how do the cables work technically?

[felixtb]

This might have been discussed in other posts before me but i am a little confused of how the different cables differ and actually work to make sure that you charge at a correct amperage and possibly voltage........? HPC to TESLA: a Controled signal between the charge point and the car, supplying known 70A. UMC also contoled but here it is the gizmo box on the cable that makes sure the right amps are signaled to the car? the spare connector there is no intelligence and the car defaults to 10-16A of charging? how does this all work if one imagines a Mennekes or a J1772 connector? does one need the little gizmo box from the UMC to control the amperes? or does the signal give enough info from the charging point to automattically tell the car what power is coming in so that there is no overcharging etc....??

these questions lead up to another one. if there is intelligence there, then could one not conceivably buy a couple of spare connector cables to get to the TESLA connector and then have RWE and some company doing official cables with J1772 connectors, or something like that, help us make new charging cables from this?? if one looks at the price of just a Mennekes plug they seem to run about $200 so yes first paying $600 for a spare connector and then another 200 and then probably another 500 or so for the pro job is more than just the parts but still about the same as a new UMC and that to me would still be worth it, if what I am thinking, cable intelligence wise, is correct. please help me understand if I am on the rifght track or completely of the base......?

thanks for the help on this.

 

[TEG]

Someone will probably give a better answer, but here is a start:

Yes, there is a signal that can tell the vehicle what AMPs it is suggested to draw when charging.
Without any such signal it will default to ~15amps. So in USA, you can have the "takes forever to charge" emergency cable that plugs in basically anywhere and uses the standard USA 120V@15A household outlet.

It doesn't get any signal from the wall, and has no mechanism to generate its' own signal. In most parts of Europe you are a little lucky for default EV charging because standard household current tends to be 240V. So you can use a "straight through" cable with no signal and get twice as much power because you are getting 240V@15A instead of USA 120V@15A.

If you have an HPC, you can configure it to send a signal to tell the Roadster that it is allowed to draw more current. The signal can be configured to offer various increments such as 24A, 32A, 40A, 48A, 56A, 64A, 72A. It is up to the installer to set it to a rate that doesn't exceed the circuit breaker rating (~1.25x the amperage) or the wiring leading to the HPC. If for some reason you want the Roadster to use less current than the HPC "advertises" you can use the VDS in the Roadster to force a lower setting.

The original Tesla MC240 had a fixed signal generator that would tell the Roadster that 24A was available.

It was a somewhat conservative level since some NEMA14-50 plugs could offer more, but they pre-set it to a level likely to be safely available on any NEMA14-50 you might find.
(I am speaking of the USA version, I am not sure if the UK/Europe version was the same.)

Then there is the RFMC and Tesla Universal Mobile Charger.

Those will vary the signal based on the type of cable plugged into the twist lock end.

The different cable types have different components (such as a diode) built into it so the box knows that type of plug is on the end.
Based on the type of plug it will tell the Roadster that there is an appropriate current level available somewhere in the range of 16-40amps.
They have this chart for the USA plug options:

If you "know better" and know that there is a plug with "sub-standard" wiring or breaker, you can use the VDS to lower the charge current as necessary.

Hopefully this helps some, and hopefully I was accurate with my description.

 

[TEG]

And yes, someone could make a box with Tesla connector on one end, and another plug (Mennekes or J1772) on the other end and have an RFMC/UniversalMobileConnector type signal generator board inside to tell the Roadster what current you want to offer. In theory one could have a rotary switch, or buttons to manually select what current level to advertise. So far, the mobile adapters have resisted having that level of manual control like what you can do when configuring the HPC.

 

[felixtb]

thanks TEG. i was wondering about the cables for the Leaf, for example, where there is no gizmo box between the connectors, like on the UMC. does the leafs on board charger behave differently than the TESLAs or is it not necessary with the in-between box if the signal from the charging station, as with the HPC, does the job. and would the RWE and other charging stations do this job. therefore effectively eliminating the need for the UMC in most cases did one have a, for example, Mennekes to TESLA cable, similar to the one shown in the video clip from holland in another recent thread?

 

[TEG]

The Leaf's onboard charger is only capable of pulling 15amps max so it is a moot point. I don't know if it even bothers to look for a signal since it only charges at the lowest ampacity rate.

On the other hand, the Leaf can also be ordered with a high speed DC charge port that can charge more quickly than the HPC if you get to a CHAdeMO high speed offboard charger.
At the moment, in the USA, the CHAdeMOs are so rare that it is not much more than a novelty at this point. Hopefully they eventually deploy a bunch in locations that make it useful for medium distance road trips. For now the Leaf is a poor road trip car because: The J1772 only charges at a relatively slow rate, and the CHAdeMO chargers are nearly non-existent in the USA right now. I think it was stated that they are more plentiful in Japan which would make the Leaf have more utility there.

 

[felixtb]

actually just took the Leaf as a point of departure since the cable in the video from holland was for a leaf. but that also explains why it may not need an intelligent box in between the car and the proposed charging station..... so the question is really if I want to have poduced a cable with Mennekes or J1772 connectors one end and TESLA the other I should use the UMC cable and jumpers from it...... and not the plug from a spare connector re matched to a Mennekes or J1772 plug on the other end? (obviously with appropriate cable in between)

 

[TEG]

Question: Can the Roadster VDS be used to pull MORE current even if there is no signal on the charge cable?
I know it can be used to lower the rate (to less than the signal says should be available), but can it work the other way so you could tell the Roadster to grab 40amp from a cable with no max current signal?

 

[doug]

Yes, I would think a "straight through" would only get you 15amps.

No, they (i.e., Tesla, Yazaki J1772, and Mennekes type 2) are all basically using the same communication protocol. A straight through would pass the current availability signal from the EVSE to the car. No UMC signal generator box necessary. There are also some passive components in the cable to indicate how much current it's able to deliver. That means the max current could be 70 Amps or whatever the single phase limit is for Mennekes.

 

[felixtb]

so if one did buy a spare connector from tesla for 600 and then asked a professional to disasemble it and only keep the tesla plug. then same professional assembles a new appropriate leade and a Mennekes or J1772 to the other end and voila we have a workable cable that signals the correct current from the EVSE!?.......

 

[widodh]

so if one did buy a spare connector from tesla for 600 and then asked a professional to disasemble it and only keep the tesla plug. then same professional assembles a new appropriate leade and a Mennekes or J1772 to the other end and voila we have a workable cable that signals the correct current from the EVSE!?.......

Yes, correct! EV-Box in the Netherlands could do so.

 

[doug]

Essentially... there are a few wrinkles, though. We have a few threads on the topic. Start with this one.

 

[AndrewBissell]

The problem is the spare cable has conductors (metal wires) sized for 15A or so. Thus your professional would resistor code the cable and when plugged in to a Mennekes-style EVSE capable of 70A, the EVSE would note the 15A coding of the cable and only offer the signal to the car for 15A charging.

Obviously if you started with an MC240 cable you could code that for 30A (probably 32A) and if you took the cable from an HPC you could code it for 70A. Expensive approach.

On further thought if you have an HPC at home or work you could cut the cable close to the HPC, and fit a Mennekes receptacle to the HPC (turning it into a 70A single phase Mennekes EVSE) and put a Mennekes plug (plus resistor coding) on the cable. Best of both worlds. I may have to consider this option myself. Anyone got a European HPC they want to sell?

 

[doug]

Part of the RFMC (home-brew version of the UMC that predates Tesla's) construction was to get that $600 15A Tesla connector and upgrade the contacts in it for higher current, which supposedly wasn't very easy. Hence the wrinkles.

 

[felixtb]

ahh so Andrews suggestion is the better one except in Switzerland the HPCs are not legal yet...... maybe I can get one for Sweden and go from there..... have to check with one of the Nordic guys on TMC

 

[dpeilow]

On further thought if you have an HPC at home or work you could cut the cable close to the HPC, and fit a Mennekes receptacle to the HPC (turning it into a 70A single phase Mennekes EVSE) and put a Mennekes plug (plus resistor coding) on the cable. Best of both worlds. I may have to consider this option myself. Anyone got a European HPC they want to sell?

Genius

 

[Alfred]

"except in Switzerland the HPCs are not legal..." It is not a legal issue. Many local utilities do not allow to pull single phase 64A. I do know of some HPC's. One is e.g. at the Zurich store, but had to be hooked up via a large and heavy 3 to single phase transformer. Try to find a tolerant local electrician. I have heard of at least one situation where the hookup was no problem. A limitation may be that many homes are connected to the wiring in the road via 3x64A. Then using one of those phases just for your car may too much when you try to cook dinner at the same time.

 

[felixtb]

this interesting since telsa told me no not possible in Switzerland and my engineers whom are designing the epectical system for my new house said no problems I can even have max 80amp single phase! so then I guess I should tell tesla to sell me an HPC so it can be installed in my new garage. cool!

then would it not be better to cut the cable put a J1772 receptacle on the car side and the corresponding plug on the other. so then you could use J1772 EVSEs and also with J1772 <> Mennekes for Mennekes EVSEs...... . again we are really back to having J1772 on the car but with a brand new car woiding the warranty is not great in my opinion.........

 

[dpeilow]

^ Wait for the coming J1772 -> Tesla adapter cable and you have all the options then.

 

[felixtb]

ok but it seems you guys have been waiting for this cable since eternity and it certainly has not arrived yet................. do you know the ETA of this famous vaporware?

 

[dpeilow]

We've seen it being tested so it exists, but who outside of Tesla knows.