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Wishing Out Loud: A mini Tesla DC charger

zecar

Member
Nov 30, 2017
397
260
Chicago
So... my thought is that in the future AC charging (in cars) will be discontinued and the cars will be DC charging only. Why put the AC charger in the vehicle... put the the AC to DC converter in the wall unit. And as such, lower KW DC chargers will become more prevalent. 10, 15, 20KW will be options. For the small town, perhaps 50KW to 100KW units backed by a power wall to even out the load so it can be driven by a lower KW power feed from grid.

Mike

Currently the trend is the opposite. Manufacturers are up-specing to 11kW in car chargers. IIRC even the Bolt now offers a larger charger option.

Tesla can't even shed the 12v legacy system.
 

miimura

Well-Known Member
Aug 21, 2013
6,176
5,774
Los Altos, CA
It would be nice if a DCFC was on the market that could support 208/240V at 160A for full utilization of a single 200A service feeder for 33.2/38.4 kW.
Yes, a 200A 240V service is a nice round number. I happen to have an empty space in my main panel for a second 200A main breaker. However, if you had a 208V service, you should probably load all three phases. In that case 100A 208V 3-phase is 36kW which should be fed with a 125A breaker.

Many residential 240V service panels are also limited to 125A breakers on the main bus. This is perfect for the available 24kW DCFC units on the market.
 

miimura

Well-Known Member
Aug 21, 2013
6,176
5,774
Los Altos, CA
Why would I want to pay for a system to charge a Tesla at 15kW DC? Whats the use case?
The use case for this unit is bi-directional. If you have taken energy out of the car to supplement your house, you probably need to put it back more quickly before you drive again.
 

mociaf9

Active Member
Oct 18, 2018
2,554
5,182
CA
The use case for this unit is bi-directional. If you have taken energy out of the car to supplement your house, you probably need to put it back more quickly before you drive again.
Or anywhere (or anytime) the power grid isn't stable, then in the short time that the electric grid is back up before falling over again.
 
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zecar

Member
Nov 30, 2017
397
260
Chicago
Yes, a 200A 240V service is a nice round number. I happen to have an empty space in my main panel for a second 200A main breaker. However, if you had a 208V service, you should probably load all three phases. In that case 100A 208V 3-phase is 36kW which should be fed with a 125A breaker.

Many residential 240V service panels are also limited to 125A breakers on the main bus. This is perfect for the available 24kW DCFC units on the market.
Who is this for? A family of Uber drivers who relax at home by welding? :)

There's a marginal payback at best to use a couple of powerwalls to do demand response. The powerwalls are further justified for providing some backup power. Spending dollars to chase the marginal savings beyond the standard solar plus battery is almost certainly very uneconomic.
 

miimura

Well-Known Member
Aug 21, 2013
6,176
5,774
Los Altos, CA
Who is this for? A family of Uber drivers who relax at home by welding? :)

There's a marginal payback at best to use a couple of powerwalls to do demand response. The powerwalls are further justified for providing some backup power. Spending dollars to chase the marginal savings beyond the standard solar plus battery is almost certainly very uneconomic.
I think dcbel is trying to do the job that Powerwalls can do, but using the car's traction battery pack instead of stationary batteries.
 

KJD

Supporting Member
Dec 14, 2013
1,310
946
SLC, UT
Yes, a 200A 240V service is a nice round number. I happen to have an empty space in my main panel for a second 200A main breaker. However, if you had a 208V service, you should probably load all three phases. In that case 100A 208V 3-phase is 36kW which should be fed with a 125A breaker.

Many residential 240V service panels are also limited to 125A breakers on the main bus. This is perfect for the available 24kW DCFC units on the market.
Do you know of a 24kW DCFC that is reasonably priced ?
 

mrc3

Member
Jan 2, 2021
17
5
Minnesota USA
Not necessarily, your “mobile” connector would just become the ac to dc converter, just like a laptop charger but bigger, like 50lbs bigger, because you have to up convert 120v to 350-800v.

The other problem is, if you leave your laptop charger at home, you can’t always use your buddy’s charger if he has a different style/brand laptop. I could see a similar issue with a “mini ccs” charger.

The electronics are not that challenging nor that heavy. It is basically one good sized PCB in the Teslas that does the work. Inside the car or in the mobile charger... the job is the same. Probably about 25 to 50% larger than the existing mobile charger.
 
Jan 26, 2020
194
328
Andrews TX
The electronics are not that challenging nor that heavy. It is basically one good sized PCB in the Teslas that does the work. Inside the car or in the mobile charger... the job is the same. Probably about 25 to 50% larger than the existing mobile charger.

Electronics shouldn’t be challenging, but the problems with CCS and multiple brands of EV are proving to be difficult to solve. Brand “A“ charger should work with brand “A“ car though.

I was basing the weight off of a spec I found for a MS gen 2 11kw onboard charger of 35lbs. The onboard charger is liquid cooled, so I figured 15lbs of heat sink/cooling and consumer protection, and you might as well beef up the electronics to handle 20kw. 😎
 

miimura

Well-Known Member
Aug 21, 2013
6,176
5,774
Los Altos, CA
Electronics shouldn’t be challenging, but the problems with CCS and multiple brands of EV are proving to be difficult to solve. Brand “A“ charger should work with brand “A“ car though.

I was basing the weight off of a spec I found for a MS gen 2 11kw onboard charger of 35lbs. The onboard charger is liquid cooled, so I figured 15lbs of heat sink/cooling and consumer protection, and you might as well beef up the electronics to handle 20kw. 😎
It's like two Gen1 chargers. The way I would do the math is to subtract 15lbs of heat sink/cooling, double the rest and then add back the cooling. That comes to 55lbs for 20-24kW.
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,127
7,133
Boise, ID
It is interesting how not cheap this type of product is. The site www.evseadapters.com has had a product on their website for a while that is a small portable fast charging converter. The idea is for like cars that have the really crummy 3kW onboard chargers to be able to use faster sources. So you can put an input like a 14-50 or a J1772 connection into it (10kW or somesuch), and it will convert and output to CHAdeMO or CCS.


But it's about $4,000!
 
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mrc3

Member
Jan 2, 2021
17
5
Minnesota USA
Cool link, and does give representation as to size. Probably with Tesla level quantities cost could be significantly reduced, but still probably $1K or more. But then the relay on my wall in the garage was about that when I purchased it 8 years ago. I would also think size could be reduced as well... but perhaps not enough to be a viable portable unit.

Mike
 

Candleflame

Active Member
Mar 9, 2015
2,669
1,231
QLD, Australia
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.

Tritiums 50kw chargers already only charge a Tesla with 42kw and you also loose 3.5kw per motor from the motors trying to warm the battery until the car reached around 70%. So in reality we see 35kw on those all the time.
 

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