Charging Basics: School Me.

[Bloomj]

We have two EVs, a M3 LR and a much cheaper Nissan Leaf for local/commute, and the J1772 with the Tesla-provided adapter serves well for our purpose.

That makes no sense. A Wall CONNECTOR (not charger, the charger is in the car) is hardwired into the circuit. If you have a 6-50 outlet already, just buy the 6-50 adapter for the UMC and you’re done. You’ll charge at 32A. No reason to think about a 14-50 outlet in your circumstances.

I have a detached garage with the existing 50a circuit. Long term I will be parking in the attached garage and will have to add a breaker to the panel, etc. if that becomes reality I prefer to go ahead and install a receptacle so it’s there and then i can choose to “plug in” the wall connector or whatever I may do in the future. I just like doing things that make for future proofing / easier to update/change whatever.

 

[Bloomj]

Why in the world?!?! It doesn't make more sense. The wall connector manual says it is supposed to be a hardwired device. I know some people do that, but it is less reliable and safe by putting more loose junction points in versus hardwired.

I hear you on the safety but realistically the wires are landed on terminals anyway. If it came with a cable molded in place or somehow permanently fixed I’d leave it. Since that doesn’t appear to be the case I’ll throw on a 14-50 plug and do it that way. If done properly it should be just fine.

 

[Bloomj]

I would suggest installing the HPWC as a hard wired device. There are people that add a cord and plug it in, but you are adding a couple of extra points of failure (and fire) that you can avoid by hard wiring it.

My home setup is 4 J1772's at 80A (or less) with proper disconnects and the works. They are home built units based on OpenEVSE hardware, uprated contactors and J1772 cables. It cost me more per station than just buying the Tesla units, but I don't like Vendor lockin. I can also manage these via a web browser or API call. Also I have MORE power available than I could properly distribute via the HPWC management protocol. I am an extreme example of why you go a different direction, but most people don't have 300 amp service to their garage.

That’s pretty cool. I haven’t considered building my own unit. I only need one so it’s probably not worth the effort for me but would be neat. Plus I just completed a 40 panel ground mount solar install so I’m done with big projects for a bit.

 

[Heckler]

If you end up buying a second EV, you can have 2 units and have both cars plugged in at the same time. The units "speak" to each other to manage the load between the two units. This would also work with a non-Tesla by using a Tesla-to-J1772 adapter (TeslaTap also sells converted Tesla HPWC with J1772 plug). Perhaps in the future, Tesla may also sell a J1772 unit as they do have them at some of their public stations (well, at least one in Toronto).

Do we know that 2+ (up to four) Tesla HPWC units will still be able to daisy-chained and do their Master/Slave load sharing if one of them is being used with aTesla-to-J1772 adapter like the TeslaTap that presumably doesn't have either continuity to similar communications protocol from a non-Tesla vehicle?

 

[TT97]

Do we know that 2+ (up to four) Tesla HPWC units will still be able to daisy-chained and do their Master/Slave load sharing if one of them is being used with aTesla-to-J1772 adapter like the TeslaTap that presumably doesn't have either continuity to similar communications protocol from a non-Tesla vehicle?

I had asked the same question last year and got confirmation that it does work (although the person answering was not the person who actually did the setup).

Possible to use Tesla Wall Charger to charge our CMax Energi as well?

Also, if you go to the TeslaTap store, they sell the Tesla HPWC with the J1772 plug conversion and it states, "Power sharing feature allows a single circuit breaker to be connected and shared, servicing up to 4 units at the same time. That's right... up to 4 charge stations on one electrical circuit !!!"

WALL50 Tesla HPWC with J1772 Conversion 24 Foot

 

[FarmerDave]

A big advantage of using the Tesla Wall Connector is that if you have two or more Teslas (you probably will eventually) you can connect two HPWCs to the same circuit. The HPWCs will communicate with each other so that if you have two cars plugged in at the same time they won't exceed the preset load of the circuit.

Example: I have a 50 amp circuit to my garage. My HPWCs are preset to allow a maximum draw of 40 amps per car (the Model X could draw up to 72 amps if permitted). If I charge one car, it will get a 40 amp charge. If I charge two cars at the same time, they each get a 20 amp charge. When one car reaches its set charge limit, the other car starts getting the full 40 amps automatically.

We don't have to think about it, it takes two seconds to plug in, and both cars are always plugged in when they're not being driven.

 

[timk225]

I hear you on the safety but realistically the wires are landed on terminals anyway. If it came with a cable molded in place or somehow permanently fixed I’d leave it. Since that doesn’t appear to be the case I’ll throw on a 14-50 plug and do it that way. If done properly it should be just fine.

If you're going to install a 14-50 outlet, then why even spend hundreds of dollars getting an HPWC? It won't charge much faster, maybe 40 amps instead of 32, at best. Just put in the 14-50 and use the charging adapter that came with the car and a $35 14-50 adapter from Tesla. Almost as good and a whole lot cheaper!

 

[Bloomj]

If you're going to install a 14-50 outlet, then why even spend hundreds of dollars getting an HPWC? It won't charge much faster, maybe 40 amps instead of 32, at best. Just put in the 14-50 and use the charging adapter that came with the car and a $35 14-50 adapter from Tesla. Almost as good and a whole lot cheaper!

I’m headed that direction.

 

[EVDRVN]

Just to add and a little pet peeve the Tesla chargER is IN the car and not on your wall. This is the same for all cars, phones and lit-ion devices. People often mistakenly call the power cable a charger but it's not. So you installed a Tesla Wall Connector (NOT a chargER) which is also a ChargING Station.

When you plug into a DC fast chargER it is bypassing the cars internal chargER. This is why Tesla calls it a Super ChargER and CCS is also a chargER. All level 1 and 2 are ChargING Stations (AC).

L1 and L2 units are not chargers the are EVSE units not power cables. Cell phones and computers, etc have external chargers in that they have the power conversion and partial regulation with "BMS" in the device. Tesla cars for AC charging use the same modules that are in the SC units, which are stacked and fed HV AC. You can take several Tesla onboard charger units and stack them and make a SC.

 

[timk225]

I make it a point to call it a charge ADAPTER. Calling it a charging cable doesn't seem right because it has that box in it. And EVSE is too complicated.

 

[EVDRVN]

I make it a point to call it a charge ADAPTER. Calling it a charging cable doesn't seem right because it has that box in it. And EVSE is too complicated.

Except it does not adapt anything. Chargers do have boxes but it is not a charger. An EVSE is a safety device that provides several critical functions not limited to GFI protection, arc protection via disconnect, general disconnect and pilot signaling for draw compliance. The EVSE has zero charging functions as it does no power conversion or regulation or any BMS function. A power cable would be a better inaccurate description.