I'm not sure why you think I said this... maybe I mistyped something. There are 96 cell pairs in the LEAF, and each is charged to 4.1 volts (plus or minus about 50mV or less, 393.6 volts total). They can discharge until the lowest cell pair reaches about 2.9 volts.
Assuming a depleted battery pack at just below 300 volts, the CHAdeMO charger is instructed by the car through the CAN bus to first charge at 388 volts, increasing to 394 volts at 120 amps continuous until about 50% SOC, then it ramps down the amperage to until the charge is complete.
This is where we are failing to understand each other. I'm not sure if we are disagreeing over facts or just failing to communicate, so I will try to re-state my argument more clearly.
With DC charging, the charger can't fix both the current and the voltage at the same time: the relationship between voltage and current is defined by the cells, varying significantly with state of charge but also other factors such as temperature, age, and random manufacturing variations from cell to cell. So either the charger fixes the current and lets the voltage turn out to whatever the cells let it be, or it fixes the voltage and lets the cells determine the current. Common practice is to have both a current limit and a voltage limit: when the charger is first turned on, the terminal voltage is whatver the pack's resting voltage was and the charger then ramps the voltage until it hits either the current limit or the voltage limit. If it hits the current limit, then you are in the constant-current regime and the voltage will be less than the target voltage: as the charge proceeds, the current will stay the same and the voltage gradually rises. If the voltage hits the voltage limit (either straight away or after a period of charging) then the current will be less than the target current, and will fall further as the charging proceeds.
So, with a given voltage/current limit you are never delivering the maximum current at the same time as the maximum voltage, and so it's not accurate to calculate the maximum output power of a charger (or, as we were discussing here, the connector) by multiplying max current by max voltage. How close you can get depends on the pack/cell characteristics, so it is interesting to look at the available numbers to see whether this effect is just a minor technicality (a few percent) or if it in fact limits these connectors to a significantly lower power than the datasheet numbers suggest.
We both agree that current packs (both LEAF and Tesla) are "wasting" some of the connector's theoretical capability by having a peak pack voltage during charge less than the connector/charger limit voltage of 500V - somewhere around 20% (400V vs 500V). Obviously some margin is needed to account for component tolerances, overshoot etc. - it's not clear whether the current pack designs have left this much margin deliberately, or whether it's simply a case of the pack voltage being determined by other considerations unrelated to charging.
However, within the 0-400V range that they have decided to use, the peak output power still isn't the connector/charger's maximum current * 400V, since the voltage while drawing peak current will be less. I would have expected the cells to have started charging somewhere around 3.5V per cell, and still be well under 4.0V by the time the current is tailing off. This seems to be borne out by results for Model S (eg.
http://www.teslamotorsclub.com/showthread.php/12078-Typical-Supercharging-rate?p=262066&viewfull=1#post262066), where the peak current is only achieved between about 365-375V as against an end-of-charge voltage around 405V. So this pack could only draw 375*200 = 75kW out of a hypothetical CHAdeMO/J1772-DC high power charger, or if you built a higher voltage pack out of the same cells to use the whole voltage range you might get that same peak at 450V, giving an absolute max using the CHAdeMO or Frankenplug connectors of 90kW - and an average much worse than this.
Your LEAF numbers, taken at face value, suggest that the LEAF's cells have a much flatter charging profile and hence a bigger pack made out of the same cells could make better use of a 200A-limited plug. However, I was suspicious whether that was a real difference in the cell characteristics or misleading information from the charger display - it seemed unlikely that the cells actually stayed at constant current and constant voltage over much of the charging time, and I was speculating that the charger was showing the limit voltage requested by the car rather than the actual instantaneous voltage.
I don't quite follow this. Are you saying because the Frankenplug block has proposed a charging standard, somebody "has" to use it? How about if I proposed a standard? The DC charging infrastructure is plenty viable in the areas where it is deployed, and getting moreso daily around the world. Frankenplug currently isn't even a player, nor do I feel obligated to spend my tax money to make them one.
No, I was saying that with Tesla having taken a large market share with cars that are not CHAdeMO compatible, the charging industry needs to do something about it. Admittedly "something" doesn't necessarily have to be installing Frankenplugs. Unfortunately, there's a number of options, all of them less than ideal. I think I was too positive about Frankenplug in my previous remarks, but I still think you are equally too negative about the actual prospects (even if it is an evil political stitch-up, the bad guys do often end up winning...).
It really needs Tesla to declare their hand on adapters.
If Tesla will license their Supercharger protocol, and supply the charging nozzle, I'd be pretty excited to offer that option. There will be hundreds of thousands of Tesla cars running around in the coming years to use it. I don't see any similar market for any of the proposed Frankenplug cars; eGolf, Spark EV, BMW i3. Heck, virtually all of the current cars that aren't Nissan or Tesla have no DC charger capability at all.
Well, they have said all along that the Supercharger protocol is simply J1172-DC, so assuming that they are telling the truth then it's just down to the connectors.
If Tesla manage to come up with a cheap/small adapter for Frankenplug, then that may still be the way to go: you don't have to license anything from Tesla, the experience for Tesla customers is still good, and you are covering your options against other Frankenplug cars coming along later. If tax dollars are involved anywhere, they probably prefer something non-proprietary even if it's not the best engineering solution (avoiding allegations of 'subsidising Tesla', whether fair or not).
On the other hand, if that adapter turns out expensive and/or big, then I agree it's a non-starter: no amount of future-proofing or political acceptability can justify something that people won't want to use.
If a way can be found to solve the locking issue and do J1772-DC-lev1 with the existing adapters, that may be a good way to go for lower-capacity (up to 30kW) chargers.
Otherwise, it's a case of sourcing the Tesla connectors. In extremis, 80A (==30kW) capable ones are available by buying HPWCs. Although it would probably be unwise to try to do this against the will of Tesla, just getting them to sell an existing part (the tail off the HPWC) with the tacit agreement you are going to build it into a DC charger has to be a much easier negotiation than getting them to supply you a complete charging solution (that they don't have time to develop), the Supercharger cables (which are bigger than wanted for the job and need the accompanying pedestal to support them, hard to integrate into existing CHAdeMO locations), or a custom-design connector/cable for 120A (again, design work).
If only stations are going to offer a charger adapter, the actual adapter would be in EXTREMELY low volume and be really expensive.
I only partly agree with that. Obviously a station-only adapter is low volume by definition, but the portable one will also be relatively low volume and much harder to do well: in particluar, the compromises necessary to build it in low volume at sensible price are much less of a problem (and in some ways a benefit) for the static adapter.
The static adapter can use a simple steel housing (possibly an off-the-shelf pedestal unit, wall-mount box or similar, otherwise something in folded steel that's easy to design and make in any volume), and off-the-shelf panel-mount CHAdeMO socket. Such a thing would be a complete boat-anchor and highly unattractive as an adapter to carry in the car, whereas it's exactly what you want for a static adapter. To make a decent portable adapter you are almost certainly looking at significant tooling for mechanical parts - which does mean a lot of cost unless the volumes are high.
Even the electronics may work out cheaper - I'd initially assumed this would be equivalent regardless of the type of adapter, but in fact I see there are people selling daughter cards for the GreenPHY PLC (which is the only difficult part of the job) - so with space inside the 'boat anchor' it might be possible to do it by integrating off-the-shelf parts rather than a complete custom design.
Approvals are also an issue - but with a large, low-volume device you can afford the luxury of belt-and-braces design and/or quick fixes to problems found in testing, while with a tightly-engineered portable unit you risk blowing that investment in mechanical tooling to fit in what are otherwise simple electrical fixes.
And all of this assumes it is done as an independent adapter, rather than the charger manufacturers offering it as a second head on their charger designs. Those that already claim to offer a Frankenplug option are already 90% of the way to offering a Tesla option. Mind you, it would probably be worth funding development of the standalone adapter just to keep the charger manufacturers honest on the pricing of Tesla/Frankenplug upgrades, which otherwise risk being the classic case of variation-order overcharging.
