[Ladogaboy]

Someone was kind enough to point out to me that Tesla and CHAdeMO equipped cars actually use a different communication protocol than the Bolt EV (CAN bus versus IEEE.1901 respectively).

My question is, could that affect charging efficiency? I know that CAN has to run through the car's ECU, but I'm not sure whether that would add additional parasitic losses. This question is probably more loaded and involved than I think, but I thought I'd ask anyway.


*I just noticed that we actually have a dedicated "Charging" forum. Please move this post if that is more appropriate.

 

[DonC]

I thought in the US the Tesla supercharger connector was a modified version of the SAE Type 2 plug and in Europe the standard Type 2 Mennekes plug.

In any event, I can't see why a communication protocol would affect charging efficiency. It's just signaling.

 

[Dakster]

I would think it would more depend on what is or has to be powered up to accept the charge... Which is probably were Ladogaboy was going.

 

[Ladogaboy]

I would think it would more depend on what is or has to be powered up to accept the charge... Which is probably were Ladogaboy was going.

Yes, that is what I was thinking. If say a Leaf or Tesla has to power both the ECU and the BMS in order to charge, it might be significantly less efficient than if a GM vehicle could just bypass the ECU and let the charger communicate directly with the BMS.

Also, maybe some Leaf owners can confirm, but it is my understanding that very few options are available in the car while it is actively quick charging. Again, possibly an issue of relying on the CAN bus to communicate with the charger? Just trying to get a better understanding of the differences between vehicles.

 

[Dakster]

I wish I had the answer. I don't have the cars at my disposal so you could test "draw" when charging - if that is even possible in an EV/EREV. I used to test power draw when the car was off to see if I ha a phantom power draws in my cars that the batteries would seem to die quickly in. Make sure aftermarket items hooked to the accessory fuses were actually turning off, etc...

My guess is that the computers that have to run draw so little power, it probably makes a statistically insignificant amount of difference. A battery warmer/cooler turning on or HVAC pre-conditioning will of course reduce charging rate. Considering in the Volt, running the HVAC in a remote start causes a drain on the battery on 12A, L1 charger.

 

[Jeff N]

I thought in the US the Tesla supercharger connector was a modified version of the SAE Type 2 plug and in Europe the standard Type 2 Mennekes plug.

In any event, I can't see why a communication protocol would affect charging efficiency. It's just signaling.

Yes, the US Tesla plug is physically just an SAE J1772 (IEC Type 1) in that it uses the same pins with the same basic layout and pin assignments but in a different plug shape. Also, the 2 power carrying pins on the Tesla are larger because they are used for both AC and DC charging whereas the SAE plug uses a separate pair of larger DC pins for the CCS variant of the plug. Tesla also uses the same AC analog charging protocol as J1772 which sends a sine wave over the "control pilot" pin at a frequency that identifies the EVSE's maximum allowed charging current. However, Tesla and J1772 use different digital charging protocols for DC charging even though they modulate the data over the same pilot pin. Tesla uses CAN bus messaging while J1772 uses the same basic messaging protocols (IP/UDP/TCP) used by the Internet.