Are people ordering the second 10KW charger?

[bluetinc]

This does not sound right at all.

The plus 15 shown is the number of miles that have been added to the range on the charge so far, and doesn't have anything to do with a bonus for the chargers. I don't believe that there is a difference in charge rates on the car when charging at 40A 240V (or less) between a single charger and dual chargers.

As I've had a lot of time and opportunity to play with charging at various currents and voltages using either a single or dual chargers and listening to the relays while watching the current draw, here is what I see:

Charging sequence starts up and if the current is set to 40A or less then only one charger is used, and current ramps up. If the current is above 40A, relays are switched, and then charging current ramps up to the requested rate.


Peter

Looks like there is one more reason for the second charger!

Cross post from:http://www.teslamotorsclub.com/showthread.php/10398-Model-S-Technical-Mechanical-Issues/page104

 

[smorgasbord]

From what I heard from the Tesla Service guys is, that the cars with a single charger charge a lot slower even at 240/30A than the ones equipped with dual chargers. With two, they balance the load in a master-slave-configuration. Cars with one charger take between 20 and 40% longer on very same NEMA 14-50 outlet.

This doesn't sound right to me. Anyone got a second confirmation, or a name of someone in the know?

 

[rcc]

That makes very little sense to me. I'm seeing 39-40 Amps at close to 240 volts when charging on a 14-50 outlet. It's hard to imagine how a dual charger could make that better given that the outlet and circuit are about maxed out.

 

[cinergi]

From what I heard from the Tesla Service guys is, that the cars with a single charger charge a lot slower even at 240/30A than the ones equipped with dual chargers. With two, they balance the load in a master-slave-configuration. Cars with one charger take between 20 and 40% longer on very same NEMA 14-50 outlet.

I don't believe that for one second.

- - - Updated - - -

Looks like there is one more reason for the second charger!

Cross post from:http://www.teslamotorsclub.com/showthread.php/10398-Model-S-Technical-Mechanical-Issues/page104

As I posted over there, that's also false. The +15 refers to mileage added since the charging session started. It has nothing to do with additional charging power.

 

[gregincal]

I'm still thinking that if one assumes that people will keep installing public chargers in the future that a lot of them will be DC fast chargers. In the US they'll likely have both CHAdeMO and SAE dual plugs for awhile. As cars go to bigger batteries, I think there's going to be a lot more interest in much faster charging than 240V @ 70A. As the market for DC chargers grows they should get cheaper, and a lot of the cost of installing a charge point isn't dependent on the charge rate anyway.

I also agree with this. While dual chargers might be useful future proofing for one possible future scenario, DC charging is definitely where things will end up. I'm not sure high current AC will ever get much penetration, but who knows. Yes an extra 60 miles in an hour is better than 30 miles in a hour, but not by much. Neither is practical unless that is all the extra range you need.

 

[lolachampcar]

One caveat is that "high current AC" exists everywhere while DC requires additional equipment. I have not gone looking for it but I suspect there are not a lot of greater than 50 amp single phase NEMA plug/socket combos around which drives the need for an installed box. Perhaps someone with more knowledge can chime in here.

The reason the HPWC is needed over the mobile charge cable is to force a hard wired connection for the greater than 50 amp service (and larger wire diameter for the extra current). The signaling to the car is different to tell it there is 80 amps available. See J1772 here http://code.google.com/p/open-evse/wiki/J1772Basics . This specification allows the box on the wall to change the available current indication to the EV so that the EV can adjust its consumption. It is possible to do things like charge at a low rate until your rates fall at a certain time then jump up to a higher rate. Alternatively, if you have limited service, it would be possible for the wall box to monitor overall current usage (in your house) then adjust available current to the car accordingly so you use all available service to the the house.

You could set the dip switches in the HPWC to 40 amp service and it would look just like the mobile cable to the car.