charging during the latter example to add load. At 110 volts it would take thousands of Tesla's to make a difference but the concept is a good one and there may be incentives to install many 240 volt EVSEs if they could help manage the grid.

Regarding Point #2: how confident are you that the 9 miles per hour charging will be reality? If it's not, then there are lots of people who commute 40 miles to work and they might even take their car to lunch so that could reduce charging time by an hour. The other point is that maybe charging isn't always free at all places and it might make more sense to charge in 4 hours at 220V and give the charging space to somebody else. It's a little early to think that employers are going to roll out dozens of charging spots. My employer supplies two for a company with 500+ people.

I think it could be 8, based on some educated guessing. It will clearly be better than 4.5. It's pretty much 5 on a 70D right now already. You don't have to fill up at work, you'll have 215 miles range minimum. Even if daily charging is short, you may only have to charge at home once every few days to catch up. There are a few people that live with 120V charging with Model S now, clearly this will be more feasible with Model 3.

isn't the point of it to be able to get plugged in EV's to take the energy when it suits the grid rather than when they are timed to take it? So if we have the opportunity to get charge when solar (cheap) energy is available it would be beneficial. That still has to be balanced with whenever peak loads occur, in sunny climes that tends to be when the sun is high anyway. Solar on its own doesn't handle the early evening peak though and thats where the return from EV's can help, acting like a huge distributed battery. The problem is that most current EV's don't really support that.

Just to add a bit, here, there is also the issue that 120v charging takes a LONG time, and is also a lot more expensive. Tesla's own charge calculator makes the case pretty clear: 200 mile charge, using NEMA 14-50: 6 hours 48 minutes, 66 KWh, and $19.80 cost at .30 / KWh (California tier 4 residential pricing) 200 mile charge, using 120v: 61 hours 24 minutes, 88.4 KWh, and $26.52 cost at .30 / KWh (California tier 4 residential pricing) It's a big difference.

You must have missed the first post where I detailed the efficiency issue, and also that this is the Model 3 forum, not Model S. Since we know that most of it appears to be auxiliary overhead and not simple step-up losses, chances are pretty good the Model 3 will achieve high efficiency at 120V.

Hey I hope you are correct. I was simply sharing what the state of affairs is now. From what I've read, the auxiliary overhead you mention is about 340+ watts per hour currently. That value, when multiplied by the number of hours to charge to a given level, yields almost the entirety of the power consumption differential between a 240v and a 120v charge. Now, if Tesla were somehow able to reduce the auxiliary drain by 50%, what would that do to charge time? Not that much. Again, if we look at the current numbers, it would boil down to a consumption differential of about 10 kWh. That would, on the standard circuit, be a difference of about 7 hours. So the charge time would be 54 instead of 61 hours. Again, that's doubling the efficiency of the car while charging. The real question is how much more efficient will the Model 3 be than a Model S during operation? So presume for a moment that it could somehow be a lot more efficient. Let's say, for example, that it is almost twice as efficient, and that it can go 215 miles using only a 40 kWh battery. Let's also say that it can charge with twice the efficiency, only using 170 watts per hour overhead. So, with a standard circuit, it would 'cost' 44.72 kWh of electricity to charge that battery, and it would take 31 hours. That would work out to a charging efficiency of 6.93 miles per hour, which is certainly not bad. So, is that doable? Can they build a car that is twice as efficient as the current models? I guess we'll see.

Sorry for off-topic, is the charge calculator still available? Had it open in browser while they did the Model S refresh and the calculator has been MIA for me since. If it is available, can you give the link? Thanks.

Is there a time problem in OP's efficiency calculations (and in Tesla's)? The 120/16 charge calc includes 61 hrs of phantom drain, the 240/40 does not. If you include an additional 55 hrs of phantom drain in the 240/40 then will both effectively use the same kWh and cost the same? BTW, at the house we use in Marco Island we have only a 120/15 in the garage and with one exception (thanks Richard!) that was sufficient for 3 months.

They are have some coefficients. Code: coefficients_US : { standard :{ time : 0.307, energy : 0.442, cost : 0.05 }, nema_30 :{ time : 0.058, energy : 0.336, cost : 0.04 }, nema_50 :{ time : 0.034, energy : 0.33, cost : 0.04 }, hpw_single :{ time : 0.034, energy : 0.33, cost : 0.04 }, hpw_double :{ time : 0.017, energy : 0.329, cost : 0.04 } The part I am unsure about is the time coefficient. The energy one is straight forward, Later on in the js they are multiplying the miles driven be the energy value to get the kWh used, but I am unsure where the time part comes in. Code: setInterval((function() { var c, dm, kc, kwh, m, tc, i18n_kc; dm = parseInt($("#daily_mileage").val()); //get time coefficient for the region cTime = _this.getLocalTime($("#charge_mode").val()); //get cost coefficient for the region cCost = _this.getLocalCost($("#charge_mode").val()); cEnergy = _this.getLocalEnergy($("#charge_mode").val()); m = Number($("#charger_config").val()); if (c !== 18) { m = 1; } else if (c == 18) { c = 9; } c = c * m; //energy calculated //kwh = (dm * 283) / 1000; kwh = dm * cEnergy; //time calculated t = dm*cTime; //cost calculated kc = dm * (Number($('#kilo_cost').val().replace(/[^0-9\.]*/, ""))*cEnergy); if (("" + kc).split(/\./).pop().length < 2) kc += "0"; $("#time_stat").wf_datalabel("value", "" + (_this.timeFormat(t * 3600))); $("#cost_stat").wf_datalabel("value", global.Tesla.Calculator.localizedCurrency(kc, global.Tesla.Calculator.localeSettings[locale])); return $("#kilowatt_stat").wf_datalabel("value", "<span>" + (Number(kwh).toFixed(1)) + "<span class='sml'>kWh</span></span>"); }), 100); $("#daily_mileage").change(function(evt) {}); return this; } https://www.teslamotors.com/sites/all/themes/custom/tesla_theme/js/models-charging/calculator.js I am not sure the 340wH(240V) and the 440wH (120V) are overhead, since that implies there is an additional cost for charging that isn't present.