Battery pack and horsepower

[usmcsatcom]

I have a question about the AWD Standard Range (SR) and Extended Range (ER) battery packs and the corresponding horsepower numbers.

I understand that horsepower (HP) can be calculated by "HP = (Torque x RPM) / 5252".
Given that:
1. The vehicles are direct dive the RPM will be exactly the same and
2. The torque values are the same and
3. the time component is the same

So: (same x same) / same = a difference of 80 HP

I am missing something. What is it?

Thanks in advance.

https://en.wikipedia.org/wiki/Horsepower#Calculating_power

Apologies if this has already been asked. I did look in the search, I didn't see it.

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[Sam2084]

System power is battery limited. The SR battery puts out less power than the ER battery.

 

[BMT1071]

I have a question about the AWD Standard Range (SR) and Extended Range (ER) battery packs and the corresponding horsepower numbers.

I understand that horsepower (HP) can be calculated by "HP = (Torque x RPM) / 5252".
Given that:
1. The vehicles are direct dive the RPM will be exactly the same and
2. The torque values are the same and
3. the time component is the same

So: (same x same) / same = a difference of 80 HP

I am missing something. What is it?

Thanks in advance.

https://en.wikipedia.org/wiki/Horsepower#Calculating_power

Apologies if this has already been asked. I did look in the search, I didn't see it.

The page you linked mentions the difference between mechanical and electric horsepower. Electric motors provide virtually instantaneous torque right from 0 rpm. That's why electric cars are so much fun to drive. ?

 

[usmcsatcom]

System power is battery limited. The SR battery puts out less power than the ER battery.

Thank you for your reply.

My question then becomes: With less power how are the torque numbers the same?

I am new to EVs but typical electric motors pull the most current when starting from a stand still. Starting from stopped is where I assume the advertised torque numbers are generated, since "off the line torque" is what people care most about.

Perhaps they measure torque in some other regime? If measured off the line then peak draw occurs simultaneously with advertised torque and both batteries would have to supply the same current.

Perhaps off the line the torque/current is the same, but then the different configurations follow some sort of programmed power curve? This would have to be a software limitation since the battery is capable of providing the current. At least for a short period.

I guess it is a bit more complicated with EVs than ICE. Does anyone know a good resource for this type of information?

 

[hybrid2bev]

Thank you for your reply.

My question then becomes: With less power how are the torque numbers the same?

I am new to EVs but typical electric motors pull the most current when starting from a stand still. Starting from stopped is where I assume the advertised torque numbers are generated, since "off the line torque" is what people care most about.

Perhaps they measure torque in some other regime? If measured off the line then peak draw occurs simultaneously with advertised torque and both batteries would have to supply the same current.

Perhaps off the line the torque/current is the same, but then the different configurations follow some sort of programmed power curve? This would have to be a software limitation since the battery is capable of providing the current. At least for a short period.

I guess it is a bit more complicated with EVs than ICE. Does anyone know a good resource for this type of information?

See if this thread helps any.

https://www.macheforum.com/site/thr...insteed-of-the-rwd-sr-version.2755/post-86471

 

[usmcsatcom]

See if this thread helps any.

https://www.macheforum.com/site/thr...insteed-of-the-rwd-sr-version.2755/post-86471

That is great! Thank you!

 

[ChasingCoral]

As stated above, it is based on both the motor and the power delivery of the electrical system. See the spec sheet.

 

[SnBGC]

I have a question about the AWD Standard Range (SR) and Extended Range (ER) battery packs and the corresponding horsepower numbers.

I understand that horsepower (HP) can be calculated by "HP = (Torque x RPM) / 5252".
Given that:
1. The vehicles are direct dive the RPM will be exactly the same and
2. The torque values are the same and
3. the time component is the same

So: (same x same) / same = a difference of 80 HP

I am missing something. What is it?

Thanks in advance.

https://en.wikipedia.org/wiki/Horsepower#Calculating_power

Apologies if this has already been asked. I did look in the search, I didn't see it.

Time is not the same.

 

[SnBGC]

Thank you for your reply.

My question then becomes: With less power how are the torque numbers the same?

I am new to EVs but typical electric motors pull the most current when starting from a stand still. Starting from stopped is where I assume the advertised torque numbers are generated, since "off the line torque" is what people care most about.

Perhaps they measure torque in some other regime? If measured off the line then peak draw occurs simultaneously with advertised torque and both batteries would have to supply the same current.

Perhaps off the line the torque/current is the same, but then the different configurations follow some sort of programmed power curve? This would have to be a software limitation since the battery is capable of providing the current. At least for a short period.

I guess it is a bit more complicated with EVs than ICE. Does anyone know a good resource for this type of information?

All very good questions.

The torque is measured the same. Also measured throughout the RPM range, not just off the line.
The electric motors in both vehicls have the same torque rating because the two battery types have the same basic voltage reading.

HP is work, or force x time, or torque times time....which leads to the equation you referenced earlier.

The larger battery can discharge more watts compared to the smaller battery. So, even though the voltage is the same (also means the torque is the same)......the watts are greater when coming from the larger battery. So, the more watts, the faster the motor will spin. (RPM)

So, if both vehicles are at a dead stop, and both apply maximum power to the motor for a set length of time (10 seconds, 60 seconds etc). Then the vehicle that delivers more watts to the motors will cause the motors to rotate more often in that amount of time. Since we are talking about RPM.......then M is 1 minutes (60 seconds). In that 60 second time frame, the motors in the vehicle with the larger battery will rotate more times compared to the motor in the vehicle with the smaller battery. This means the tires will rotate more times in the larger battery vehicle compared to the smaller battery vehicle. If the tires rotate more times in that 60 seconds, then it will travel further (assuming no wheel slip). Traveling further in the same amount of time is more work which is more HP.

Lastly, if you travel further in the same amount of time then you are also traveling quicker which is what we commonly associate with higher HP figures.

Hope this helps clear it up.
I agree it is a bit strange but accurate in now they rate the HP figures. ?

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