# KERS - the future of antilag?



## kismetcapitan (Nov 25, 2005)

kinetic energy regeneration systems are being used on this year's F1 cars. for 25kg extra weight, a flywheel energy storage unit can supply six seconds of 60kW of electric-assist. Not only is that an 80hp boost, it's from an electric motor, which means instant torque.

it has just occurred to me that such a boost from an instant torque electric motor could also assist in spooling up an engine. Six seconds is plenty to boost an RB26 until the turbos come online.

I guess the most similar effect would come from nitrous (an 80-shot would be about what you'd get from a single fogger programmed to aid in spoolup, give or take some), but a KERS system would, for not that much more weight, never require tank refills.

F1 reports that the 60kW motor weighs only 8kg...? I wonder if that could also serve as the starter motor? (I actually don't know where the starter motor is on an RB26, surprisingly enough!)

thoughts? I definitely plan to, in some distant (or not-so distant?) future, to convert my car to full electric with 100~150kW motors per wheel. Just requires several generations of battery development...


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## Sub Boy (Jan 28, 2008)

The starter motor sits to the side of the engine and drives straight onto the flywheel.
They probably could be made on in the same....Crap only knows how the whole system works though....

....And only one team in F1 at the last race was using it, Doesn't look like a good future for it!


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## kismetcapitan (Nov 25, 2005)

the technology is immature, and the nasty electrical shock the BMW Sauber mechanic took didn't help with people's faith in it! Bosch is developing a KERS system that will likely see use in hybrid cars within a couple years.

The system is actually fairly simple. you've got the electric motor, the flywheel storage device, and a battery. Under energy regeneration, power is taken off the drivetrain to spin the flywheel. The flywheel spins in a vacuum suspended on magnetic bearings. Then when you hit a button, power is taken from the flywheel, goes to the battery (or supercapacitor), then runs the electric motor. You could just have the motor and battery, and run the electric motor backwards to charge, but flywheel energy storage has the advantage of a fast "charge" (no chemical reaction to induce as in a battery, you just need to spin up the flywheel to max rpm) and weighs less than an equivalent battery.

F1 rules limit the time to six seconds and the motor's power, but in an aftermarket application the power could be bumped up to 80kW or so. Hybrid technology used in a not-so-green application


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## kismetcapitan (Nov 25, 2005)

this, btw, has made me wonder why starter motors have been used in double duty as alternators as well? It'd just take some simple electrical switching - discharge on startup, then without disengaging the motor pinion gear, switch to generation. It doesn't necessarily save anything in terms of parasitic loss, but it sure does simplify things by taking one unit out of the accessory belt drives and saves a bit of weight as well. Since it hasn't been done...there must be a good reason why?


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## NISFAN (Oct 11, 2003)

Perhaps because a starter motor spins the engine at aprox. 200rpm during cranking. Don't expect it will last long at 9000rpm, lol - - - Obviously a differential gearing system would need to be employed. 

Years ago, cars used to use a device called a generator, which looked just like a starter motor. However the alternator became the chosen device because it was far superior in terms of output and efficiency.


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## mattysupra (Oct 31, 2008)

kismetcapitan said:


> I actually don't know where the starter motor is on an RB26, surprisingly enough!)
> 
> ...


WHAT? your pulling me 3rd leg ent you? 

You of all people dont know where the starter is, i ent being funny mate but i have read alot of your threads and bright ideas and agree with alot of your daft ideas.

However the power steering thing was a bit ,.......

You map your own car too dont you? I recall something about knock problems and reading the knock etc that you seem or 'seemed' to understand etc, and then you admit you dont know where the starter is! PMSL!


I dont belive you own a skyline after reading that mate, post a pic of yourself doing something daft on the front of your car to prove your not pulling my leg! (keep your clothes on please):runaway:


Please tell me your pulling my leg! LOL.


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## mattysupra (Oct 31, 2008)

o and to answer your post. The Kers system weight is more than 20k is it not? That seems very light for the amount of time it costs the cars on a lap when not using it. 

I like your theory tho. but i think the weight out ways the power increase does it not? However 80bhp to get the turbos online should do the trick in theory. 

You have me thinking tho and as it happens my mate works for Mclaren F1 doing ..... (cant tell you) but i will show him this thread at the weekend when i see him next !


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## NISFAN (Oct 11, 2003)

mattysupra said:


> o and to answer your post. The Kers system weight is more than 20k is it not? That seems very light for the amount of time it costs the cars on a lap when not using it.


F1 cars using KERS weigh exactly the same as those without. However the non KERS cars use ballast weights to modify the CG, as well as get the car up to the minimum weight, KERS cars don't have as much freedom in that dept.

Think only Toyota use the flywheel system, but I thought it transferred it's kinetic energy directly onto the crank via a clutch. The others, use a pure battery and charger system. 

Lewis didn't use KERs at Silverstone, and got out qualified by his team mate who did use it.:thumbsup:


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## mattysupra (Oct 31, 2008)

NISFAN said:


> F1 cars using KERS weigh exactly the same as those without. However the non KERS cars use ballast weights to modify the CG, as well as get the car up to the minimum weight, KERS cars don't have as much freedom in that dept.
> 
> Think only Toyota use the flywheel system, but I thought it transferred it's kinetic energy directly onto the crank via a clutch. The others, use a pure battery and charger system.
> 
> Lewis didn't use KERs at Silverstone, and got out qualified by his team mate who did use it.:thumbsup:


i was under the impression that the cars was lugging more weight when running KERS? so its down to ballast in other cars and them being able to move the ballast to where they wont then? Surely the kers cars could move something else to ballast out then? 

O and what the hell has happened to lewis? How can they get the car so wrong when it worked so well last year? I know at silverstone he got mugged of a good time at the qualifing but he admited himself that he could not go any faster with that car. So if no KERS, whats going on?


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## NISFAN (Oct 11, 2003)

Well McLaren don't have a weight issue, atleast. 

I know some of the heavier drivers don't use KERs (Kubica???) because the car is close to the limit, and would actually weigh more if KERS was fitted, so would be a severe disadvantage.

Yes tell me about Lewis, McLaren has gone from one of the best to absolutely the worst car out there. Even Force India's are faster, lol, and we know it is not the engine. Lewis wanted to try the car without KERS to see if he could set it up better. Also didn't use it in Monaco, but that track is not KERS friendly anyway.


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## bigmikespec (Sep 5, 2008)

Something that is related to what you mentioned (KERS) is what some turbocharger manufacturers are looking at and that is driving the turbocharger shaft via electric motor to increase spool from low throttle...

Browser Warning

Sorry, it has been mentioned before?


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## kismetcapitan (Nov 25, 2005)

mattysupra said:


> WHAT? your pulling me 3rd leg ent you?
> 
> You of all people dont know where the starter is, i ent being funny mate but i have read alot of your threads and bright ideas and agree with alot of your daft ideas.
> 
> ...


the fact is, I never thought about the starter motor, never bothered to look for it on the car, and never realized that I had been ignoring it until just recently! It's obviously near the flywheel, I'll go have a look just so that I can fill this glaring hole in my knowledge base...I've been hands-on through four rebuilds, have self-installed a lot of ancillary systems, do my own mapping...but yep, have never seen the starter motor on the engine! (I probably _have_ seen it, but just didn't process the information as I was likely looking at something else)


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## NISFAN (Oct 11, 2003)

Never mind looking at the starter motor, try removing it and re-fitting. 

You can't claim to have worked on Skylines without losing 2 pints of blood, 25cm^2 of skin and fracturing atleast 4 bones in your arms and hands whilst trying to contort your body, and then your arm into the right position to get at the thing.

P'ah, four re-builds


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## Pete G (Aug 18, 2008)

NISFAN said:


> Perhaps because a starter motor spins the engine at aprox. 200rpm during cranking. Don't expect it will last long at 9000rpm, lol - - - Obviously a differential gearing system would need to be employed.
> 
> Years ago, cars used to use a device called a generator, which looked just like a starter motor. However the alternator became the chosen device because it was far superior in terms of output and efficiency.


It's only turning slowly because it is designed for low speed high torque to crank the engine using battery power,- the bearings could be replaced with high speed ones I would think?.
The other point is that it is a DC motor like the dynamo (generator) in my old car which are basically the same thing,- spin them and they produce electric power, apply electric power and they spin. Alternators produce AC which has to be rectified to DC to keep the battery charged and run everything.


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## kismetcapitan (Nov 25, 2005)

current hybrids use the electric motor as a starter motor, so they've clearly sorted out whatever issue they were having.

Why (there must be a good reason) would an alternator produce AC which has to be converted to DC, when a dynamo could just produce DC from the start? Maybe for voltage regulation? (an alternator without a regulator would produce too much juice at high RPM - it makes peak power usually around 3000rpm, that much I know)


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## NISFAN (Oct 11, 2003)

I'm thinking generators produce a linear but constant power supply dependant on revs. This means if sized for average engine speed, they don't produce enough power at low revs to re-charge batteries, etc. Also the output cannot be adjusterd at times when you don't need the power.

Whereas an alternator has got 'need' control, and also has the capability to produce enough power at low revs to charge things.

So for example, an alternator can use a lot of (engine) power if you had the aircon, lights, wipers, etc on because there is a lot of power drain going on. But on low load situations it self adjusts to not require the same engine power. The perfect device.

Generators require a certain amount of power to drive them regardless of load on the electrical system. To have a generator large enough to cope with a 'modern' car, it would be a huge device, much bigger than a starter motor.

Recently, intelligent alternator control devices have appeared, whereby the alternator is fooled into working really hard during engine overrun, which in turn means it uses 'engine braking' energy rather than 'engine power' to drive it. Most new BMW's etc use this technology now for fuel saving.


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## ru' (Feb 18, 2007)

The car industry is moving towards (or trying to) having a single starter motor/generator device (as well as using higher voltage than 12V, say 40V ish). This will enable basic regeneration power systems.


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## minos (Sep 21, 2006)

well i don't think it will be long before cars don't come with starter motors at all, i know some of the "i stop" techonolgy is relying on starting the engine, by making sure the car know where the piston is located and then start a combustion on a piston that is traveling down, will be a shitty combustion but enough to get the engine moving

as for now it still engages the stater driver but, car starts in less than 0.3sec (at least on the new mazda3, i guess with some more R&D, they will be able to ditch the starter


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## kismetcapitan (Nov 25, 2005)

NISFAN said:


> Recently, intelligent alternator control devices have appeared, whereby the alternator is fooled into working really hard during engine overrun, which in turn means it uses 'engine braking' energy rather than 'engine power' to drive it. Most new BMW's etc use this technology now for fuel saving.


I want that!!! The ultimate alternator upgrade!!


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## NISFAN (Oct 11, 2003)

Hmmmm, you've got me thinking that I want that too now  

I have an aftermarket ECU that would be capable of turning the alternator 'off' under load. Not sure I would want to do that at high RPM, as I want all the power needed to fire the plugs.............
............. but perhaps to aid anti lag, I could turn it off at high throttle openings at low to mid revs. This will give the engine a couple of extra horses to get through the laggy phase.

I don't think it would be that difficult to set up another circuit that makes the alternator engine brake, overcharge either. Could do this by simple brake light activation, or perhaps via the ECU (road speed above xxx, and throttle position below yyy)

Cool thanks for the idea Kismet


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## kismetcapitan (Nov 25, 2005)

dude, let's engineer this thing together. The stock alternator is 85 amps, I've got a 160 amp Infiniti alternator on the car now, and I would like to go up to a 200 amp unit.

My one concern is the ignition system. Mine seems to hate low voltage conditions and will stutter and stall if the battery is low (Splitfires + HKS DLI + NGK surface-gap plugs which require a lot of juice). During hard acceleration, my car seems to use a lot of electricity through the ignition - after a spirited romp, the battery and the car's system voltage is lower, similar to if I've been sitting in traffic with the A/C and my 800 watt stereo cranked up.

What ECU are you running? I've got a simple Power FC - I'm trying to remember if any of those wire terminals on the Datalogit box are programmable outputs?


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## kismetcapitan (Nov 25, 2005)

oh, and a question about alternators. There's no clutch; the internal rotor is always spinning as far as I know. Is it when the regulator switches on, that resistance is created and a load placed on the engine? Just how many horsepower does an 80 amp alternator sap out of the engine? a 160 amp? I think I better hit Google...


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## NISFAN (Oct 11, 2003)

Cool, see this 

BMW regenerative braking


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## Pete G (Aug 18, 2008)

and this

Combined starter-alternator reduces petrol use: News from Dow Corning


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## ru' (Feb 18, 2007)

The alternator load on the engine will be pretty much proportional to the current it's producing, i.e. it will be a lot easier to spin if it's disconnected from the battery/electronics, and if the battery is flat and/or you're drawing a lot of current then it'll be a lot harder to spin.


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## Cris (Sep 17, 2007)

kismetcapitan said:


> oh, and a question about alternators. There's no clutch; the internal rotor is always spinning as far as I know. Is it when the regulator switches on, that resistance is created and a load placed on the engine? Just how many horsepower does an 80 amp alternator sap out of the engine? a 160 amp? I think I better hit Google...


the alternator is an electromagnet. it only drags on the engine in operation component drag aside. I forget whatthe conversion rate is but it's something like 20:1. if youcould getitto work under braking you'd stopa bit quickertoo. probably notenough to care about mind.


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## kismetcapitan (Nov 25, 2005)

Assuming a future retrofitted starter/alternator combo would be small enough to stick onto the RB26...perhaps start/stop usage could be effected on a Skyline as well.

One wouldn't want to do that until the engine was well up to temp though! But start-stop is a good idea; I remember first trying it out on the first generation Honda Insight. Works just like a golf cart - hit the gas pedal and you're rolling and the engine is starting all at once. If you wonder about the need for widespread implementation of start/stop technology, walk through a traffic jam, between the cars, during a summer day. When I'm threading my bike through traffic, it feels like the temperature shoots up an easy ten degrees. All that heat equals lost and wasted energy.

Would need a big battery though...or, hehe, a supercapacitor and a flywheel energy storage unit, as per the F1 cars 

I wonder if my 25,000th post here will be talking about the six flywheel boxes I've got in the boot, some polymer-technology battery pack where the rear seats used to be - and an 800kW electric motor where the RB26 used to be!


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## kingsley (Aug 26, 2002)

kismetcapitan said:


> current hybrids use the electric motor as a starter motor, so they've clearly sorted out whatever issue they were having.
> 
> Why (there must be a good reason) would an alternator produce AC which has to be converted to DC, when a dynamo could just produce DC from the start? Maybe for voltage regulation? (an alternator without a regulator would produce too much juice at high RPM - it makes peak power usually around 3000rpm, that much I know)


I'm not massively genned up on this topic so forgive me if I have some of this wrong.

Old cars used to be fitted with dynamos instead of alternators. Dynamos have a commutator, like an electric motor, so they produce DC (although the voltage wouldn't be constant, it never goes below zero, unlike an alternator).

Back in those days, dynamos couldn't really be revved beyond 6000rpm. Not sure why, maybe it was something to do with the commutator. Anyway, as a result of this, they were geared 1:1 with the engine.

The main problem was that they didn't start producing much output until about 1200rpm, which means that you're getting no charge on tickover and flat batteries were a potential problem with lots of slow driving.

Alternators could be revved faster and although these too didn't start producing decent charge until 1200rpm, because of their higher rev limits they could be geared 2:1 with the engine so you still got charge at tickover.

All the above from reading some 70s car books during my childhood so the info is a little old.

Cheers,
Kingsley.


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## ChristianR (May 31, 2005)

citroens wrc car uses kers like system..

Citroen WRC Hymotion4 | People | Racecar Engineering

saw it on dave, will give 100bhp increase, or can be used to drive inbetween stages emissions free and silent


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## Cris (Sep 17, 2007)

It strikes me that a system like this could be used to replicate the ATTESA system.

If you had a 'normal' RWD chassis with the front wheels connected to an electric motor (or small pair in the hubs). Usual guff about using the electric motor to slow the car, charge the battery etc. When the rear wheels start to slip the alternator steps in to 1 - decrease the torque output getting to the (rear) wheels 2 - supply energy to the front wheel motor/s. 'Leccy motors 'start up' quickly so the reaction time should be good. As part of a start-stop system you could use the front motors to pull the car forwards it traffic only using the engine beyond say 50% throttle or 10mph.

Of course you could have a Launch Control type mode which would use the engine and the motor and wouldn't have the alternator draw.


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## kismetcapitan (Nov 25, 2005)

Nissan's a step ahead of you, they've implemented "e-4WD" in the JDM Cube and March, although those cars are FWD with the rears engaging by computer control.

In a medium-tune 700bhp Skyline, the front needs to be able to pull 300bhp. But since even with ATTESA the power application is transient, maybe it's not power, but torque that needs to be applied. Some electric motors may only make, say 100bhp, but can yank out massive torque. I like the idea but it does boil down to weight.

The 2nd generation Toyota Prius' electric motor puts out a measly 67bhp - but makes 295lb/ft torque _from a standstill._ That makes me wonder - could a Prius electric motor pull as much as the Skyline's ATTESA, at the front wheels? There's obviously no separate starter motor on the Prius - the electric motor itself seems to serve as motor, starter, and generator.

I'm now quite keen on electric car development. Tesla can eek out what, 200km from their roadster? As batteries improve to give more range, there's a flipside - such a battery could deliver more power while maintaining a 200km range. This number is good enough for me - I don't get more than 200-300km per tank, and my driving habits have me filling up just 2~3 times a month.

Like I said before, I will keep my R32 forever. But the powertrain will change. I always thought the next step would be a 1000bhp monster RB30. But if electric technology moves fast enough in the next five years, I might just go all electric. It would be just as fun to build such a car too, because it'd require fabrication, and "tuning" of the control unit sending power to the motors - I would want four motors so I can have complete control over each wheel and maximize regeneration. But it may just make sense to connect a single massive electric motor to the Skyline drivetrain, and have the final drive still handled by the ATTESA system to maintain that classic "GT-R" handling.


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