Facelift Virtual Cockpit Consumption Display

[HulkRS3]

Hi all

Have noticed there's a battery icon on the fuel consumption display via the virtual cockpit. Every so often it lights up and the consumption goes into the battery section.

What's it doing during this process?

 

[alistairm1]

Energy recuperation, as I understand it.
I think it converts potential energy available during deceleration to electricity and uses it to top up the charge in the battery.
Not sure how the technology works but someone will be along soon to explain (I hope).

 

[Tom.H]

Hi allView attachment 124376

Have noticed there's a battery icon on the fuel consumption display via the virtual cockpit. Every so often it lights up and the consumption goes into the battery section.

What's it doing during this process?

I kept meaning to look it up, I wondered what it was for as well lol

 

[HulkRS3]

Sounds about right to be honest, thought it may have been kinetic energy recuperation but instead of giving us extra power it charges the battery or something else.

 

[GSB]

Bang on the money. It is indeed an energy recovery system. Some bright spark (electrical engineer pun there - sorry) remembered his basic generator theory and all his Flemings laws, and realised that by varying the regulator output on the alternator and controlling it from the ECU you could turn off the alternator when it's not actually doing anything.

The system works like this. When you're decelerating and engine braking, the fuel supply is turned OFF and the Alternator turned up to eleven, thus getting some "free" electricity into the battery to use later. You will use this electricity later whilst cruising, so the ECU can turn down the alternator, and thus reduce fuel burn. It can periodically turn it up a bit if it senses the battery needs a bit of a top up, but as you've seen, traffic and general driving means this happens a lot anyway. When you give it the full beans, it will also turn off the alternator to direct more energy into the drivetrain.

Everyone is doing this now, but people like BMW reckon they can squeeze "up-to" 4% extra fuel efficiency with this one bit of tech alone.

 

[cemerson]

When the blurb came out about it on the PFL model, it said that the regenerative brakes were used to charge a separate battery, which was then used to reduce load on the alternator when you accelerate next.

 

[alistairm1]

GSB, cracking reply.
I've always wanted to know how it works, but all the technical info. I've found on the web was a bit too deep.
This is a great explanation, and one I have (at last) been able to grasp.

As cyclists would say "Chapeau, sir"

 

[DrMal]

Bang on the money. It is indeed an energy recovery system. Some bright spark (electrical engineer pun there - sorry) remembered his basic generator theory and all his Flemings laws, and realised that by varying the regulator output on the alternator and controlling it from the ECU you could turn off the alternator when it's not actually doing anything.

The system works like this. When you're decelerating and engine braking, the fuel supply is turned OFF and the Alternator turned up to eleven, thus getting some "free" electricity into the battery to use later. You will use this electricity later whilst cruising, so the ECU can turn down the alternator, and thus reduce fuel burn. It can periodically turn it up a bit if it senses the battery needs a bit of a top up, but as you've seen, traffic and general driving means this happens a lot anyway. When you give it the full beans, it will also turn off the alternator to direct more energy into the drivetrain.

Everyone is doing this now, but people like BMW reckon they can squeeze "up-to" 4% extra fuel efficiency with this one bit of tech alone.

Fleming's left and right hand rules. Haven't heard anyone mention them in years!

On diesel systems the interaction between powertrain and alternator is even more complex. During a DPF regeneration cycle, electrical loads will be turned-on but not shown to the driver (e.g. heated rear window) to put more load on the alternator, make the engine work harder and increase exhaust gas temperature. The engine ECU will probably also produce some "post" injection fuelling to inject straight into the exhaust gas stream. This is all designed to burn the particulate matter in the DPF.

Normally the fuel economy strategy is designed to ignore this stuff and just report fuel use related to "driving".

 

[GSB]

Fleming's left and right hand rules. Haven't heard anyone mention them in years!

On diesel systems the interaction between powertrain and alternator is even more complex. During a DPF regeneration cycle, electrical loads will be turned-on but not shown to the driver (e.g. heated rear window) to put more load on the alternator, make the engine work harder and increase exhaust gas temperature. The engine ECU will probably also produce some "post" injection fuelling to inject straight into the exhaust gas stream. This is all designed to burn the particulate matter in the DPF.

Normally the fuel economy strategy is designed to ignore this stuff and just report fuel use related to "driving".

Still use the left and right hand rules occasionally when teaching engineering graduates which way is up, just have to remember to pull on my special demonstating gloves first. They're the ones with an 'L' and an 'R' sewn on them...

With all this stuff going on in the background on modern cars, it's a wonder they work at all, never mind achieve the (frankly astonishing) levels of reliability we all take for granted. My first car had no electronics whatsoever, a simple Weber carb and a points based distributor ignition system. In comparison to my Audi it was about as complicated as a disposable barbecue, yet it would break down constantly...

 

[texbru]

Bang on the money. It is indeed an energy recovery system. Some bright spark (electrical engineer pun there - sorry) remembered his basic generator theory and all his Flemings laws, and realised that by varying the regulator output on the alternator and controlling it from the ECU you could turn off the alternator when it's not actually doing anything.

The system works like this. When you're decelerating and engine braking, the fuel supply is turned OFF and the Alternator turned up to eleven, thus getting some "free" electricity into the battery to use later. You will use this electricity later whilst cruising, so the ECU can turn down the alternator, and thus reduce fuel burn. It can periodically turn it up a bit if it senses the battery needs a bit of a top up, but as you've seen, traffic and general driving means this happens a lot anyway. When you give it the full beans, it will also turn off the alternator to direct more energy into the drivetrain.

Everyone is doing this now, but people like BMW reckon they can squeeze "up-to" 4% extra fuel efficiency with this one bit of tech alone.

Great explanation,
On my 2021 SQ7 the it never goes in to the green battery area. It stops before. Use to work great in my previous 2019 SQ5. Checked with local Audi dealer and they are working with Audi to find a fix. Audi tech acknowledged the green battery area should light up when decelerate., meaning foot of the gas pedal and just let the generator and engine slow the car down.
Anybody have ideas?
thx