Model S - HPWC (High Power Wall Connector)

[biffandsully]

Mayhemm, cottonwood & ecarfan -- thanks for your replies. My electrician is checking to see about a 90 vs 100 amp breaker. We have a pool heater that draws high amps, but he says the load will be ok as long as we don't charge the car and run the heat pump at the same time. It seems like with this issue we might have trouble passing inspection, but the electrician says it will meet code.

Cottonwood, thanks especially for your detailed options, I'm going to cut and paste this and email it to the electrician. He says he's done a lot of research already on this and has installed a couple of Tesla chargers, but I'm not sure if they were HPWCs or NEMA.

 

[Larry Chanin]

I have an HPWC set up for 80A charging, use it every night and am very happy with it. It was an easy decision for me because the HPWC is installed just three feet from my 200A panel. My electrician did have to install a 100A sub panel because my main panel was pretty full and because I also wanted a 50A / 240V plug installed (for my next EV .

Can you give us an idea of how much this cost you?

Thanks.

Larry

 

[ecarfan]

I think it was about $1500.

 

[biffandsully]

Remember that the HPWC can be set to lower circuit breaker settings, and you don't have to pull the largest wire. Check with your electrician and verify local code, but here are the choices that should meet code, and I would have your electrician price out. These are a lot of choices, but if he has the distances, etc figured out, it should not take much time to give you some comparisons.

1. HPWC, 100 Amp Circuit Breaker, #3 wire, 80 Amp charging. You will probably spend an hour or two more for the electrician if he uses #2 wire in addition to the cost of the wire. #2 is a real pain to route inside the HPWC.
2. HPWC, 90 Amp Circuit Breaker, #4 wire, 72 Amp Charging.
3. HPWC, 60 Amp Circuit Breaker, #6 wire, 48 Amp Charging. With the right insulation and inspector, you might even be able to push this to 56 Amp Charging on a 70 Amp CB.
4. 14-50, 50 Amp Circuit Breaker, #6 wire, 40 Amp charging.
5. 14-30, 30 Amp Circuit Breaker, #8 wire, 24 Amp Charging.

The last two choices, 14-50 and 14-30, have the wire size bigger than you need, but at this point, with your long run and the relatively small wire, you probably want a little extra buffer against the 25% current reduction trigger in the MS.

With the prices in hand, you can decide how important that last bit of home charging speed is to you. Home charging is usually overnight, so very high speed charging is not a big issue. Personally, I would probably put in the HPWC with #4 wire and 72 Amp charging, then normally charge at 50 Amps unless I needed the speed.

Good Luck!

My electrician has proposed using #2 SER cable for either a 90 or 100 amp breaker (he was going to check with the manufacturer because he said there are 2 different specs). From above posts 100 is needed for 80 amp charging (if my load can support it) Is this 2 SER cable correct/necessary? If #3 wire is hard to route inside the HPWC, will #2 even fit? Would the cost be less with #3 wire? Sounds like it should be for #4. Also, how would I know if a subpanel is needed?

To state the obvious, know very little about electricity.

 

[pgiralt]

My electrician has proposed using #2 SER cable for either a 90 or 100 amp breaker (he was going to check with the manufacturer because he said there are 2 different specs). From above posts 100 is needed for 80 amp charging (if my load can support it) Is this 2 SER cable correct/necessary? If #3 wire is hard to route inside the HPWC, will #2 even fit? Would the cost be less with #3 wire? Sounds like it should be for #4. Also, how would I know if a subpanel is needed?

To state the obvious, know very little about electricity.

I think your electrician will have a really hard time getting #2 into there. I found #3 was hard enough to work with. I'd go with #3 copper over SER.

Your electrician should know whether a subpanel is required or not. Lots of variables here depending on how things are wired in your house.

 

[biffandsully]

He said he's using #2 copper SE cable. This will be hard to fit?

 

[jerry33]

He said he's using #2 copper SE cable. This will be hard to fit?

I think I recall a post where using #2 was similar to wrestling with a 50 foot anaconda.

 

[Cottonwood]

I think I recall a post where using #2 was similar to wrestling with a 50 foot anaconda.

I think that was me. #2 can be put into an HPWC, it's just a pain... OTOH, sometimes #2 is more common, and sometimes easier to get, than #3. The connectors inside the HPWC are sized for up to a #2. If it were a straight shot into the connector, it would be a tight fit. The way Tesla has designed the HPWC, the big 240 Volt cable has to be bent 90˚ in a very tight space before going into the lug. That 90˚ bend tends to splay the wires in the cable making insertion into the lug a challenge. Comparing installing the #2 wire to wrestling an anaconda may be an exaggeration, but it certainly is a difficult task.

An experienced electrician is probably up to the task of using #2, but they won't enjoy it.

 

[hiroshiy]

Just installed! 200V 80A with 100A breaker (hidden in the locked box).

Waiting for Model S to charge...

 

[Chipper]

Looks real pretty, Hiroshiy. Someone did really nice work!

 

[hiroshiy]

Thanks, @Chipper! Yes my electrician seems to be *very* professional I'm a bit embarrassed to see the old, traditional analog electricity meter though.

 

[Chipper]

Thanks, @Chipper! Yes my electrician seems to be *very* professional I'm a bit embarrassed to see the old, traditional analog electricity meter though.

I also have an old time analog meter at my house. They had to put one of them in when I added the solar to the roof of my house. They tried to put a new meter in, but it would not run backwards as it was supposed to do.

 

[Bugeater]

I also have an old time analog meter at my house. They had to put one of them in when I added the solar to the roof of my house. They tried to put a new meter in, but it would not run backwards as it was supposed to do.

I had gotten a Smart Meter and the installed solar. When the solar was hooked up they removed the smart meter and replaced it with a net meter. A year later they finally upgraded to a Smart Net Meter. They 'is' PG&E...

 

[Lloyd]

I have two meters with PGE. A home meter which is NET SMART, and and Ag meter which is NET only. Seems like a waste as they still have to send someone out to read the ag meter every month, but the house meter reports via the smart function. They are stacked on the same panel.

 

[miimura]

Just installed! 200V 80A with 100A breaker (hidden in the locked box).

Waiting for Model S to charge...

I wonder how much a 20kW boost transformer would cost. The setup above only delivers 16kW to the car. Boosting the voltage to 250V would deliver the full 20kW to the car. Of course, you would have to bump up the breaker to 125A and make sure the upstream wiring can support it.

 

[Cottonwood]

I wonder how much a 20kW boost transformer would cost. The setup above only delivers 16kW to the car. Boosting the voltage to 250V would deliver the full 20kW to the car. Of course, you would have to bump up the breaker to 125A and make sure the upstream wiring can support it.

A pair of these, "416-1261-000 | 1.5kVA Buck-Boost Transformer: single-phase, 240x120 VAC to 32x16 VAC", will has enough VA to convert 208 Volts to 236 Volts and would cost $328 plus shipping plus installation. I figure the total cost would be $600 to $1,000 to do the install. Many ways to do the wiring...

I looked into this for 208 Volt connections in the U.S. and Canada to get the that last bit of power, but it seems a lot to pay for those last few kW of charging, 13.3% faster charging.

 

[FlasherZ]

A pair of these, "416-1261-000 | 1.5kVA Buck-Boost Transformer: single-phase, 240x120 VAC to 32x16 VAC", will has enough VA to convert 208 Volts to 236 Volts and would cost $328 plus shipping plus installation. I figure the total cost would be $600 to $1,000 to do the install. Many ways to do the wiring...

Wrong link? Those are 1.5 kVA each. You'd need about 14 of them for 20 kW, and that's at PF 1.0. You'd probably need a couple more to handle reactance.

(Not to mention the massive code violation implications of installing 14 transformers in parallel and challenges in protecting them all with OCPD's. )

 

[Cottonwood]

Wrong link? Those are 1.5 kVA each. You'd need about 14 of them for 20 kW, and that's at PF 1.0. You'd probably need a couple more to handle reactance.

(Not to mention the massive code violation implications of installing 14 transformers in parallel and challenges in protecting them all with OCPD's. )

Actually, it would be wired as a boost transformer, see Buck-Boost Transformers Overview and Buck-boost transformer - Wikipedia, only carrying a fraction of the total power delivered. Because the Boost Transformers are only carrying the "extra" power, all you need is 2x1.5 kVA to get 3.0 kVA, the real advantage of the buck-boost architecture. Buck-boost transformer - Wikipedia

To use these two, you could use 2x of Wiring Diagram 4, or use Wiring Diagram 3 with the second transformer wired in a "mirror" configuration for symmetric boost on either side of the LV input.

Because the Tesla AC chargers are meant to be friendly to the grid and meet some European specs, I believe that they have a power factor that is better than 0.95 making them essentially a resistive load. This means that kVA and kW are very close to equal. This is very important in Supercharger installations.

If this were to be done in any volume, it would be better to use a single, larger, boost transformer, but I thought this pair was a reasonable example for approximate costing.

Even with only 2, 1.5 kVA or 1, 3 kVA boost transformer, this solution for 13.3% extra charge rate is complicated, costly, and probably not worth the effort.

 

[miimura]

A pair of these, "416-1261-000 | 1.5kVA Buck-Boost Transformer: single-phase, 240x120 VAC to 32x16 VAC", will has enough VA to convert 208 Volts to 236 Volts and would cost $328 plus shipping plus installation. I figure the total cost would be $600 to $1,000 to do the install. Many ways to do the wiring...

I looked into this for 208 Volt connections in the U.S. and Canada to get the that last bit of power, but it seems a lot to pay for those last few kW of charging, 13.3% faster charging.

I know this is NOT an easy or cost effective thing to do. However, in the Japan situation, there is a full 25% increase to be had.

 

[PhilBa]

I would step back from this issue and ask yourself if you really need to squeeze that last little bit of charging performance out of your system. On average, how far do you drive and what is your minimum needed charge time? At best, it will save you a bit more than an hour for a zero to full charge (67 minutes - 4:27 vs 5:34). Since you probably won't drive your battery to empty, the actual time difference will be quite a bit less.