← Back to context

Comment by nomel

17 days ago

How much of that performance comes for free, from optimizing for range/efficiency?

What's the obvious "that could be less" in the system that wouldn't negatively impact efficiency?

8 comments

nomel

Reply
actionfromafar  16 days ago

None of it.

It the motor is smaller, it pulls less current.

If it pull less current, you can use batteries which aren't specced for high amps.

If use use less amps, you can use thinner cabling and split the batteries up i various compartments. That means heat is more distributed. Less active cooling, if any, is needed, of both batteries and motors.

All of the above can translate to less weight, which mean better range.

  • mortos  16 days ago

    Weight has nearly no effect on range of an EV. The YouTube channel Aging Wheels has two good videos on this.

    Here he talks about towing, and he demonstrates loading the truck to max capacity makes nearly no difference: https://youtu.be/UmKf8smvGsA

    He also covered an attempted Cannonball run where they stuffed two extra battery packs into a Rivian R1T: https://youtu.be/yfgkh4Fgw98

    Real differences makers are smaller wheels and aerodynamics

    • Animats  16 days ago

      That's interesting. It demonstrates that regenerative braking really works. The energy you expend going uphill, you mostly get back going downhill. The energy you expend speeding up, you mostly get back slowing down. His tests were a round trip, so start and end altitude are the same. And he kept a fixed speed on a freeway, so there wasn't much acceleration energy expenditure or energy loss into friction brakes. You don't get drag or rolling resistance back, so that apparently dominates. Those don't vary too much with load.

      Nice result.

  • nomel  16 days ago

    > from optimizing for range/efficiency?

    I meant for normal highway driving, not drag racing.

    Optimal highway driving is still lowest resistance and losses. Cold weather driving is what mostly results in a battery capable of the high performance, from what I understand.

    Is a "small" motors more efficient than a large one? I suspect no, with the assumption that everything is sized so the "drag race" operating range would be well into the peak, rather than sustained, operating range.