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Use the Cruise Control on My G (TCT transmission) driving on A24/A27 and local 40mph areas, when practical.

I did notice the other day when set at 70mph and acting normally, I came to a gradual descent and before I knew it the speed had increased to 75 mph whist it was still set at the 70mph limit. Anyone else experienced this. sort of thing?

My foot is always away from the accelerator pedal when in Cruise mode.

Had to rest to correct and bring back in line.
 

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I find my left knee can occasionally hit the cruise control stalk, this sets the speed or can increase the set speed if already got a speed selected. Gradual descent shouldn't add to the speed due to engine braking.
 

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If the descent is steep, the weight and inertia of the car will often overcome engine braking, particularly when in high gear. That's why you "drop a cog" or two going down steep hills. Didn't I read somewhere that on MA engines the inlet valves stay totally shut during engine braking ? which would only serve to increase the effect....over to the experts :)
 

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I usually get excited about it. ;)

I mean you're getting all that extra speed all for zero fuel consumption!

Many Hybrids do it better though as they can store the energy using regenerative braking.
 

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Some advanced cruise control systems can apply the brakes to maintain speed on a decline. They are often an optional extra above and beyond regular cruise control but if your previous merc or jag were bought 2nd hand its possible this was fitted and you just didn't know.
 

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The radar cruise controlled ones like in my ISF can apply the brakes. Bit disconcerting at first though; you can follow a car off the motorway slowing down as it does without touching any pedals. Bit of surprise though when the car in front pulls out of the way and the ISF suddenly wants to sprint to 70 again!
 

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Some advanced cruise control systems can apply the brakes to maintain speed on a decline. They are often an optional extra above and beyond regular cruise control but if your previous merc or jag were bought 2nd hand its possible this was fitted and you just didn't know.
His jag and merc didn't have a tiny 1.4 motor and therefor had a lot more engine brake capacity.
 

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Really? How does it work, wouldn't you have some sort of massive battery to soak it all up and an electric motor to use it?
No Alfa currently has regenerative braking
 

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ALL stop start equipped vehicles have regenerative braking capability.

the stop start system keeps the battery around 85% charged, and turns the alternator to full charge under braking.
 

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ALL stop start equipped vehicles have regenerative braking capability.

the stop start system keeps the battery around 85% charged, and turns the alternator to full charge under braking.
That's not regenerative braking :lol: Just the same as any car would do.
 

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no, that's exactly what regenerative braking is.... what did you think it was?

you need a battery codition sensor and a smart alternator to do it...
Regenerative braking is when a generator connected to the wheel drive shaft recharges the traction batteries (not on an Alfa). When not braking the generator turns into an electric motor to take power from the traction batteries that have been charged via regenerative braking and help power the car. Commonly known as a hybrid car.

What your describing is just an alternator that works all the time, nothing to do with braking.
 

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no, an alternator working all the time is NOT in our giuliettas. the alternator can load anywhere from 0 to 100%, and it'll load 100% when you apply the brakes to recuperate braking energy. Same deal as a Golf, or hyundai etc...

you don't need traction batteries or an electric motor to do it, but obviously those systems are far more effective.

from wikipedia:

Regenerative brakes

Regenerative braking has a similar energy equation to the equation for the mechanical flywheel. Regenerative braking is a two-step process involving the motor/generator and the battery. The initial kinetic energy is transformed into electrical energy by the generator and is then converted into chemical energy by the battery. This process is less efficient than the flywheel. The efficiency of the generator can be represented by:

\eta_{gen}=\frac{W_{out}}{W_{in}}

Where:

W_{in} is the work into the generator.
W_{out} is the work produced by the generator.

The only work into the generator is the initial kinetic energy of the car and the only work produced by the generator is the electrical energy. Rearranging this equation to solve for the power produced by the generator gives this equation:

P_{gen}= \frac{\eta_{gen} mv^2}{2 \Delta t}

Where:

\Delta t is the amount of time the car brakes.
m is the mass of the car.
v is the initial velocity of the car just before braking.

The efficiency of the battery can be described as:

\eta_{batt}=\frac{P_{out}} {P_{in}}

Where:

P_{in}=P_{gen}
P_{out}=\frac{W_{out}}{\Delta t}

The work out of the battery represents the amount of energy produced by the regenerative brakes. This can be represented by:

W_{out}=\frac{\eta_{batt} \eta_{gen} mv^2}{2}
 

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ALL stop start equipped vehicles have regenerative braking capability.

the stop start system keeps the battery around 85% charged, and turns the alternator to full charge under braking.
That's absolutely fascinating and I had no idea.

Presumably then, if under power (fuel being used) the alternator will NOT charge the battery until it drops below 85% and even at that point will only charge progressively (say starting at just 10% but only increasing to 100% if energy capacity of battery becomes seriously low)

Whenever engine braking is encountered (defined as zero fuel usage) then the alternator always charges at 100% load unless the battery is already at 100% charge.

I'm guessing from this that it's very important to keep the AUX belt in good condition and at correct tension.

As this is such an important system (it has no negatives at all that I can see) is there some means of checking that it's working correctly ? (via MECU perhaps)
 

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you can check by oscilloscope, the rotor of the alternator will receive a PWM signal to induce the magnetic field and regulate the output.


I don't have MES yet, but it's possible you can see something there.
 

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This has got me wondering, do hybrid cars have generators on each wheel that could act as pre-brakes? I've worked on large generators where in an emergency you stop the prime mover but do not remove the excitation of the generator and the resultant power generation stops the rotor quicker. Maybe I've just described Kers? Do F1 cars use capacitors rather than batteries?
 
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