Commercial EV max speed affected by SOC of the battery ?

[Doctorbass]

I have a good question that i am probably not the only one who wonder that:

I never had any experience of driving an electric car enough time to perceive any change in speed vs the battery SOC.

Does someone know if the way they are made or programmed make them to have their max speed depending of the SOC of the battery?

I just wonder if it is or not... Or if they arrange the controller in a way that it is programmed to have a max throttle limit, let say 85% max throttle... so it leave 15% margin on the PWM so with a low battery , they it just have to modulate the max throttle limit according SOC from 85% to 100% max throttle...?

I think at a commercial point of view, they dont want that the people feel that their electric car performance decrease as the battery state of charge decrease as well... :| they probably want to give them the same comportment than gas engine car right?

Any confirmation about that ?

Luke, with the zero, wich way it is programmed?

Doc

 

[thepronghorn]

FWIW, with my family's Nissan Leaf, I do not notice any decrease in performance at low SOC's compared to high SOC's. The power is still limited to around 80 kW. I have taken it down to where it says it has 5-7 miles range and it still drove normally.

If you are actually looking for the max speed at low SOC, I have not taken the Leaf to max speed, so I have no idea.

 

[Doctorbass]

FWIW, with my family's Nissan Leaf, I do not notice any decrease in performance at low SOC's compared to high SOC's. The power is still limited to around 80 kW. I have taken it down to where it says it has 5-7 miles range and it still drove normally.

If you are actually looking for the max speed at low SOC, I have not taken the Leaf to max speed, so I have no idea.

Ok thanks, Even if you wanna try that, let me know the data.

Doc

 

[liveforphysics]

I have driven a Leaf at max speed downhill. It was either high 80s or low 90s where it hits its speed govener and wont go faster. It did this on a full pack and a low pack.

Early Zeros top speed will be directly limited by the pack voltage. 2012 BLDC Zeros use timing advance to compensate a bit, but top speed does decrease a few mph towards the bottom of the pack.

 

[Njay]

I don't know how's the LEaf power train, but in systems where the motor voltage is higher than the battery voltage (like in the prius), there's DC-DC step up converter. The converter keeps the output voltage stable at a value, even when the input voltage varies. This easily explains the steady top speed limit.

In systems where the motor is fed directly by the battery voltage, when you loose voltage, you loose top speed. Unless the controller limits the top speed to the value of a drained pack.

 

[Doctorbass]

I have driven a Leaf at max speed downhill. It was either high 80s or low 90s where it hits its speed govener and wont go faster. It did this on a full pack and a low pack.

Early Zeros top speed will be directly limited by the pack voltage. 2012 BLDC Zeros use timing advance to compensate a bit, but top speed does decrease a few mph towards the bottom of the pack.

Thanks Luke, That's interesting about the timing advance option that compensate!

Is it an option in the controller?... wich model of controller?

Doc