McLaren 25kg KERS unit

[Conceptual]

So, McLaren have a 25kg KERS unit that is featured on the front page of this site.

My question however, is since the teams all run an alternator already, wouldn't an integrated MGU/alternator have been the most obvious way to do this?

I may not have an engineering degree, but I do believe that combining these units should be possible.

Can anyone give an educated guess why they were not condensed for more weight savings?

Thanks!

[WhiteBlue]

I do not know what you mean by this. Merc use an integrated Motor/Generator unit they explain in the video, that sits at the traditional place behind the gear box. The other two units are the power control electronics (basically an inverter) and the batteries. These two units sit in the left and right side pot respectively. One particular design feature of the McMerc Kers battery is the flat design which leads to a very low CoG.

[Giblet]

My guess is the alternator is likely so well integrated with the engine they would have to redesign their 'sealed' engines.

The fact that KERS is still experimental to a point has helped at least Ferrari to finish races. If KERS was also the alternator, and KERS needed to be turned off, the day is over.

[RacingManiac]

FYI, its not unusual for alternator NOT being driven off the engine directly on race cars. Some are even driven off the half-shaft. I really don't see why it can't work in that fashion in some part of the drivetrain while working as a motor assist unit. Though I don't doubt some pretty major redesign might be needed to the electrical system to handle this.

Lola's LMP car have long had starter-nator, which in early days have been problematic but the feature certainly have survived since its use in 2001. That basically means you can already use the alternator in their case to actually crank the motor for starting...

[Giblet]

Oh yeah...

There was a driver in (I think) the Indy 500 who (I think) was Dan Gurney, and he ran out of gas and came to a stop shortly before the finish line, but used "electric power" to cross the line, finishing (winning?) the race.

I read this in a magazine many years ago, and don't remember the details, but I do remember that a gas driven car was able to cross the line under electric power, which I found odd, because I thought cars of that vintage also needed external starter motors to fire up.

[Conceptual]

As far as my research into alternators go, it should just be a trick to the winding to integrate an Alternator/MGU. The size may become a bit larger, but you would think that putting both units into one single case would save some weight, and not interfere too much with the engine packaging.

But, as xpensive says, since I am not an engineer, I shouldn't have these ideas unless I know the numbers behind them!

[pipex]

Excuse my ignorance but F1 cars have alternators? i knew that they have a small battery for all the electronics, but i don't know about an alternator ???

[Giblet]

A battery can not hold a charge long enough to maintain a spark to completely burn fuel up to 18,000 times every minute, that can fit in a car.

[pipex]

Yup, thanks Giblet
I found that they indeed have one http://www.denso.com.au/news_releases/2 ... tor_for_f1
I should have searched before asking...

[pipex]

I think that integrating the two systems would be a nightmare. The voltage levels of the two systems are too different, and the requirement in terms of currents too. I have too little information about the electric system of F1 cars, but mixing these two systems without any sort of insulation between them doesn't look nice to me.
What can be done i think is using the same battery for the two systems, but that is where the problems begin to appear. You need to be charging the system in a constant way and maintain the capabilities of the battery for the KERS system. I don't know if this is compatible with the rules.

[Henning]

The most amazing thing I found out in the article about McLaren's KERS unit is that it takes 0.5 seconds to fully charge under braking. This could mean that the power output or duration could be increased very easily by charging more than once per lap.

[DaveKillens]

Mclaren are to be congratulated for their system. It seems mature and reliable, something the others appear to have difficulty with.
The timing of this release of information by McLaren is funny. I comes out when other teams are crying for it to be abolished. Personally, I believe McLaren want KERS to survive, if only for the simple fact they have a working system. And if next year KERS becomes a standardized component like the ECU, then McLaren have an inside track on securing that contract.

[Belatti]

The most amazing thing I found out in the article about McLaren's KERS unit is that it takes 0.5 seconds to fully charge under braking. This could mean that the power output or duration could be increased very easily by charging more than once per lap.

The same thought.

Lets watch a little to the braking analysis our friend bar555 did in another thread:

Kurve 1
Initial speed 2009 : 301 Km/h
Initial speed 2008 : 309 Km/h
Difference : - 8 Km/h
Final speed 2009: 165 Km/h
Final speed 2008: 151 Km/h
Difference : + 14 km/h
Stopping distance 2009 : 77 m
Stopping distance 2008: 102 m
Difference : - 25 m
Braking time 2009 : 1.28 seconds
Braking time 2008: 1.7 seconds
Difference : - 0.42 seconds
Maximum deceleration 2009 : 5,32 g
Maximum deceleration 2008 : 4.5 g
Difference : + 0.8 g
Maximum pedal load 2009 : 140 Kg
Maximum pedal load 2008 : 131 Kg
Difference : + 9 kg


Kurve 3
Initial speed 2009 : 286 Km/h
Initial speed 2008: 290 Km/h
Difference : - 4 km/h
Final speed 2009 : 143 Km/h
Final speed 2008 : 139 Km/h
Difference : + 4 km/h
Stopping distance 2009 : 81 m
Stopping distance 2008: 91 m
Difference : - 10 m
Braking time 2009 : 1.47 seconds
Braking time 2008: 1.6 seconds
Difference : - 0.13 seconds
Maximum deceleration 2009 : 4.87 g
Maximum deceleration 2008: 4.0 g
Difference : + 0.87 g
Maximum pedal load 2009 : 128 Kg
Maximum pedal load 2008 : 123 Kg
Difference : + 5 kg


Kurve 4
Initial speed 2009 : 288 Km/h
Initial speed 2008 : 287 Km/h
Difference : + 1 km/h
Final speed 2009 : 113 Km/h
Final speed 2008 : 120 Km/h
Difference : - 7 km/h
Stopping distance 2009 : 96 m
Stopping distance 2008 : 93 m
Difference : + 3 m
Braking time 2009 : 1.93 seconds
Braking time 2008 : 1.8 seconds
Difference : + 0.13 seconds
Maximum deceleration 2009 : 4.85 g
Maximum deceleration 2008 : 4.6 g
Difference : + 0.25 g
Maximum pedal load 2009 : 128 Kg
Maximum pedal load 2008 : 146 Kg
Difference : - 18 kg


Kurve 6
Initial speed 2009 : 297 Km/h
Initial speed 2008 : 301 Km/h
Difference : - 4 km/h
Final speed 2009 : 149 Km/h
Final speed 2008 : 148 Km/h
Difference : + 1 km/h
Stopping distance 2009 : 83 m
Stopping distance 2008 : 90 m
Difference : - 7 m
Braking time 2009 : 1.45 seconds
Braking time 2008 : 1.5 seconds
Difference : - 0.5 seconds
Maximum deceleration 2009 : 5.19 g
Maximum deceleration 2008 : 4.7 g
Difference : + 0.49 g
Maximum pedal load 2009: 137 Kg
Maximum pedal load 2008 : 149 Kg
Difference : - 12 kg

That is a total of 6.13 seconds of braking. And we are still missing Kurve 2, 5, 7 and 8.

If they use 80HP for 6.7 seconds that recharge in 0.5 seconds of braking, that means they could use the 80HP for over 81 seconds. Those 81 seconds plus the 6.7 seconds spent in braking equals to the lap time.

So basically, this KERS is that good enough you can have a +80HP car with "only" 25Kg more?

I LIKE THIS KERS

Regarding the counterpart "movable ballast" that Norbert talked about, what if they change the position of the battery and control unit? Wouldnt that be "movable ballast" to play with?

[Project Four]

The KERS MGU (Motor Generator Unit) is a combined generator and a motor and being linked directly to the crankshaft of the engine can take power from the engine to charge the batteries (generator) and then deliver additional power back to the engine from the batteries (motor). While, the alternator is used to supply power to all of the electrical devices on the car.

If the KERS MGU and alternator was combined together, which from a voltage / current generation perspective would be possible. During the motive phase of the KERS cycle I can’t see where electrical energy would come from to power the rest of the car, unless this could also come from the KERS batteries.


On the BBC website : -
http://news.bbc.co.uk/sport1/hi/motorsp ... 019577.stm

is a similar video to the German video explaining the Mercedes KERS system.

[Conceptual]

What I am saying is that even if they were side by side, the MGU and alternator should be able to use a commom axle. An alternator is in fact a generator, and a generator is in fact a motor, so on that basis they should be able to be integrated into a single unit.

If the windings were done so the 12VDC alternator was always running (even under KERS boosting) there would be no loss to the Alternator system.

The only single point failure that I can forsee is if the KERS unit ONLY SPINS when charging/discharging. If that is the case, then it would NOT be integratable.

Scarbs, if you are out there, doe you have any information about this? Have any teams integrated their KERS MGU with their alternator?

PS: that 25kg KERS unit of McLaren and its charging times are amazing. I wonder if they would be willing to release the MAXIMIM performance numbers? I mean, we all know the 80hp/6.67s boost limits, but if KERS were unrestricted, what would that same unit be able to produce? I mean, if we are talking 200HP over the entire lap, then moving to I4 turbos (600hp) would still give us some amazing racing!