Recuperative Braking

[Timothy Nathan]

What does it actually mean? I mean what is the actual practice on VAGs?

Does it mean that if you always brake gently you will never let the pads touch the discs, or does it mean that a tiny amount of the initial braking force is inductive and that really the brakes are getting hot just like in any other car?

[shabazmo]

I thought it mean't that the alternator saps more power by the engine to charge the battery. In doing so it causes a braking force on the engine at a time you want the car to slow down. i.e. the braking only occurs when your foot is off the pedal. I must admit I have never felt it workin, so interested to hear views of others.

[Timothy Nathan]

Actually, it does make sense, I do have the feeling that the car slows down faster when you take your foot off the throttle than in other cars - I had attributed that to the gearbox.

[BigAid]

When you’re coasting or braking, the car’s alternator generates energy. Brake energy recuperation allows this energy to be stored. When you accelerate or drive at a constant speed this stored energy is used so less energy is wasted in driving the alternator. This lowers fuel consumption and CO2 emissions.

http://www.audi.co.uk/audi-innovation/efficiency.html

with a naf video of spinning coins - interesting words though - seems to be F1 KERS style system.

[nealeb]

Only difference from KERS is that the stored energy is not used to give additional acceleration but there is something satisfying about using otherwise-wasted braking energy to charge the battery and that is then used for things like the air conditioning. Given that any car these days should have some kind of smart alternator regulator to look after the battery properly it's not that difficult to add the recuperative braking thing. What I am not sure about is how the car makes sure that the battery is properly charged; on a long motorway journey you might hardly ever need to touch the brakes! I think that it's unlikely that you would notice the effect in practice, though - assuming, say, a 20A charge current, that's only the difference of 1/3HP one way or the other. But as far as fuel saving is concerned, every little helps!

I presume that everyone has seen the bar-graph fuel consumption display on the DIS? That has a small green "and now I'm charging the battery" section at the end of the display that lights up when fuel consumption is zero - translates to overrun conditions, generally. Or is it just the sad old geek community that actually looks at fuel consumption anyway?

[Timothy Nathan]

I have that as my standard setting on the DIS (but then, as I have HUD, all the primary information is on that anyway.) We can be sad old geeks together.