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SAE vs CHAdeMO
- Thread starter TEG
- Start date
The issue is current (amps), not necessarily power (volts * amps) though they are related.
SAE Combo DC connector are expected to be rated for up to 450V/200A (90kW), though I believe that most of the ones will be limited to 125A.
CHAdeMO connectors on the market are currently rated for 500V/125A (62kW), though the connector is designed to handle up to 200A.
The Tesla Supercharger currently pushes around 250A maximum. If Tesla wants to push up to 120 kW through them, they will have to bump the allowable current up to 300A throught the connector.
Talking in terms of power rather than current makes for a complicated answer, but "less than the Tesla connector" is the short version.
SAE DC is specified at max 200A, max 500V (or 80A through the existing J1772 connector rather than the 'frankenplug'). But in a practical charging system you never achieve max current and max voltage at the same time, so the answer is not 100kW. For a Model S, the bulk of the fast charging occurs around 360V, so that would be around 72kW max through an SAE DC charger (or 29kW through an SAE DC with the smaller connector).
A theoretical car with the battery voltage picked to optimize SAE DC charging (rather than any other considerations) might get up to 90kW on the SAE DC connector.
CHAdeMO has similar theoretical limits to SAE DC, with the story confused by the fact that actual deployed connectors generally have a lower rating - this is largely because there's no point putting a 200A-rated connector on a 125A-max charger.
stopcrazypp
Well-Known Member
And they haven't built any 200A rated connectors because all the chargers thus far are 125A:
http://www.chademo.com/wp/items/#.pdf
There's been reporting that there are 90kW SAE DC chargers in testing by GM and BMW although no confirmation of what company and the specs. We'll know when UL listing is done and a spate of production chargers get announced.
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I would love to know this too, but only Tesla would know this. If some one is able to accurately measure the contact surface of the connector, it might be possible to guess. Also if anyone looks at the wiring for the power pins in side the car, it'll be possible to know the car's limit (although not necessarily the same as the connectors).
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It should be relatively easy to built an adapter that allows a CHAdeMO vehicle charge off an SAE DC charger or Supercharger. The CHAdeMO socket has more pins than necessary. Just assign them accordingly.
However, for the other way around: a Tesla or SAE DC vehicle charging off a CHAdeMO charger, it's impossible for just a "pass through" physical adapter. This is because there's simply not enough pins. CHAdeMO uses all 8 of its signal pins for the handshake to occur successfully. Tesla's connector only has 3 signal pins, SAE DC has 5 (if you count the 2 unused AC power pins). And for the CAN messages, it must pass through the two dedicated CAN pins on the CHAdeMO side. PLC passes through the chassis ground pin. You can use one of the CAN pins as a chassis ground, but you can't use the chassis ground to transmit CAN because you need both pins (a high and low).
ZBB
Emperor
I put a couple phrases in red -- so this question is about the use of the "regular" J1772 connector with SAE DC.
Would this possibly work today using the existing Tesla J1772 adapter? While still slower than a 90kW Supercharger, being able to get 29kW DC would be a welcome speed improvement over a 30A / ~6kW J1772 public charger (or should I say 17A / ~3.3kW since Blink has derated their units due to overheating)... Would fully charge a 60kWh Model S in ~2 hours (yeah yeah, I know it will slow down for the last 10%)...
Obviously, you'd need to find a SAE DC charger with the regular J1772 adapter and not a CCS / Frankenplug...
ZBB,
It sounds like a good bit of work. You mention the Public J1772 chargers, and Blink; It's important to remember that those that have installed these chargers have chosen to put in 3/6 kW systems rather than just a 17-20kW system. These 17-20kW J1772 systems exist now without the trouble of developing a SAE DC system, or a conversion to the Tesla DC standard, but the US install base has chosen not to (for various reasons). A perfect example of a 20kW J1772 system is Tesla's own HPWC, and Sun Country's network in Canada. I've been lucky enough to use the Public 70-80A J1772's in Canada, and I think that simply rolling these out in the US would be the largest bang for the buck.
Peter
It sounds like a good bit of work. You mention the Public J1772 chargers, and Blink; It's important to remember that those that have installed these chargers have chosen to put in 3/6 kW systems rather than just a 17-20kW system. These 17-20kW J1772 systems exist now without the trouble of developing a SAE DC system, or a conversion to the Tesla DC standard, but the US install base has chosen not to (for various reasons). A perfect example of a 20kW J1772 system is Tesla's own HPWC, and Sun Country's network in Canada. I've been lucky enough to use the Public 70-80A J1772's in Canada, and I think that simply rolling these out in the US would be the largest bang for the buck.
Peter
Well, in theory yes, but there is a snag: with J1772 DC, you are meant to have mechanical locking on the car side to retain the connector (preventing you from unplugging while the power is on: this feature is optional for AC but mandatory for DC, presumably due to the greater potential for arcing). Tesla of course do have locking, and very likely follow the parts of the protocol that control the locking, but it only retains the adapter and not the J1772 connector.
If they had made the adapter with a clip on the top so you couldn't disengage the J1772 while the adpater is mated to the vehicle (rather like Babylon5's locking ring, but they could have done it better as an integral part of the adapter), then this would all have been easy. As it is, they have a problem and it's not obvious how they resolve it.
I also think that J1772-DC level1 has potential - it gives a useful rate of charge, is potentially easier to find a source of power for than an 80A AC EVSE which may offset the cost of the DC charger (it is probably easier to find 25kW worth of 3-phase 'spare' in an industrial location than 80A of single phase, so if the DC charger can piggy-back on an existing installation rather than needing a new utility install, then that's a significant cost save). On the car side it avoids the need for the second charger, and can give the full 29kW even off a 208V supply (where even twin chargers are down to 208*80 = 16.6kW).
It's notable that at least a few CHAdeMO sites are only 25kW.
However, none of the car manufacturers or charger vendors seems to share my enthusiasm - I've not seen any mention of this stuff anywhere outside the standards document, so it may well never happen.
Actually, it probably wouldn't need to slow down for the last 10%, as it's barely above what a HPWC on full bore (at 240V) can deliver.
ZBB
Emperor
I realize the existing J1772 AC chargers cannot handle DC charging... I only mentioned Blink since I live in their "territory" and have experienced their limitations -- their chargers at my office are not installed properly and used to trip a breaker at anything over 24A charging. But they've further de-rated them since last week due to the overheating issue they acknowledged last week (where they have damaged some customer cars) -- so the units at my office now max out at 17A.
I was just thinking that in the absence of a Tesla adaptor to the CCS or CHAdeMO that if it was possible to get 29kW DC with the existing J1772 adapter...
As for 20kW AC -- please remember that requires the optional 2nd charger on the Tesla... I only have the single charger -- so 10kW AC is my cap...
stopcrazypp
Well-Known Member
As arg points out there's that locking connector requirement, but also a small slot in the plastic of the adapter that makes it so the current adapter won't work:
http://www.teslamotorsclub.com/show...1772-DC-(Combo)-Connector-Adapter-for-Model-S
However, something very similar to the existing one should work (with the locking mechanism added and a small change to the plastic slot). As I mention in that other thread, I expect such an adapter to be included standard (it'll be compatible with both J1772 AC and "Level 1" DC). There'll be another different, likely optional, adapter that'll be compatible with DC "level 2" (but won't support AC charging because of how the pins have to be routed).
That's a bit too handwavy for me. I don't buy the underlined assumption is straightforward. Who's to say the SC doesn't treat a low amperage request as a battery fault and refuses to do any charging at all? For example.
Because as others have stated, the SC is already capable of low current - it drops under 10 kW (less than 25A) at the end of a range charge.
Was just one example. Some people jump to "no problem" pretty quickly when it's often never easy and sometimes not possible. Heck, just getting reliable gennie charging for the Model S is a challenge. Talk to Roadster owners about how easy it is to get a SC working with their cars.
Well, Tesla have said that the Supercharger is just SAE-DC with a different plug, and there's no reason to disbelieve them, especially when you read the standard and see that everything they need is there (including hooks for authentication), with most of the intelligence being in the car. So you would expect other SAE-DC cars to be able to charge with the right connector.
That's AC charging, not DC, and good quality generators that produce a good sine wave are not always easy to find. It's a common problem.
Huh? The Roadster isn't even capable of DC charging out of the box. That said, there are people who have modified their LEAF to accept additional high voltage DC (effectively DC QC by installing 1 or more chargers and injecting additional DC directly into the battery) and people who are reverse engineering CHAdeMO, so it should be possible to directly DC charge the Roadster with the right knowledge.
Sigh. My point, again, is that very few things in live are easy or "just work" without some significant effort.
I don't think that anyone is implying that it won't require significant knowledge of both the vehicle and the QC protocols involved...
Note, any reports of the death of CHAdeMO here are grossly over-exagerated. There are now a couple of hundred sites installed or opening shortly in the UK alone and not one Combo charger.
Tesla would be daft not to include the CHAdeMO adapter here.
At least one MEP (Member of the European Parliament) has said that she will make sure any wording in this bill includes provision for CHAdeMO.
Tesla would be daft not to include the CHAdeMO adapter here.
At least one MEP (Member of the European Parliament) has said that she will make sure any wording in this bill includes provision for CHAdeMO.
stopcrazypp
Well-Known Member
Well the draft does say a transition period between now and 2018 (where dual connectors stations will be encouraged). So it's not going to happen immediately. IEC 62196-3 (which includes CCS) has its final release scheduled for December this year, so obviously there will not be CCS stations installed in the EU before then (outside of Germany, which already has adopted CCS independent of IEC).
About the CHAdeMO adapter, according to Kevin, the UK would not allow such an adapter because IEC 61851-1 states: "Adaptors shall not be used to connect a vehicle connector to a vehicle inlet". So the legislature has to work to change that part of the electrical code or Tesla would be selling a code violating adapter (has various legal and insurance related issues).
http://www.teslamotorsclub.com/show...nnector/page47?p=195461&viewfull=1#post195461
But then Tesla went with a Type 2 socket for Europe precisely because of this kind of ban and if they had the ability to lobby the governments or IEC to change it, they would have done so already. And unlike Mennekes stations, there no hope of getting around this with stations that have a socket with no cable, because all CHAdeMO stations come with the cable. Not sure what they will do about that adapter (maybe sell it outside EU and let consumer carry the risk?).
I don't think you understand how DC charging works. The roadster does not have a high voltage junction box. Unless someone redesigns a new PEM with a HV junction box, AND writes code to run that PEM, there will be no DC charging for roadsters. That is one expensive endeavor, since there were only 2500 cars produced.
It would be much smarter and cheaper to just retrofit a Model S setup(motor, gearbox, inverter, charger, etc) into the roadster.
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