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Daox -

Originally Posted by Daox

This was interesting to see. Its similar to what a few mfgs are doing by fully powering up the alternator during braking, but they're using capacitors to be able to capture more energy. They're also bumping up the alternator output voltage to capture more energy as well (variable from 12-25V). They claim a max FE increase of 10% which is what we've seen be eliminating the alternator here on EM.

Mazda Improves Fuel-Saving Start-Stop System With Capacitors

Oooooooh, ultracaps in a big automaker drivetrain :

Unlike batteries, which are very limited in how rapidly they can charge, or discharge, due to heat and chemistry constraints, capacitors can very rapidly store and discharge energy. The capacitor in Mazda’s system, the automaker says, can be fully charged in seconds. Other strengths of capacitors is that they’re easier to package, and they don’t deteriorate appreciably over time, as batteries do.

...

Capacitors have been examined for more than a decade as an energy-storage alternative to batteries, but the downfall of capacitors—or larger-scale ultracapacitors—is that they’re essentially one-trick ponies, with discharge rates that can’t be significantly extended. Many automakers are examining them as buffers to help increase efficiency in hybrids, and some have used them with fuel-cell vehicles—in earlier development versions of the Honda FCX fuel-cell vehicle, for example.

Mazda’s configuration makes sense for congested city-driving patterns, where rapid braking is typically followed by idling; and it’s in those following seconds that ancillaries can best use the extra power.

CarloSW2