3 ms·

I was pretty impressed that my entirely gasoline-powered BMW 3-series apparently will use the braking energy to recharge the battery and disconnect the alternat

I was pretty impressed that my entirely gasoline-powered BMW 3-series apparently will use the braking energy to recharge the battery and disconnect the alternator, saving some small amount of MPG. So the technology is trickling into gasoline-powered cars as well, to save small amounts of fuel. I've driven a stick-shift for a while in the past and always wondered if there was a way to capture the engine power when you downshift for engine braking coming up to a red light. Not sure how it would work though.

sangnoir 8y ago
> I've driven a stick-shift for a while in the past and always wondered if there was a way to capture the engine power when you downshift for engine braking coming up to a red light. Not sure how it would work though. Flywheels could work, but they are heavy, and have a potentially unsafe failure mode (dense material disintegrating at high RPM).
avar 8y ago
You could integrate an alternator with the gearbox in some way, and only connect it if your foot is off the pedal, or if you're about to run out of electricity.
Shivetya 8y ago
my 2012 Z4 had limited recapture as well, it was a manual transmission with start/stop. It was there to mostly keep the battery up so you could start/stop. There was zero indication of it doing anything which I really found as a missed opportunity. You can really alter people's driving behavior if they see they are being "rewarded".
- freehunter 8y ago
  On my 2016 3 series there's an MPG bar below the speedo, and if you're in Comfort mode and coasting it will light up the battery in blue. If you're in Eco mode and braking it will flip the bar to say "charge". So I guess on newer models they took your advice and made it a bit more visible, and it definitely does impact my driving behavior because I want to see it light up blue :)

3 ms·

I was pretty impressed that my entirely gasoline-powered BMW 3-series apparently will use the braking energy to recharge the battery and disconnect the alternat

by freehunter 8y ago

sangnoir 8y ago
> I've driven a stick-shift for a while in the past and always wondered if there was a way to capture the engine power when you downshift for engine braking coming up to a red light. Not sure how it would work though. Flywheels could work, but they are heavy, and have a potentially unsafe failure mode (dense material disintegrating at high RPM).
avar 8y ago
You could integrate an alternator with the gearbox in some way, and only connect it if your foot is off the pedal, or if you're about to run out of electricity.
Shivetya 8y ago
my 2012 Z4 had limited recapture as well, it was a manual transmission with start/stop. It was there to mostly keep the battery up so you could start/stop. There was zero indication of it doing anything which I really found as a missed opportunity. You can really alter people's driving behavior if they see they are being "rewarded".
- freehunter 8y ago
  On my 2016 3 series there's an MPG bar below the speedo, and if you're in Comfort mode and coasting it will light up the battery in blue. If you're in Eco mode and braking it will flip the bar to say "charge". So I guess on newer models they took your advice and made it a bit more visible, and it definitely does impact my driving behavior because I want to see it light up blue :)