What's the point of KERS?

If yer a wuss!

I heard that a single amp is ample energy to kill a human. 200 amps... might feed the local crowd if you filled out your donor card.

 

Not to mention that it could certainly set off your fuel tank into a merry blaze...

 

I'am still looking I can't find it Ian... but I'am sure your right!!

 

KERS does not have anything to do with the engine operating below peak efficiency. KERS doesn't take away from engine power, it stores some otherwise wasted energy from braking.

very judgemental.

it was designed to promote passing.

 

Burning fuel isn't that nice either. There's so much electricity in the world around us, have you ever heard of someone getting electrocuted by a, whatever, fork lift? They have MUCH bigger batteries than F1 cars.

Uh. Ampere is the unit for the strength of the current, not an energy unit. What you say is like "The train was over five miles per gallon late!" -> doesn't make sense There is not one single value that determines if you get killed or not, depends on several factors like your body resistance, the path of the current (from left to right hand directly through the heart is dangerous, from one toe of one of your feet to another toe not so much), the frequency of the current etc pp.

 

IIRC, it was a pdf document explaining the qualifying rules - Two pages that went on to mention the topic at hand. You attached it to a post about quali, but a quick search didn't turn it up [You post too much! ] Oh well, thanks for looking.

Cheers,
Ian

 

@The starting issue: Michael Schumacher said on German TV that KERS can be fully loaded at the start, but is not allowed to be used under 100km/h. And he said that additional wheelspin or tire wear is NOT a problem with KERS, at least not for Ferrari.

 

Thank you Florian - You beat me to it. [Great analogy BTW!]

I bet it would make your balls ache though!......

 

The deal with the current is that like FarOut says, it doesn't take that much to stop your heart - maybe only about 150 milliamps IIRC I once read.

However, it takes whatever voltage would be needed to get through the contact resistance and to your heart to stop it. 110v AC has been proven to be plenty...

Probably more a danger to the mechanics working on it than a driver in a suit, IMHO.

I worry more about the possibility of fire - but this is largely qualified now by tank containment.

 

Oh!!!! Look who went to science camp! Yeah, yeah I didn't use the right word and I didn't know that say a foot to foot connection would be less dangerous. I guess I heard someone talking who either didn't go into much detail or didn't have a firm grasp on the topic. Thanks for the clarification, I'll be sure to rewire my dryer with my feet next time.

 

DISCLAIMER: My (pretty weak) attempt at a joke above - Current flowing from one foot to the other would be a *very* bad scenario - Florian meant from one toe to another on the same foot - Don't want anyone getting any silly ideas

It's all a question of "path of least resistance". But, it seems we're not allowed to try and explain anything here without being called out.

Oh well,
Cheers,
Ian

 

Dont see why not if the system is charged.
As per the Red Bull video it drives through the crankshaft.
That said I dont see why the engine , not only the brakes, cant charge it, like in braking zones where the engine is not under power.
Also additional "braking" via engaging a rear wheel driven generator would change the brake balance.
How can the FIA be ensured that indeed the power is being recycled through the brakes and not added by the fuel consuming engine ?

I am also assuming there is a clutch in the system to disengage the generator from the crank so as not to add additional needless rotational mass during normal acceleration.

 

Don't forget to take pictures!

... what he said. But one toe to another on the same foot would actually also be a very bad idea, before anyone really tries out. Potentially less lethal than holding the wires to your heart, but NOT something to try either.

 

The braking power is already far too much for the electric motor/generator. That's why you need normal brakes too. But even if that was different, it wouldn't work as for a combined usage of brakes and engine powering the generator, the crankshaft would have to rotate in the opposite direction than it normally does...

 

Plus the obvious fact that no matter which direction you wired the generator, it would require power from the engine and thus take away power from the wheels when you went to charge it - unless it is truly driven by the wheels during engine brake/disk brake time when the engine is cycling down.

I would hazard a guess that the actual heat/engine power of the brakes on one of these cars from the disks alone is at least an order of magnitude more than the engine can deliver...thus if you had enough battery and recovery generator you could get a lot more power than the 80 hp for 6 seconds. Remember that they can pull 4g braking down from high speed - and for sure they do not accelerate that hard - with or without the KERS.

The problem with more power from KERS is that eventually you get the KERS weighing more than the otto-cycle prime mover...wait, that's where they are on the PRIUS now, isn't it?
And, for that matter, a diesel-electric submarine...but I digress.

 

If I understood David correctly, he wanted to use the engine power during braking, when you obviously don't need it for accellerating. But, as I said, won't work if you don't add an additional generato and a clutch to seperate the wheels from the engine during braking.

4g @ 350km/h with a car mass of 750kg (correct? don't remember the exact number) equals roughly 4000hp. Only for a short moment, but if you wanted to use that kind of power fully, you'd need a ridiculously huge motor.

 

It functions as a motor/generator already. Crankshaft rotation is the same direction for both.

I'm not talking power requirements as either the engine or the "brakes" can adequately charge the batteries.
I'm talking about upsetting the brake balance with the additional drag of a generator charging the batteries instantly per the Speed TV graph. If that graph is correct.

 

Of course that graph is correct - David Hobbs said so.

 

Of course it does. But if you accellerate the engine while braking, its torque will work contrary to the braking torque and thus decrease the mechanical power available for conversion in electric energy.

I don't really understand what you mean with "upsetting the brake balance with additional drag of a generator"...? (sorry, as you might have noticed, English is not my first language )

 

Do you guys have a link to that graph?

 

He means, I think, that if the KERS generator drags down the rear wheels like additional engine braking, it might encourage the rear brakes to be more likely to lock. I would think that any team capable of F1 would have allowed for this brake balance, considering the tiny amount of torque the motor/generator puts on top of these powerful brakes.

Now, just for argument - did I also not read that you are supposed to attach the KERS thing directly to the rear wheels without a clutch? And that it is illegal to attempt to regain power anywhere else (i.e. the front wheel rotation or from brake heat?)

 

Well that's the point of KERS, decellerating the car, but not converting the kinetic energy into heat but into electric energy. If the generator didn't act as a brake, it wouldn't make any sense. And as I said: The power of the brakes is 4000hp, the generator is in the three digit range. No way anything will lock if it wouldn't do so without the generator, too.

Right. An electric motor doesn't need a gearbox, so it's directly connected to the wheels. And IIRC, only regaining power from the rear wheels is allowed. Brake heat or something like that wouldn't make sense anyway, not from a thermodynamics point of view, and much less if you had to develop a device for doing that.

 

I was kind of dreaming out loud about some specialized HFC cycle that could store the heat energy as a temperature/pressure (i.e. like steam) sort of thing and then release it into a heat engine for KERS power.

But then, I was convinced at the age of 10 that I could directly connect two DC motors together by the shaft and wire them together to create a perpetual motion machine...if only I could get them spinning fast enough.

My grandfather sat me down in the garage and explained Thermodynamics after I tried it without success until I wore myself out with it. Nicola Tesla I guess I was not.

 

Such a cycle would of course give you some power, but the exergy would be far too low to build a special system around. You'd need a turbine etc etc, wouldn't make sense.


(I actually thought of a similar device at the age of 10, although mine was a pump powered by a turbine )

 

Glad to see you guys had fun with this thread.

So here is another KERS question I can't answer:

Let's assume you're in top gear on the main straight, engine hitting the rev limiter at 18k RPM. Now you press the KERS button to get those extra 80 hp.

How does that technically work? I realize KERS has its own electric motor that connects to the drive shaft. But at the same time that shaft is attached to the engine. So does the engine rev beyond the 18k limit? Or is it electronically not possible to use KERS in that moment?

None of this stuff was answered by Matchett in RPM. Lousy job he did.