Hacker News Reader

Comment by outworlder | Hacker News Reader

This is wrong. There's no warmup period.

What there is is that, if the battery is completely full, the energy has nowhere to go. So the car does not use full regen. This could be mistaken for a "warmup".

As another poster commented, this changes the accelerator feel, not the brakes.

View on HN

I disagree completely. Sure, the change in feel is related to the accelerator, but it's the slowing down of the car that changes. In a gasoline car that would be referred to as "engine braking". Imagine if in your gas car, when the tank was full, it didn't engine brake. I can imagine people getting caught off guard when the car didn't slow down like they expect.

Muscle memory is very important, and having the car behave unexpectedly is bad.

For non-Tesla cars, the effect is really minimal. As in, noone expects to actually "break" at a stop light with the regen only. Yes, I have tried, even with the Leaf's "B" mode, which increases regen.

I've heard that the Tesla's regen is so aggressive that it will even turn on the brake lights. In that case then, I agree.

Surely they'd fit a braking resistor to cover this case? Most VSDs support them so I'd be amazed if it was too much trouble to use one with a car controller.

I admit being lazy here, but I wonder what kind of resistor (and what kind of cooling) it would be needed to dump the regen braking electrical energy there instead of battery? Probably impractical...

At that point the car would just us the brakes until regen was possible.

Er, yeah there is. If you park outside for a while at low temperatures, the regen will be limited until the battery warms up.

That's interesting. I don't live in a place where the battery gets that cold (the Leaf never had to use its battery warmer), so I wouldn't know.

How low are we talking about here? I'm thinking this is nitpicking :)

Reply on news.ycombinator.com