Wow, there's a reason for the twin chargers I didn't even think of. One never knows when an electric company may come out with something like that. Makes you think about the resale value of the twin chargers, too. I wonder why the sales reps (configuration specialists) are so anti-twin charger...mine was too.
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Wow, there's a reason for the twin chargers I didn't even think of. One never knows when an electric company may come out with something like that. Makes you think about the resale value of the twin chargers, too. I wonder why the sales reps (configuration specialists) are so anti-twin charger...mine was too.
Oh, I totally missed that. I was thinking you needed the dual chargers to supercharge. It looks like they're natively DC and don't use the on-board chargers at all? For me it still makes sense. If we knew for certain that you could easily add a second charger in the future then for most people at this point a single charger is likely sufficient. Unfortunately I don't think we know that for sure. It reminds me a bit of heated seats on Porsche 911's convertibles. It's a $500 option, and you frequently see FL and TX cars without heated seats. Unfortunately saving that $500 at purchase time significantly limits the pool of prospective buyers when it comes time to sell it. Penny wise and pound foolish.
A
It makes me wonder if there isn't a little reverse psychology at play here. Just about any sales rep I talked to downplayed the whole performance option and the HPWC. seems just about any time I talked about an upgrade, they did the reverse of a typical salesman and played it down or were neutral. In retrospect the soft sell is good, because in the end after months of removing this, adding that, removing everything, then adding everything, we ended up with everything but the paint armor and there is no one but ourselves to blame :~).
Vger
Active Member
Actually, you need a 100A circuit to fully utilize the HPWC. The breaker needs to be 25% higher than the current you want to draw from it (80A).
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My take: If you live on the west coast or in Canada, you have dozens of 70A Clipper Creek EVSE's to use on road trips, so twin chargers are great. if you don't, it is possible you will not use the second charger much, unless you have another reason to have an HPWC at home, like @andrewket.
I have seen the wiring on the chargers on the car, and the inside of the primary charger, because my car had an early (resolved) hardware fault there. It may be possible to add the second charger later, but it will not be easy, and therefore it will be expensive on labour. {I am not posting the photo, because Tesla might consider it quite proprietary.)
Also, I can confirm that there is NO "fail-over" capability between the two chargers. The "primary" charger has other stuff in it, including the DC-DC convertor that charges and powers the 12V system. The boxes do not even look remotely the same. There is obviously a module inside which is common, but the whole assembly is different between the two.
smorgasbord
Active Member
The math doesn't quite work out, though. You're spending $1500 on the second charger, $1200 on the HPWC, and hundreds on the upgraded wiring. I'll do you a favor and drop out the wiring upgrade cost.
First, let's look at the charging window of 4 hours. On a UMC, that will give you about 124 miles of charge. If you drive less than 120 miles a day and start charging at 1am, you'll be done by 5am even if using the UMC. So, on how many days a year do you drive more than 120 miles? If you're driving 120 miles every weekday, then you're already driving 21,000 miles a year. If you're not doing more than that, you're not saving any money.
Now, let's look at your potential savings. To maximize your savings, let's start with a high normal rate of $0.50/kWh. So, 76% of that is $0.38/kWh saved. You'll need to consume 7,105 kWh to pay for the $2700 additional cost. That's about 21,000 miles at 12.7 cents/mile saved. So not even 13 cents per mile for each mile over 120 that you drive in a single day.
QED
PS: Note to Mods - can we merge this into the previous thread from a year ago that I referenced a few posts earlier?
According to their website, the Clipper Creek high power charger does 18 KW. I plugged into the Gilroy charger which charged me at 22 KW. That's low for a supercharger but I only stayed plugged in for a minute or two so I suspect thing were still sorting out. But at 22 KW, the recharge rate was about 1 rated mile per minute which is faster than the Clipper Creek EVSEs.
My take: 20 KW isn't fast enough on road trips to make it worth buying the second charger. If you're close to empty, charging at 20KW means you drive for 60 miles than charge for an hour. Repeat.
Yuck. Unless you've got lots of patience on road trips, the second charger is better thought of as a range-extender to grab an extra 30-60 miles than a real road-trip enabler.
The pattern for an SC when paired with the 85KW battery pack is more like drive 140-160 miles. Charge for about an hour. Repeat. The problem is that the SC can't charge at full rate the entire time. So if you want faster charging, you need to drive a long first leg to drain most of the battery pack, then charge the pack only part way for the rest of legs between charging.
That pattern is more like drive a first leg of 160-180 miles. Then charge for 30 min, drive for 90 miles, repeat.
So the supercharger + 85KW battery is a barely adequate road trip enabler in my opinion but it's a heck of a range extender if you only need an extra 30-150 miles.
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Al Sherman
It's about THIS car.
In 5 years with the Prius I can count on one hand the drives that were over 200 miles round trip. I've never driven it over 5000 miles in a year. I can't remember ever going over 80 mph.
I'm getting the Performance with Twin Chargers and the HPWC. I don't think you can justify even the cost of the car much less the extras for the chargers and HPWC. If I was trying to justify cost I would already have the Leaf. I'm getting it all because this car is a stunning achievement. This is not the final answer, but I want to be on board at the highest level possible for the whole ride.
I'm getting the Performance with Twin Chargers and the HPWC. I don't think you can justify even the cost of the car much less the extras for the chargers and HPWC. If I was trying to justify cost I would already have the Leaf. I'm getting it all because this car is a stunning achievement. This is not the final answer, but I want to be on board at the highest level possible for the whole ride.
I agree RCC. I can see 500-700 mile days w/o enormous hassles.
Start 265 at 9
drive 200 miles stop for lunch, supercharge
leave with 200+ miles at 1, drive 150, stop for coffee and stretch (this where it comes undone for me, I don't do 1 hr. stretches)
leave with 200+ miles at 4, drive 150, stop for the day (500 total) or stop for dinner and do a last leg that takes you to almost 700.
My wife and I have driven 770 miles in a day, San Antonio to Santa Fe, in under 10 hours. Only 300 miles is I-10. Even if I could hand pick supercharger locations on I-10 and New Mexico State roads, it is at least a 13 hour trip in a Tesla.
Range Extender until 10-15 minute full recharging is ubiquitous. We're a generation away from that.
Start 265 at 9
drive 200 miles stop for lunch, supercharge
leave with 200+ miles at 1, drive 150, stop for coffee and stretch (this where it comes undone for me, I don't do 1 hr. stretches)
leave with 200+ miles at 4, drive 150, stop for the day (500 total) or stop for dinner and do a last leg that takes you to almost 700.
My wife and I have driven 770 miles in a day, San Antonio to Santa Fe, in under 10 hours. Only 300 miles is I-10. Even if I could hand pick supercharger locations on I-10 and New Mexico State roads, it is at least a 13 hour trip in a Tesla.
Range Extender until 10-15 minute full recharging is ubiquitous. We're a generation away from that.
ClearwaterBchSteve
P445 / VIN 1794
My P85 does not have a 2nd charger, but I am somewhat wishing I did purchase it with the car. Other than the jump-seats & paint armor, it was the only option I didn't get.
I now am hearing that even though it can be added later, it will cost 2 - 3 times more than if it was added during original build - that might change in the future as more people opt for the upgrade, but for now it's somewhat of a custom job.
The 40A 14-50 is certainly adequate for my day to day use, but having the extra capacity on road trips could be beneficial. Most likely there will be more high-power chargers (in addition to the super chargers) on the highways in the coming years. However, if enough super chargers are installed in the right locations, then I will have made the correct choice - time will tell.
Another possibility exists that some type of "home" semi-super charger might become available that would bypass the car's internal chargers using the same method as the large scale versions on the roadways... Unfortunately, I don't have 300A of 3 phase 480v power at my house - I sitll have a 60 year old fuse box:frown:
I now am hearing that even though it can be added later, it will cost 2 - 3 times more than if it was added during original build - that might change in the future as more people opt for the upgrade, but for now it's somewhat of a custom job.
The 40A 14-50 is certainly adequate for my day to day use, but having the extra capacity on road trips could be beneficial. Most likely there will be more high-power chargers (in addition to the super chargers) on the highways in the coming years. However, if enough super chargers are installed in the right locations, then I will have made the correct choice - time will tell.
Another possibility exists that some type of "home" semi-super charger might become available that would bypass the car's internal chargers using the same method as the large scale versions on the roadways... Unfortunately, I don't have 300A of 3 phase 480v power at my house - I sitll have a 60 year old fuse box:frown:
lolachampcar
Well-Known Member
ordered the second charger but not the HPWC... This gives me options moving forward for the least up front.
I have the second charger because I got a Sig, but would have taken the option anyway. Around here there are a significant number of 70A chargers in the wild that I can use for road trips (and already have!).
I have not purchased the HPWC and know that I don't need it for home use as 40A is quite sufficient (from my experience with the Roadster). That said I did convert my Roadster HPC to J1772 so I can occasionally charge at high current if needed.
I have not purchased the HPWC and know that I don't need it for home use as 40A is quite sufficient (from my experience with the Roadster). That said I did convert my Roadster HPC to J1772 so I can occasionally charge at high current if needed.
There's an S owner out there who built himself a dual 14-50 EVSE so he could charge at 80amps at RV parks. If something like that became generally available it adds another reason to spec your S with twin chargers, as it would make road trips a lot more tolerable while we wait for the Supercharger network to get built out.
lolachampcar
Well-Known Member
Do check the thread on the dual RV thing. There are some serious safety issues associated with doing that.
dhrivnak
Active Member
I have yet to find a public charging station above 6.6 kw. Your area may be different but in 21 months and over 15,000 miles i have yet to find a situation where i could have used the second charger. That infrastructure is not in Tennessee or NC.
mitch672
Active Member
I ordered the twin chargers, because I want to have the fast recharge option, which will not be used daily, but I want the capability. I did not buy the HPWC because I built my own 75A OpenEVSE for 1/2 the cost of the HPWC, plus I can adjust the pilot signal on the OpenEVSE easily (yes, I know you can turn it down via the touchscreen as well). I had a 125A subpanel installed in the garage, a 100A breaker is now feeding my OpenEVSE... BTW, it has been tested with a Tesla Model S with dual chargers (thanks Cinergi for bringing over the Model S to test with)
P.S. OpenEVSE just recently got delayed charging by time of day, both start and stop, so is actually better than the HPWC right now, and the Model S doesn't have delayed/timed charging - yet
75A OpenEVSE: http://code.google.com/p/open-evse/wiki/75AOpenEVSE
P.S. OpenEVSE just recently got delayed charging by time of day, both start and stop, so is actually better than the HPWC right now, and the Model S doesn't have delayed/timed charging - yet
75A OpenEVSE: http://code.google.com/p/open-evse/wiki/75AOpenEVSE
Same here. Figured it was one of those thing better to have and not need, than the other way around. Not many level 3 chargers around here, but got the dual chargers in hopes that the infrastructure will catch up.
lolachampcar
Well-Known Member
mitch672
THANK YOU
I am new to the EV world and was curious what all the fuss was on the AC supply side.
The J1772 primer you provided was perfect.
http://code.google.com/p/open-evse/wiki/J1772Basics
I assume-
The supply side in your garage uses a J1772 cable with the Model S J1772 adapter.
You then advertise the available power to the Model S and switch power according to the spec. Nice.
THANK YOU
I am new to the EV world and was curious what all the fuss was on the AC supply side.
The J1772 primer you provided was perfect.
http://code.google.com/p/open-evse/wiki/J1772Basics
I assume-
The supply side in your garage uses a J1772 cable with the Model S J1772 adapter.
You then advertise the available power to the Model S and switch power according to the spec. Nice.
I created a speadsheet for this. Here are my real numbers-
My normal service costs $0.07934 for the the first 800 kWh. From June-September, it's $0.08039 per kWh over 800 kWh, and from October-May it's $0.05193 per kWh over 800. This is the fully loaded cost- it includes generation, transmission, and distribution. It doesn't include the monthly fee for the meter.
To simplify things, I'm going to use the >800 kWh number since I will easily hit that every month. Further, I'm going to calculate a blended cost per kWh- 4 months at 0.08039 and 8 months at 0.05193 works out to be exactly $0.06 per kWh. Under the EV plan, the fully loaded cost is $0.01690 per kWh between 1a-5a (they call this super off-peak). Off-peak and on-peak cost more. I'll get back to this in a minute. So the cost difference per kWh, standard rate vs super-peak is $0.04310, or 72% off (I earlier said 76% - I was using a non-blended cost for that calculation.)
I'm going to get twin chargers regardless if I do the HPWC for reasons earlier stated (road trips, resale, future). So we need to look at marginal cost- that is, the cost of just adding the HPWC and the wiring to support it. The charger is $1,200. I don't yet know what the wiring/electrician costs are. For the sake of conversation, let's go high and say $1k, which gives me a total marginal cost of $2,200 to support fast charging.
$2200 / $0.04310 = 51,044 kWh needed to break-even. So here is where my knowledge starts to fall off. How much power does it take to fully charge the car? There is heat and other loss, but I don't know the efficiency. Does it take 90kWh to fully charge a 85kWh battery? And there is the fact that most of the time I won't be charging the battery from empty. If I assume 5% loss it should take 89.25 kWh to fully charge an 85 kWh battery. Let's also assume that the battery starts at 50% capacity on average. So we need to charge 42.5 kWh, which at a 5% loss takes 44.625 kWh.
51,044 / 44.625 = 1,143 charge cycles to break-even. Owch! If I've done this correctly, then the additional cost for the HPWC to try to optimize my rate by rapid charging between 1a-5a doesn't make sense for me. Assuming 6 cycles/week, that's 3.6 years. I do have the option of using the EV pricing plan and a NEMA 14-50. If I'm usually starting my charge at 50% capacity, then 4 hours of charge gets me ~90% full.
Ok, so after all that analysis recall I said I would get back to the super-off peak pricing that my utility provides. The downside to their plan is that if you charge outside of the super off-peak periods, they charge you MORE than the standard residential rate (in fact it's over double). I went as so far to think about installing two circuits to my garage; one on my regular panel which gets regular rates, and one behind the EV plan meter that gets the special discount, just to be able to charge during the day if I needed to without incurring the penalty.
So after all of this, I'm going to go with a 14-50 on my regular panel and not even bother with the EV pricing plan. Trying to optimize the cost break between 1a-5am just isn't worth the headache and the lack of convenience of being able to charge at any time. At a break-even of 3.6 years, assuming my analysis is sound, it might be worth it for some. Who knows what charging may look like in 3 years, or what other pricing plans the utilities will come out with as they measure the impact of EV's on the grid.
Comments welcome. I won't be offended if my math is wrong
Andrew
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I was wondering the same thing you did. There are very few >50 amp chargers in the wild.
But then I emailed Sun Country Highway. They are installing 70 amp and 90 amp chargers all over Canada. I'm close enough to Canada that I might well use some of them (particularly in the Niagara Falls - Detroit corridor). So that caused me to decide to get the twin chargers.
So I guess my answer is: find out what plans there are for public chargers in your area (or areas you plan to go). If Superchargers are going to blanket your area, forget the twin chargers as the superchargers are better. If Superchargers aren't coming but someone like Sun Country Highway is installing 70 amp and 90 amp chargers, then definitely get the twin chargers. If neither is happening... well, then if you don't plan to keep the car for very many years, don't bother getting the twin chargers. If you do plan to keep the car for 10+ years, you may want to get the twin chargers for future-proofing in case Sun Country or some similar operator moves into your area.
