5 ms·
I'm surprised. I haven't studied this in detail, of course, but regen braking seems to work fine on my Leaf. There is a(n annoyingly) noticeable transition from
by goodcanadian 6y ago
I'm surprised. I haven't studied this in detail, of course, but regen braking seems to work fine on my Leaf. There is a(n annoyingly) noticeable transition from regen to mechanical braking. The vast majority of the time, it is using regen.
- mikepurvis 6y agoYou may be getting stopping power, but the issue is whether you're stopping gradually enough for a meaningful amount of that power to actually be captured in the battery vs. dumped to the environment as heat. I notice this on my electric longboard as well— longer, more gradual brake actions are way, way better for range than stopping more aggressively. I think to get the power from more sudden stops, you'd need to have some kind of intermediate storage (like a capacitor bank) that could hold that energy for 20-30 seconds while it's streamed at the appropriate rate back into the main battery.
- skykooler 6y agoI've seen a few homemade electric cars from around fifteen years ago that combined batteries with a bank of ultracapacitors for exactly that purpose.
- mikepurvis 6y agoThat's neat— I wonder if the gains are simply too small for it to make sense in a mass-market vehicle. Either way, seems like it would be a slam dunk for a delivery truck, city bus, garbage truck, basically any heavy vehicle with a stop-start workflow.
- skykooler 6y agoI think it's more that the capacitors are too expensive for mass production - the figures I saw put them at around $10K, for something that contributes a relatively small amount to the performance of the vehicle. Manufacturers would probably prefer to put that towards a bigger battery pack, which would give better overall specs, if a bit less efficiency.
- BlackNitrogen 6y agoYou don't need ultracapacitors, regular ordinary teslas starting with the 2012 model S have had this. It's not quite a decade old.
- mikepurvis 6y agoDo you have a source on that? This article, for example, on the Tesla website is clearly aimed at a lay audience, but nonetheless mentions nothing about an intermediate capacitor bank for absorbing spikes of regen braking energy: https://www.tesla.com/en_CA/blog/magic-tesla-roadster-regenerative-braking https://www.tesla.com/en_CA/blog/magic-tesla-roadster-regene...
- BlackNitrogen 6y agoI don't get your question. But that is a roadster, not an S or later. But it presumably doesn't mention intermediate capacitors because they don't use them.
- skykooler 6y agoI think you and mikepurvis are both saying the same thing - that Tesla and other electric cars are using batteries only, not capacitors. I will note that the homebuilt electric cars generally had much smaller battery packs, which could not supply the same peak currents that a 50+kWh battery would have.
- goodcanadian 6y agoSudden stops are not the majority of my stops nor do I suspect that is the case with delivery trucks. In sudden stops, I care more about immediate safety and less about energy recovery, anyway. I would be very surprised if the battery is not soaking up most of the energy under normal conditions.
- hyperbovine 6y agoHow much kinetic energy is your Leaf dissipating compared to a loaded delivery truck?
- hedora 6y agoThe energy is roughly proportional to weight, as I imagine the electric motor and battery amperage are.