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TonyWilliams
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Re: First DC Station capable of charging at a rate of up to 350 kW, operational by 6/17?

Sat Jan 07, 2017 3:55 pm

sendler2112 wrote:
powersurge wrote:Somehow, I cannot imagine that a 350kw charger will be in our lives for a VERY long time. Isn't this pie-in-the-sky fantasy?

Darn, we are still at 6.6kw charging... How could anyone even imagine that we will be able to charge our Leafs in 2 minutes in the near future????.....

Yeah and I want a Jet Pack to go to work..

Tesla charges at 110kW now. Porsche will be charging at 300 next year.


Just to be clear, Porsche has never said their vehicle will except 350 kW of power. They may have said it will be able to use a charging station that is capable of 350 kW, but then so is a Nissan LEAF or a Mitsubishi iMiev.

I’m going to be saying this a lot in the coming years, the placarded maximum charge rate of the station has very little to do with how fast it will charge your car.

A Tesla charge station can DC output 365a * 400v = 147kW, yet no Tesla car can charge over 120kW. Those same cars absolutley can charge at either 365a, or 400v, just not at both the same time.

The same is true of a Chevy Bolt EV, Nissan LEAF, BMW i3, or eGolf, or any number of other vehicles restricted to 125a. Virtually all public DC charge stations are physically capable of 500v, but no car Is.

So, while the charger is technically capable of 125a at 500v = 62.5 kW, all those cars listed above charge below 50 kW. Why? Because none of the cars are capable of more than 400v. In addition, none of them are capable of handling the rated 125 amps at their max battery voltage. Again, no car is charging at 125a * 400v = 50kW (well, there is one… the Tesla Roadster with a 416v battery).

It’s quite probable that should the CCS group ever publicly release their data, we will find that the maximum amperage is 400 and the maximum voltage will be 850 to 900:

sendler2112
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Re: First DC Station capable of charging at a rate of up to 350 kW, operational by 6/17?

Sat Jan 07, 2017 4:04 pm


GRA
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Re: First DC Station capable of charging at a rate of up to 350 kW, operational by 6/17?

Sat Jan 07, 2017 4:18 pm

TonyWilliams wrote:<snip>
It’s quite probable that should the CCS group ever publicly release their data, we will find that the maximum amperage is 400 and the maximum voltage will be 850 to 900:

Per the Chargepoint spec sheet (back one page), the max. for their new unit is 400A @ 200 - 1,000V. If a Mission E has an 800V battery, it will have max. charge rate of 320kW. It would take a further boost in pack voltage by some manufacturer to get the full 400kW. Chargepoint is future-proofing to some extent by allowing a max. voltage of 1,000, even though no car known to be in development at this time can use that.
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arnis
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Re: First DC Station capable of charging at a rate of up to 350 kW, operational by 6/17?

Sat Jan 07, 2017 8:40 pm

lorenfb wrote:
So you're stating that a battery charge rate (amps) has no effect on the battery's temperature change, i.e. a .1C versus
a 1C rate results in the same temperature change over the same time, right?


What I said that there is no constant due to air humidity factor that is almost never mentioned.
Charging battery at .1C to full and 1C to full will have slightly different efficiency. Slightly different heat output if we sum the whole charge cycle.
Due to tenfold time difference peaking temperature will be different and efficiency difference will not be even noticed.
Short range EVs <30kWh -- Medium range: 30-60kWh -- Long range: >60kWh
Charging: Trickle <3kW -- Normal 3-22kW -- Fast 50-100kW -- Supercharging >100kW

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TonyWilliams
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Re: First DC Station capable of charging at a rate of up to 350 kW, operational by 6/17?

Sun Jan 08, 2017 1:48 am

GRA wrote:
TonyWilliams wrote:<snip>
It’s quite probable that should the CCS group ever publicly release their data, we will find that the maximum amperage is 400 and the maximum voltage will be 850 to 900:

Per the Chargepoint spec sheet (back one page), the max. for their new unit is 400A @ 200 - 1,000V. If a Mission E has an 800V battery, it will have max. charge rate of 320kW. It would take a further boost in pack voltage by some manufacturer to get the full 400kW. Chargepoint is future-proofing to some extent by allowing a max. voltage of 1,000, even though no car known to be in development at this time can use that.


I think you are confusing the charger performance specs with the protocol specs. Yes, the ChargePoint charger has limits of 400a and 200-1000v. They are mistakenly calling that "400kW", even though no car would ever charge at that speed.

Currently, the CHAdeMO spec maximum is 350a / 50-1000v.

CCS has not publicly released their specification, but it's becoming more clear that is is likely also 350a, but also a duty cycle limited 400a. A company called Phoenix Contact has produced a liquid cooled pin set in the plug to handle the limited 400a.

As far as the maximum voltage for CCS, we just don't know... 850, 900, 1000??? We don't know. The minimum voltage is probably 200 or 250.

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RegGuheert
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Re: First DC Station capable of charging at a rate of up to 350 kW, operational by 6/17?

Sun Jan 08, 2017 2:11 am

A couple of predictions:

1) BEV battery voltage will move rather quickly from the current range near 400V to 800V or above. Why? Because higher voltage is simply better than higher current for power electronics (and for batteries). At 800V, the power switches will move from Si IGBTs to SiC MOSFETs. This will improve efficiencies of both the chargers and the drive electronics.
2) Charging at-or-near 350A will take quite a bit of time to become commonplace. There will be problems with overheating and fires early on. Simply put, it is a challenge to make the resistance low enough in connectors and crimps in consumer products at such high current levels. It also takes a lot of copper.
RegGuheert
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arnis
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Re: First DC Station capable of charging at a rate of up to 350 kW, operational by 6/17?

Sun Jan 08, 2017 7:17 am

I don't think that packs above 1000V are reasonable for road transportation.
800V, yep. Possible. Still I think that 400V will be preferred for low range EV-s.

250kW-350kW charging (whatever voltage) will most likely not happen in few years on cars.
Heat extraction from pack not doable AFAIK.
Short range EVs <30kWh -- Medium range: 30-60kWh -- Long range: >60kWh
Charging: Trickle <3kW -- Normal 3-22kW -- Fast 50-100kW -- Supercharging >100kW

sendler2112
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Re: First DC Station capable of charging at a rate of up to 350 kW, operational by 6/17?

Sun Jan 08, 2017 7:41 am

RegGuheert wrote:A couple of predictions:

1) BEV battery voltage will move rather quickly from the current range near 400V to 800V or above. Why? Because higher voltage is simply better than higher current for power electronics (and for batteries). At 800V, the power switches will move from Si IGBTs to SiC MOSFETs. This will improve efficiencies of both the chargers and the drive electronics.

Availability of affordable large value capacitors over 600v is what has dictated the 400v standard we have now. Even to a progressive company that stakes it's claim to fame on high charge rates like Tesla.
Last edited by sendler2112 on Sun Jan 08, 2017 8:33 am, edited 1 time in total.

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RegGuheert
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Re: First DC Station capable of charging at a rate of up to 350 kW, operational by 6/17?

Sun Jan 08, 2017 8:06 am

sendler2112 wrote:Availability of affordable large value capacitors over 600v is what has dictated the 400v standard we have now. Even to a progresive company that stakes it's claim to fame on high charge rates like Tesla.
Interesting. Thanks!

Is this issue mainly for the charger? The drive inverter is 3-phase, which greatly reduces the need for capacitance. I'm familiar with quite a few designs up to about 10 kW, but perhaps at 10X to 30X the power it's a much bigger issue.

The charger is single phase (at least in this country), so much more capacitance is needed. Doesn't everyone use electrolytics for the charger today, even at 400V?
RegGuheert
2011 Leaf SL Demo vehicle
2011 miles at purchase. 10K miles on Apr 14, 2013. 20K miles (55.7Ah) on Aug 7, 2014, 3K miles (52.0Ah) on Dec 30, 2015, 40K miles (49.8Ah) on Feb 8, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

sendler2112
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Re: First DC Station capable of charging at a rate of up to 350 kW, operational by 6/17?

Sun Jan 08, 2017 8:57 am

I'm seeing plenty of high voltage FETs now so I am assuming the voltage rating of the caps are the hang up to increasing the pack voltage although I haven't looked at a schematic of the charger or motor controller to see how much capacitance is really needed. Large format electolytic caps above 650v are still quite rare.

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