Maximum power for supercharging Tesla Model S?

Matias · Apr 22, 2014

Nissan Leaf has 24 kW·h battery. It can charge at 50kW power. So would Tesla Model S be able to charge with (85/24)x50kW =177kW power?

Nissan Leaf doesn't have liquid cooling for batteries, so one would guess Tesla could do at least same charge rate?

nwdiver · Apr 22, 2014

Matias said:
Nissan Leaf has 24 kW·h battery. It can charge at 50kW power. So would Tesla Model S be able to charge with (85/24)x50kW =177kW power?

Nissan Leaf doesn't have liquid cooling for batteries, so one would guess Tesla could do at least same charge rate?

I'm not an engineer but I'm gonna go out on a limb here and say it's probably a little more complicated than that... just ask the MS owners stuck with an 'A' battery.

techmaven · Apr 22, 2014

The Nissan Leaf has a different lithium ion battery chemistry that tolerates high C charging values better than Tesla's NCA. However, it has much poorer energy density in both specific energy and volumetric density measurements. Further, Nissan has to improve the battery pack to tolerate the high temperatures associated with high C charging which they are reportedly doing. Also, the Leaf reportedly does not achieve 50 kW, that is the nominal value from many of the currently available CHAdeMO EVSEs.

The highest C value that Tesla is using is 1.75, which is the 60 kW pack charging at 105 kW. Presumably that means an 85 kW pack can charge at 149 kW with the same C value. Tesla is currently rolling out 135 kW SuperChargers.

scaesare · Apr 22, 2014

Perhaps that's one of the reason Nissan had to settle a class action lawsuit over cooking it's batteries?

Cottonwood · Apr 22, 2014

techmaven said:
The Nissan Leaf has a different lithium ion battery chemistry that tolerates high C charging values better than Tesla's NCA. However, it has much poorer energy density in both specific energy and volumetric density measurements. Further, Nissan has to improve the battery pack to tolerate the high temperatures associated with high C charging which they are reportedly doing. Also, the Leaf reportedly does not achieve 50 kW, that is the nominal value from many of the currently available CHAdeMO EVSEs.

The highest C value that Tesla is using is 1.75, which is the 60 kW pack charging at 105 kW. Presumably that means an 85 kW pack can charge at 149 kW with the same C value. Tesla is currently rolling out 135 kW SuperChargers.

So maybe 150 kW Superchargers are on the way. That would need 180 Amps, 3-Phase, 480 Volt power. The fancy Square-D breakers they are using are rated up to 100% continuous, have a 200 Amp setting, and the 3/0 cable that feeds the Supercharger cabinet can handle 200 Amps, so this all looks reasonable. The guess is that there are 12 of the single chargers from the car, in a Supercharger cabinet; upping that to 15 or squeezing 25% more power out of the existing modules and 150 kW is very realistic.

150 kW will be useful. It will maybe reduce charge time a couple of minutes for 85 kW "B" packs, but more importantly the second car to arrive, sharing one cabinet, will get more power sooner! A couple of minutes doesn't hurt, but many minutes improvement for the second car will be very nice; it will also improve throughput and reduce possible queueing!

For reference see the Madison proposal with lots of gory detail: http://www.cityofmadison.com/planning/projects/reports/89etm_site2.pdf

Johan · Apr 22, 2014

Also we don't really know the upper limit of the charge port/plug.

Cottonwood · Apr 22, 2014

Cottonwood said:
So maybe 150 kW Superchargers are on the way. That would need 180 Amps, 3-Phase, 480 Volt power. The fancy Square-D breakers they are using are rated up to 100% continuous, have a 200 Amp setting, and the 3/0 cable that feeds the Supercharger cabinet can handle 200 Amps, so this all looks reasonable. The guess is that there are 12 of the single chargers from the car, in a Supercharger cabinet; upping that to 15 or squeezing 25% more power out of the existing modules and 150 kW is very realistic.

150 kW will be useful. It will maybe reduce charge time a couple of minutes for 85 kW "B" packs, but more importantly the second car to arrive, sharing one cabinet, will get more power sooner! A couple of minutes doesn't hurt, but many minutes improvement for the second car will be very nice; it will also improve throughput and reduce possible queueing!

For reference see the Madison proposal with lots of gory detail: http://www.cityofmadison.com/planning/projects/reports/89etm_site2.pdf

The 100th Supercharger uses 135 kW Cabinets, http://www.teslamotorsclub.com/show...Marketplace-NJ?p=620774&viewfull=1#post620774. They are about 90% efficient, and 90% * 150 kW is 135 kW. If we rated Superchargers like we do EVSE connections, then the currently used 135 kW Superchargers would be 150 kW; it's all how you count. :wink:

AmpedRealtor · Apr 22, 2014

You also can't DC fast-charge a Leaf for more than 20 minutes without damaging the battery. According to what I've read, anyway.

David99 · Apr 22, 2014

At a European event Elon talked about the Superchargers and said the maximum charge rate is 'conservative'. I don't remember the exact words, but he basically said the batteries could be charged faster but they are keeping it conservative and (taper it down) because battery life is a higher priority.

green1 · Apr 22, 2014

David99 said:
At a European event Elon talked about the Superchargers and said the maximum charge rate is 'conservative'. I don't remember the exact words, but he basically said the batteries could be charged faster but they are keeping it conservative and (taper it down) because battery life is a higher priority.

I believe he also said that they plan to keep fiddling with it to see if they can't speed things up a bit more (without impact on safety or battery life)
From everything I've seen it looks like 135kW is the most we're going to see for quite a while, but as they adjust more, we may see more to the cabinet to be able to charge more than one car at a time at higher powers, and we may also see the higher power staying for a larger percentage of the charge. Seems they just want to ramp things up slowly so that they know for sure they're not killing the very expensive batteries.

Cottonwood · Apr 22, 2014

Also see [Supercharger protocol for diy CHAdeMO adapter - Page 8. It looks like the wire inside the car is #2 AWG. That dissipates 17 Watts per foot of wire now at the 333 Amp max current of a 120 kW charge rate. If the current scaled, that would mean 375 Amps for 135 kW charging and 417 Amps for 150 kW charging, pushing the resistive heating in the on-board cable to 19 and 22 Watts per foot. I am sure that Tesla did good thermal design and used high temperature insulation, but that #2 wire could be a limit.

I assume that the wiring from the Supercharger to the pedestal need to meet NEC. The car does not need to meet NEC, and the pedestal probably doesn't either. Just to carry 333 Amps per NEC, they need to go to 350 mcm wire between the Supercharger cabinet, and wire size goes up from there at higher currents. My guess is there is a limit to what even Tesla will do to save a few minutes of charge time.

The higher powers will certainly be useful to speed up charge time for the second car to arrive without needing to raise power and current to a single car. Of course, we can hope for that 110 kW-hr battery for the Model X that can accept even higher charge rates...

green1 · Apr 22, 2014

A lot can be done by changing the tapering too so you can keep the same current level you have now, but for longer in to the charge, I think we will see that as Tesla gets a better idea as to how much they can get away with safely.

wk057 · Apr 22, 2014

I'll see if I can pull some pics from my dash cam from when I visited the Hamilton, NJ supercharger while under testing ( Supercharger - Hamilton Marketplace, NJ - Page 6 ). They had the tops of some of them open (not visible in any of my pics) showing the connections inside the top to the actual visible cord.

Check out this full res image and look at the wiring in the bottom going to the ground (which come up at the pedestals): http://vpn.wizkid057.com/nas/tesla-sc-hamilton/20140415_152442.jpg

The wiring is *huge*. I did ask how large it was (and forget the answer...) but it was something like a full 1/2" thick.

The wire for the actual visible cable is much thinner than the SC->Pedestal wiring however, but still thick...

wk057 · Apr 22, 2014

Cottonwood said:
Also see [Supercharger protocol for diy CHAdeMO adapter - Page 8. It looks like the wire inside the car is #2 AWG. That dissipates 17 Watts per foot of wire now at the 333 Amp max current of a 120 kW charge rate. If the current scaled, that would mean 375 Amps for 135 kW charging and 417 Amps for 150 kW charging, pushing the resistive heating in the on-board cable to 19 and 22 Watts per foot. I am sure that Tesla did good thermal design and used high temperature insulation, but that #2 wire could be a limit.

I assume that the wiring from the Supercharger to the pedestal need to meet NEC. The car does not need to meet NEC, and the pedestal probably doesn't either. Just to carry 333 Amps per NEC, they need to go to 350 mcm wire between the Supercharger cabinet, and wire size goes up from there at higher currents. My guess is there is a limit to what even Tesla will do to save a few minutes of charge time.

The higher powers will certainly be useful to speed up charge time for the second car to arrive without needing to raise power and current to a single car. Of course, we can hope for that 110 kW-hr battery for the Model X that can accept even higher charge rates...

I'm going to note that I believe this info is based on the euro version, which has more conductors. It's entirely possible the US version has heavier wire.

Cottonwood · Apr 22, 2014

wk057 said:
I'm going to note that I believe this info is based on the euro version, which has more conductors. It's entirely possible the US version has heavier wire.

The picture that started the discussion was from Europe, but the post with the #2 AWG reference is from California.

- - - Updated - - -

wk057 said:
The wiring is *huge*. I did ask how large it was (and forget the answer...) but it was something like a full 1/2" thick.

Exactly, 1/2" diameter copper is 250 mcm wire, which the NEC says will carry 290 Amps with the insulation that Tesla calls for. 375 Amps needs 400 mcm wire, and it just keeps going up from there.

martinwinlow · Apr 24, 2014

For what it is worth, Chademo charging my i-Miev (Lithium Titanate - Li2TiO3 - chemistry) starts out at 120A x 360V = 43kW when the SOC is at or near 0%. This then slowly reduces as the charge level goes up, giving 65A at 60% and 25A at 82% where it stops (after about 30 minutes from empty). If you want to go higher than 82% you have to start the charger again and it gets even slower. Another 10% takes 15 minutes more. Never done a 0 to 100% charge to know how long it takes. MW

tom66 · Sep 25, 2014

Cottonwood said:
For reference see the Madison proposal with lots of gory detail: http://www.cityofmadison.com/planning/projects/reports/89etm_site2.pdf

One interesting thing to note about this is that Tesla sense the temperature at the plug directly. So it seems reasonable they could increase the ampacity of the design by limiting the plug temperature. Does anyone notice the supercharger plug getting especially hot? (Given the HPWC plug complaints I'd expect it. The HPWC is only 80A vs 330A though...)

islandbayy · Sep 25, 2014

1 Minute 48 Seconds should answer many questions for you all on the kiosks

Cottonwood · Sep 25, 2014

See Limits of Model S charging ? - Page 4 for all the reasoning...

... the bottom line:

This appears to be strong evidence that the existing Superchargers and/or the existing cars are limited to a maximum charging current of 333 Amps by wire and connector design. Further, the existing chargers appear to be limited to a maximum battery Voltage of 400 Volts. Even if the maximum current could be used at the maximum Voltage (very difficult) that creates a limit of 133 kW. With the existing Model S, that is about 443 rated miles per hour, only slightly more than the existing 120 kW, 400 rated miles per hour limit.

David99 · Sep 25, 2014

Has anyone been able to charge at more than 120 kW? I know Tesla mentioned 135 kW, but I think it's the maximum combined power output of a Supercharger when two cars are connected. I have yet to see anyone actually getting more than 120. In my 6 months of ownership and charging at more than 20 different SC I have never seen more than 120. Mostly only 115. Only very few times was it 120 for a few minutes.

Maximum power for supercharging Tesla Model S?

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