Single vs Twin Charger

Single vs Twin Charger

I'm about to place my order. Trying to decide on single vs twin charger without getting the HPWC. Will there be any opportunity to use the twin charger with the J1772 chargers in the wild. Most j1772 do not have 80 amp to take advantage of the twin charger for fast charging up to 62 miles/hour. Any thoughts?

nickjhowe | 28 gennaio 2013

I think you have it right - if you can find a high amp J1772 you'll be able to take advantage. If not, its a waste of money. I decided not to.

stephen.kamichik | 28 gennaio 2013


jat | 28 gennaio 2013

There are 70A chargers across Canada, and over time there may be more. You won't need them for Superchargers or other fast-DC-charging (CHAdeMO and SAE if they ever install enough and Tesla makes an adapter).

One thing to think about which might change your mind about the HPWC - if you get home from work and want to head out on an out-of-town trip, you want to be able to replace the charge used in your commute quickly. In my case, I had to wait 3 hours before I could leave on a trip charging off a 14-50 plug (fortunately, I had other things I needed to get done before heading out, so that was fine; if not, I could have charged near work to shorten the time).

Basically, you are deciding between wasting $1500 now if you get it but don't use it, and wasting $2100 (less cost-of-money differences) if you don't get it and later decide you do want it (it is $3600 to install after-the-fact). Once you assign those subjective probabilities, it is an easy question to answer.

petero | 28 gennaio 2013

I agree with nick. I didn't order it for my 60kWh MS. I put in a 220 amp plug as this easily recharges my battery overnight.

However, you never know what the future holds 'in the wild.'

mcptwo | 28 gennaio 2013

I had this discussion with my Tesla rep. I asked for twin chargers and was discouraged because the Supercharger network will predominate. Aside from the HPWC at home the Tesla service facilities and some of the Tesla stores have charging in the 70A range. That is why I thought twin chargers would be useful, but it appears that Tesla does not want to encourage charging at the service facilities. Also it looks like Sun Country in Canada with their CS-90 chargers delivers 70-90A, and again twin chargers would be better in that case.
I also noticed that if you order twin chargers with your Model S, the cost is $1,500.00 vs. $3,500.00 if they are installed later.

stevenmaifert | 28 gennaio 2013

Unless you drive the battery to exhaustion everyday, and need to recharge faster than an overnight with the UMC, you don't need the twin chargers and the HPWC.

High power L2 J1772 units are rare. Remember, they are sized for the Leafs and the Volts, not Model S. Most charge by the hour, not by how many trons you can suck out of them in a charging session, so the owners make out. There is no economic incentive for the owners of commercial chargers like Blink or ChargePoint to give us anything more than 30amps. I'm a Blink Plus member and would love to pull 70amps from their chargers and still only pay $1/hr... not gonna happen anytime soon.

EVTripPlanner | 28 gennaio 2013

I agree with most above - no reason for twin charger. Home outlet is 240V x 40A max, which is under 10 kW. Supercharger is DC, so inverter/rectifier (charger) is irrelevant. I put together a reference sheet on charging/wattage/rates, etc at - it provides all the details and lets you do some energy/cost analysis.

hfcolvin | 28 gennaio 2013

I went single charger. I think future of high efficiency charging is in DC (direct current, not District of Columbia). Hopefully, we'll see a fairly extensive network of Superchargers over the next 1-2 years, but I don't see a lot of effort being put into 60-70A AC charger networks.

DouglasR | 28 gennaio 2013

I configured with a single charger and did not get the HPWC. Soon I will be upgrading to the twin chargers for $3600. Last month, I had wanted to drive from Seattle to the Bay Area, but cancelled the trip because it would have taken me more than three days with a single charger. With twin chargers, I can take advantage of the "Tesla Highway" -- a network of 70 amp Roadster HPCs stretching from Vancouver BC to southern California. See That would have permitted me to make the trip in two days. There is also a network of 70 amp J1772 ESVEs across southern Canada, if I want to drive east. See It would have been a lot cheaper and easier had I configured with twin chargers in the first place.

markapeterman | 28 gennaio 2013

DouglasR - just curious, but how are you going to feel if they open superchargers from Seattle to SF right after your second charger is installed? I would expect this within the next 6-9 months based on their stated goals for 2013.

Brian H | 28 gennaio 2013

There's also Peter7's trick ( with his Multi-Input EVSE, which draws from 2 14-50s at once (e.g., at RV camps). Such devices may become available in the future.

edavis008 | 28 gennaio 2013

How can I get my hands on one of those Multi-Input EVSE's?

DouglasR | 28 gennaio 2013


The sooner they do that, the better. The supercharger network will be much faster, cheaper, and easier to use than the 70-80 amp power sources. The supercharger network has two problems, however. First, it is not available now in most places, and I do not have confidence that TM will meet its proposed installation schedule. Second, there are many places where the supercharger network will NEVER be (or you might have to drive 50 miles out of the way to add 150 miles).

For me, it is all about flexibility. I hope to get that twin charger installed next week, and I'm thinking again about that trip to California. If TM offered a CHAdeMO adapter, I'd buy that too. I understand that everyone must make his or her own cost-benefit analysis. Not everyone will want to spring for the upgrade after the car is delivered; it's an easier choice to order the upgrade with the car.

I sometimes regret it when I want something but fail to buy it. I almost never regret it when I buy something I want.

I am 3146 | 28 gennaio 2013

I went with double chargers and HPWC. My thought process was that after aday at the office, drive home, plug in, get showered, dressed to go out for dinner, have an extra 62 miles or so of charge. Enough to get me to Atlantic City. Couldn't do that with a single charger.

Brian H | 28 gennaio 2013

I am;
Your handle sounds very Borg; "I am 7 of 9". ;)

laalan | 1 febbraio 2013

Just for clarity, if I put in a 40 amp breaker, am I getting the maximum benefit from the single charger (80% is 32Amp) or is the maximum benefit 50 amp breaker (80% is 40AMP useable) without the twin charger? Or is it 60 AMP breaker drawing 50 amps the maximum benefit?

laalan | 1 febbraio 2013

Answers my own question. 50 AMP breaker pulls the maximum 40 amp continuous to get 31 miles per hour of charge.

Hills | 1 febbraio 2013

31 miles/hr is ideal miles (55 mph on cruise control, flat highway, good weather), and is not the definition displayed on the pre-programed on Model S speedometer. I get actual 22-24 miles/hr displayed on the speedometer (rated miles). However, I suspect the actual charge rate is higher than the display, but have not verified scientifically. Agree with the 40 amp draw on 50 amp breaker.

nickjhowe | 1 febbraio 2013

Charging rate varies with how full the battery is. You WILL get 31 if you are not just topping off the battery.

DouglasR | 1 febbraio 2013


I've never seen 31 rated miles, even when I start with a fairly empty "tank." However, I think if I set the units to ideal instead of rated miles, I would have hit 31.

Shelmire | 2 febbraio 2013

Guys, I've read all of your comments, but the word "never" is a big one when claiming you will never need your twin charger.

Look, I also have a Yukon with four wheel drive. I "never" need to use it, but once a year (snow, stuck in a muddy field parking lot at my kids ballgame) when I DO need it I've got it, plain and simple.

Plan for real life. If I need a quick charge cause there is an emergency, a whim, then I am not sitting around my house learning to knit when I could be traveling.

If you 'never" leave your town (never, never, never), now that's when you shouldn't need it.

You're welcome.