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Wishing Out Loud: A mini Tesla DC charger

mociaf9

Active Member
Oct 18, 2018
3,197
6,671
CA
Would it be possible to take two AC EVSEs and combine their output into one DC stream of up to 23 kW ?
No because AC EVSE don't convert to DC electricity at all, their output is AC. The car's on-board charger does all the converting (rectifying) of AC to DC. It's possible to build or buy a low powered DC charger--for example, lots of Harley-Davidson dealers have a 25 kW CCS DC charging station--but you're never going to get there by adding up AC EVSEs. A quick search online shows such 25 kW DCFC stations to run you in the range of $10k-$15k.
 

SageBrush

REJECT Fascism
May 7, 2015
13,240
17,984
New Mexico
No because AC EVSE don't convert to DC electricity at all, their output is AC. The car's on-board charger does all the converting (rectifying) of AC to DC. It's possible to build or buy a low powered DC charger--for example, lots of Harley-Davidson dealers have a 25 kW CCS DC charging station--but you're never going to get there by adding up AC EVSEs. A quick search online shows such 25 kW DCFC stations to run you in the range of $10k-$15k.
You are right, I should have been thinking of two 48 Amp OBC (on-board chargers)
 

LoudMusic

Active Member
Jul 21, 2020
1,412
1,641
Arkansas
What would be the market for this charger?

I'd like to see 50 to 100 kw chargers at interstate restaurants like Cracker-barrel. Tesla Urban Superchargers are an excellent example.

You don't need 250kw because it'll be done before you are and you'd have to move the car, but you need a lot more than 11kw. 45 minutes of dining on a 72kw Supercharger would be pretty perfect for a road trip.
 

SageBrush

REJECT Fascism
May 7, 2015
13,240
17,984
New Mexico
What would be the market for this charger?
Any and every place you e.g. want to spend 1 - 2 hours and gain 100 to 200 miles of range.

My state of NM is the 5th largest in the USA and is serviced by 11 Superchargers. They do a pretty good job of covering the interstates, but destinations reached by rural roadways become a matter of AC charging at ~ 30 miles an hour. It would be a boon if small towns could service EV travelers and tourists with an investment of $10 - $20K. A good example of this is @nwdiver 's project to bring charging to SE New Mexico, and specifically to the Carlsbad Caverns national park. He is shooting for L2 charging, but slow L3 would be so much more valuable and attractive to EV drivers in these otherwise underserved areas.

To wit:
  • National and State Parks
  • Non-Coastal America, outside of the megapolis's
  • Towns of ~ 50k population or less
  • 50+ miles from an interstate
 
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nwdiver

Well-Known Member
Feb 17, 2013
8,854
12,935
United States
Especially with all these cars with large 100kWh batteries and 48A chargers. There are some CCS options in the ~25kW range but they cost ~$10k. I bet Tesla could do a 30kW L3 charger for $5k. I'd be all over that. Have the ability to split it between two pedestals. So even if you're sharing you'd be charging faster than 48A L2.
 
What was the size of the dual chargers in the old model S? Didn't these cars charge at 100 amp?

I suspect that one reason ~20kW charging isn't practical is that it usually requires a service upgrade in both residential and smaller commercial settings. While some of us should not have added a 60amp serice at home, in practice its fine for almost all 200 amp services.

I think what is lacking in charging will be large numbers of level 2 chargers at work, for overnight street parking, and in apartment parking lots.
 
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I'd like to see 50 to 100 kw chargers at interstate restaurants like Cracker-barrel. Tesla Urban Superchargers are an excellent example.

You don't need 250kw because it'll be done before you are and you'd have to move the car, but you need a lot more than 11kw. 45 minutes of dining on a 72kw Supercharger would be pretty perfect for a road trip.
Hopefully higher power chargers can turn into a profit center for some restaurants in some locations.
 

SageBrush

REJECT Fascism
May 7, 2015
13,240
17,984
New Mexico
I suspect that one reason ~20kW charging isn't practical is that it usually requires a service upgrade
I don't know what is usual, or the range of costs if an upgrade is needed.
Referring again to nwdiver's projects in SE New Mexico, he is installing a 230 Amp line at one of the McD properties he has gained permission to install charging. I presume that is 240v so it is 55 kW, but if it is a 120v feed that is still 27 kW.

His other project included an upgrade that was installed for under $4k
 

ItsNotAboutTheMoney

Well-Known Member
Jul 12, 2012
11,623
9,711
Maine
Especially with all these cars with large 100kWh batteries and 48A chargers. There are some CCS options in the ~25kW range but they cost ~$10k. I bet Tesla could do a 30kW L3 charger for $5k. I'd be all over that. Have the ability to split it between two pedestals. So even if you're sharing you'd be charging faster than 48A L2.

The fundamental problem is that 25kW is too slow for on-the-road charging, and overkill for most peoples' home charging. When EVs are cheaper and there are more electricity guzzlers that benefit from higher power, then maybe there'll be more of a market for 22kW charging.
 
I don't know what is usual, or the range of costs if an upgrade is needed.
Referring again to nwdiver's projects in SE New Mexico, he is installing a 230 Amp line at one of the McD properties he has gained permission to install charging. I presume that is 240v so it is 55 kW, but if it is a 120v feed that is still 27 kW.

His other project included an upgrade that was installed for under $4k
It could even be 208v three phase. He will need to tell us.

So, refreshing my on-board charger my knowledge,
- Pre 2016 MS could have a 22kw charger (dual I think)
- Current S/X is 16.5kw (100 amp circuit)
- Current 3/Y is 11 kw (60 amp circuit)

Installing low power DC charging may be kinda pricey for the functionality.
 
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SageBrush

REJECT Fascism
May 7, 2015
13,240
17,984
New Mexico
- Current S/X is 16.5kw (100 amp circuit)
- Current 3/Y is 11 kw (60 amp circuit)

I don't think that is quite right. These days Tesla uses 16 Amp sub-components.
In N. America with single phase, cars are either 32 or 48 Amps at 240v
In Europe with 3 phase, cars are 32*sqrt(3)*0.208 = 11.5 kW

My suggestion amounts to building a product that holds 6, 16Amp subcomponents. In Tesla units, that would be two fully outfitted OBC circuit boards.
 
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nwdiver

Well-Known Member
Feb 17, 2013
8,854
12,935
United States
It could even be 208v three phase. He will need to tell us.

So, refreshing my on-board charger my knowledge,
- Pre 2016 MS could have a 22kw charger (dual I think)
- Current S/X is 16.5kw (100 amp circuit)
- Current 3/Y is 11 kw (60 amp circuit)

Installing low power DC charging may be kinda pricey for the functionality.

The install we're working on now is just a 240v 320A service drop. The older cars could charge at 80A. They're current limited not power limited which would be the other benefit to L3. At most commercial sites even a 80A car would only get (208v)(80A) = 16.6kW. So using a low power L3 charger could almost double the speed.

I would be too slow to replace a supercharger but I think there's niche between 11.4kW and 70kW. It could help bridge some of the ~250 mile gaps. Places that people often find themselves not quite being able to make their destination or the next supercharger. Or this could free you from the tyranny of SC locations. Instead of going to a SC go have dinner where you want for an hour and pick up ~120 miles of range...

30kW of grid-tied solar PV inverter costs ~$5k. 30kW of EV charger should cost less. If Tesla took advantage of the existing supply chain and packaged 3 48A chargers I can't image the unit cost would be >$3k. Maybe retail it for ~$5k. I was looking at some of the quotes for L2 public chargers. They average around $20k. Most of that is labor. So for a ~25% increase in cost you could get a 300% increase in charge speed.
 

SageBrush

REJECT Fascism
May 7, 2015
13,240
17,984
New Mexico
I think there's niche between 11.4kW and 70kW. It could help bridge some of the ~250 mile gaps. Places that people often find themselves not quite being able to make their destination or the next supercharger. Or this could free you from the tyranny of SC locations. Instead of going to a SC go have dinner where you want for an hour and pick up ~120 miles of range...

30kW of grid-tied solar PV inverter costs ~$5k. 30kW of EV charger should cost less. If Tesla took advantage of the existing supply chain and packaged 3 48A chargers I can't image the unit cost would be >$3k. Maybe retail it for ~$5k. I was looking at some of the quotes for L2 public chargers. They average around $20k. Most of that is labor. So for a ~25% increase in cost you could get a 300% increase in charge speed.

Exactly. There is also a definite slot for installations that do not push billing into tariff schedules with demand charges
 
They already have the 72 kw Urban Supercharger, and 11.5 kW wall charger, so you really are looking for a Goldilocks. I do like your idea for having them at State Parks or places to eat along major routes but I just dont see that on a high priority list for them right now. They still have a lot of open area to fill in with regular super chargers as more and more people own Tesla vehicles everyday and the CyberTruck and Semi coming down the road.
 
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SageBrush

REJECT Fascism
May 7, 2015
13,240
17,984
New Mexico
They already have the 72 kw Urban Supercharger, and 11.5 kW wall charger, so you really are looking for a Goldilocks.

Yes, although the Urban Supercharger is too expensive to install and run for anybody not named Tesla. A low-ish power DC offer would hopefully be in the price range that a commercial or government entity would want to install. It might mitigate the demand charge conundrum, and even Tesla produces a lot of 32 Amp (~ 8 kW) AC charging cars.

For the consumer, it is the difference between stopping at a location 1 hour instead of two or three; or two hours instead of four or six.
 
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They still have a lot of open area to fill in with regular super chargers as more and more people own Tesla vehicles everyday and the CyberTruck and Semi coming down the road.

It seems to me that Tesla is reaching the point where they will need to address CCS in North America. Tesla doesn't want to fill all the "holes" that are not profitable.
 

moa999

2020 3 SR+ MSM
Mar 4, 2020
1,620
1,400
Sydney, AUS
ABB makes a 25kW DC charger in the Euro market.. but it's closer to US$10k. 3ph 32A is gettable to power it without any fancy transformers and the like.

 
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