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Moderate Power Tesla DC Charger Product Proposal

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Cottonwood

Cottonwood

Roadster#433, Model S#S37
Feb 27, 2009
5,089
184
Colorado
#1
A nice product for Tesla to produce and sell (maybe at a reasonable price...) would be a Moderate-Power, Tesla-connector DC charger. This would be a great product for high power home charging and a high end Destination Charger. Just like Superchargers, Destination Chargers, and reasonable priced HPWC's, it would be in Tesla's interest to sell this at a reasonable price.

See Update: Model X has a single charger, but only 48A capable for concerns that some Model X buyers have about being limited to 48 Amp charging, as well as the general need for a medium power charger between Superchargers.


Here is a proposal for a strawman design:

  1. Use 3 of the 48 Amp charging modules. This would allow up to 36 kW from the charger.
  2. Allow use of single and 3-phase connections, including 3-phase 277/480 Volts for commercial setups.
  3. Have several power levels to support various circuit/wire sizes. For example, in the 240V, single phase mode, allow power levels for 200, 175, 150, 125, 100, 90, and 80 Amp breakers. Allow similar 3-phase breaker choices.
  4. A reasonable size unit with wall mount and outdoor options.
 
#3
I think this is probably the equivalent of the mini-supercharger that they will sell to commercial companies. Not sure how many would jump on it given difficulties with installation (beyond 150A, it's a whole new game). Great option to have, but I suspect there'd be fewer than 100 who would consider it until they start looking at fleet cars (Model 3?).
 
#5
Matias said:
What is the benefit of this compared to chademo? Ok, you would not need adapter, but on the other hand, many brands are chademo compatible. With chademo you can serve more cars.
Click to expand...

Hopefully price. Other than units that are almost "do it yourself," most CHAdeMO units are in the $35k to $50k region. Tesla should be able to build and sell this for under $5k. Tesla does not need to make much money on this because it helps sell more Teslas.

In addition, the CHAdeMO connector and the CHAdeMO adapter are very big and awkward to use.
 
#6
FlasherZ said:
I think this is probably the equivalent of the mini-supercharger that they will sell to commercial companies. Not sure how many would jump on it given difficulties with installation (beyond 150A, it's a whole new game). Great option to have, but I suspect there'd be fewer than 100 who would consider it until they start looking at fleet cars (Model 3?).
Click to expand...

You are a lot more knowledgeable than me on the subject.. but lets just say we run it from a household split-phase (US/CAN) panel at 150A. 36kW of power on the input side of the DC Charger. Now, using 92% efficiency, we get 33.1kW of power delivered to the battery. Disregarding IR of the cells during charging, let's just calculate 33kW getting in the battery pack without any losses.

Quick calculation : around 77-78kWh usable in my 85kWh pack. When Supercharging, I taper off to 33kW at around 90-91%SOC. That's 70kWh delivered. Assuming that we can push enough current to get to get the full 33kW at low SOC voltage... that's 2.1hours at 33kW.

Would that qualify as a non-continuous load (based on 3h load correct?). We're definitely on the edge of the law here but I was wondering if it was possible.

Finding a sub-panel rated for 150A without any main breaker is a bit harder, especially if you like them small, but that could be done.
 
#7
I'd probably be a customer at our lodge. We've not yet put in an HPWC for our customers, and I'd certainly be willing to hold off awaiting to see if your suggestion has legs.
 
#10
I've mentioned this off-the-cuff in a few other threads, because I don't know for sure how and if it'd work. For those who know more about this kind of thing than I do - how difficult would it be for a Powerwall to include DC charging ability? It seems to me that if this were possible, it would provide a number of benefits. First, you're not restricted by the power supplied to the Powerwall. Because it can already hold a charge, you can be in the process of transferring to the car while also recharging the Powerwall. I recognize this is somewhat lossy.. but for speed purposes it would be quicker.

Also, while the "charger" (Powerwall) is not in use for the car, it provides other benefits to the home. For those who complained about the 4-hour low rate charging window, this gives an opportunity to time shift your use into that window. And finally, it provides a huge incentive to Tesla owners who are on the fence about Powerwall. It seems to work as a great add-on product.

Of course, this is all dependent upon it being possible at a reasonable cost.
 
#11
Cottonwood said:
Hopefully price. Other than units that are almost "do it yourself," most CHAdeMO units are in the $35k to $50k region. Tesla should be able to build and sell this for under $5k..
Click to expand...

The charger linked in the other discussion, that does 25 to 35 kW, comes out to less than $5k. And as others already mentioned, CHADeMO can be used by many more EVs (many of which need to charge more urgent than a Model S).
 
#12
David99 said:
The charger linked in the other discussion, that does 25 to 35 kW, comes out to less than $5k. And as others already mentioned, CHADeMO can be used by many more EVs (many of which need to charge more urgent than a Model S).
Click to expand...

That other charger is a do-it-yourself, erector set kind of contraption. What I proposed is a bolt it on the wall, connect the wires, reliable box. On top of that, that unit will not go up to the Voltages needed for an 85/90 kWh Tesla. At Electric Motor Werks, Inc. - QuickCharge-25000 HV - a 25kW PFC charger for HIGHER voltage batteries, it states: "There is only one limitation – you can only charge battery packs with end-of-charge voltage above the peak of the rectified AC wave (~340V from the 240VAC supply)" You need over 400 Volts DC for an 85/90 kWh Tesla.

In addition, as I said earlier, the CHAdeMO connector and the CHAdeMO adapter are very big and awkward to use.
 
Last edited:
#13
ohmman said:
how difficult would it be for a Powerwall to include DC charging ability?
Click to expand...

The Powerwall's output power is limited. You would need two of them to get the equivalent of a single charger. You'd need 4 to match a dual charger. To get close to a CHADeMO you'd need 10. But that's just theory. The Voltage of the Powerwall isn't high enough to charge the Model S. So you would need a DC-DC converter and an active charger in between. Pretty pricey. Even with 10 powerwalls, you would need their entire capacity to charge your Model S. So then what. You would have to wait several days before your Solar panels have recharged your Powerwalls. 10 Powerwalls alone are $35k.

- - - Updated - - -

Cottonwood said:
In addition, as I said earlier, the CHAdeMO connector and the CHAdeMO adapter are very big and awkward to use.
Click to expand...

True, that thing is a pain. I feel embarrassed when I have to use mine in the public LOL
 
#14
David99 said:
The Powerwall's output power is limited. You would need two of them to get the equivalent of a single charger. You'd need 4 to match a dual charger. To get close to a CHADeMO you'd need 10. But that's just theory. The Voltage of the Powerwall isn't high enough to charge the Model S. So you would need a DC-DC converter and an active charger in between. Pretty pricey. Even with 10 powerwalls, you would need their entire capacity to charge your Model S. So then what. You would have to wait several days before your Solar panels have recharged your Powerwalls. 10 Powerwalls alone are $35k.
Click to expand...

Thanks. I was talking about DC-to-DC, and I didn't intend to charge the entire MS from empty solely off of the Powerwall. Powerwalls don't consume DC direct from solar, right? They have an inverter built in somewhere to take grid power (for those without solar) and store it? If so, the rate of charge to the MS would be limited only by the consumption rate of the Powerwall, since that would be the actual "charger" for the car (again, assuming it was delivering DC).
 
#16
llavalle said:
Would that qualify as a non-continuous load (based on 3h load correct?). We're definitely on the edge of the law here but I was wondering if it was possible.

Finding a sub-panel rated for 150A without any main breaker is a bit harder, especially if you like them small, but that could be done.
Click to expand...

All EV charging loads are considered continuous loads, without regard to any timing (art 625).

It's easy to find a sub-panel @ 150A with main lugs only - they're frequently used where external disconnects are required (e.g., CA).

- - - Updated - - -

Cottonwood said:
That other charger is a do-it-yourself, erector set kind of contraption. What I proposed is a bolt it on the wall, connect the wires, reliable box. On top of that, that unit will not go up to the Voltages needed for an 85/90 kWh Tesla. At Electric Motor Werks, Inc. - QuickCharge-25000 HV - a 25kW PFC charger for HIGHER voltage batteries, it states: "There is only one limitation – you can only charge battery packs with end-of-charge voltage above the peak of the rectified AC wave (~340V from the 240VAC supply)" You need over 400 Volts DC for an 85/90 kWh Tesla.

In addition, as I said earlier, the CHAdeMO connector and the CHAdeMO adapter are very big and awkward to use.
Click to expand...

I noted this in the other thread, too, but the voltage is just fine. They're saying the finishing voltage must be above 340VAC, not below - it'll work fine for a Tesla battery.
 
#17
FlasherZ said:
I noted this in the other thread, too, but the voltage is just fine. They're saying the finishing voltage must be above 340VAC, not below - it'll work fine for a Tesla battery.
Click to expand...

Thanks for the correction. As I said in the other thread, the 350 Volt final Voltage of 60/70's is pretty close to their 340 threshold.

Has anyone tried to use one of these EMW CHAdeMO setups?
 
#18
I don't think this makes much sense when you can get dual charges and 20kw for a much more reasonable price. Perhaps something like a 40-50kw charger for businesses since that would be a noticeable step up over 20kw. But home panels probably won't work very well with more than 20kw.

The other thing that might be cool is a straight solar charger. So you connect up the panels ontop of your garage (or parking spot at work), hook them into the charging box, then plug that into your car.
 
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