F1 KERS batteries

[Hillhater]

After the first F1 race, it seems battery charge rates are becoming critical..
http://www.jamesallenonf1.com/2011/03/red-bull-using-start-only-kers/
I would have thought they would be using "Ultra Capacitors" rather than batteries for the high rate & short duration demand they have. I believe its over 60 kW for a few seconds.
Anyone got any better intel on these systems ?

 

[Arlo1]

Its been proven over and over and over that Lipo batterys OWN capacitors! And that was before the nano techs came out.
Capacitors are a waste of time for storing a large amount of energy!

 

[liveforphysics]

Its been proven over and over and over that Lipo batterys OWN capacitors! And that was before the nano techs came out.
Capacitors are a waste of time for storing a large amount of energy!

So true.

But, if eestor were to ever deliver, it would be game over for batteries.

 

[Xrain]

Some of the KERS systems actually use a mechanical momentum battery, spooling up a flywheel as a method of storage.

It's not really correct to say a capacitors are a waste of time, there a plenty of applications where a li-po battery would be terrible. Things like very high voltage systems, how many li-po's would it take to get up to 1 MV or even 1KV? while with a capacitor you could do that with just a single capacitor.

But your right as far as EV applications go capacitors are not very ideal as a primary method of storage. They could be a nice way to augment a standard battery however, using a battery for your energy storage, and then having some capacitors charge off of the battery to provide as much power as is needed for when you really stomp the throttle.

Takes some strain off of your battery pack not having to deal with pulse loads. Granted your controller tends to be the limiting factor for delivering current rather than your battery pack.

 

[Hillhater]

Its been proven over and over and over that Lipo batterys OWN capacitors! And that was before the nano techs came out.
Capacitors are a waste of time for storing a large amount of energy!

What sort of lipo pack is it going to be that can take a 60kW recharge in a few seconds ??

 

[liveforphysics]

Some of the KERS systems actually use a mechanical momentum battery, spooling up a flywheel as a method of storage.

It's not really correct to say a capacitors are a waste of time, there a plenty of applications where a li-po battery would be terrible. Things like very high voltage systems, how many li-po's would it take to get up to 1 MV or even 1KV? while with a capacitor you could do that with just a single capacitor.

But your right as far as EV applications go capacitors are not very ideal as a primary method of storage. They could be a nice way to augment a standard battery however, using a battery for your energy storage, and then having some capacitors charge off of the battery to provide as much power as is needed for when you really stomp the throttle.

Takes some strain off of your battery pack not having to deal with pulse loads. Granted your controller tends to be the limiting factor for delivering current rather than your battery pack.

Size the lipo correctly. A 10kw-hrs pack of Nano-tech's can discharge at 1MW (1300HP), continuously charge at 100kw, and could burst regen at 200kw. And 10kwhr is a pretty damn small pack for any non-bicycle EV.

 

[auraslip]

But, if eestor were to ever deliver, it would be game over for batteries.

The drama involved with that company is incredible. FOIA requests, sleazy journalists, pissed investors, slander websites, etc etc etc. It makes any promise of those caps coming out look very poor.

 

[liveforphysics]

But, if eestor were to ever deliver, it would be game over for batteries.

The drama involved with that company is incredible. FOIA requests, sleazy journalists, pissed investors, slander websites, etc etc etc. It makes any promise of those caps coming out look very poor.

Agreed. It may not be eestor that does it. But whomever cracks the ultra-cap voltage ~3v restrictionband pumping it up to >100v is going to end our use of batteries.

 

[Hillhater]

Size the lipo correctly. A 10kw-hrs pack of Nano-tech's can discharge at 1MW (1300HP), continuously charge at 100kw, and could burst regen at 200kw. And 10kwhr is a pretty damn small pack for any non-bicycle EV.

Exactly Luke, this is the point ...
regen rate is the critical determining factor and is at best 5 times longer than discharge rate, so for a KERS system used in a race ..( it has to regen the same amount as used each lap ?) .. where regen time is limited to braking periods , and F1 braking periods are very short ,.. probably only 10sec per lap available for max regen.
So they either have only 1 or 2 seconds of KERS boost per lap, or they have to use a much bigger battery than is actually needed for discharge capacity , just so they can regen sufficiently.
The F1 KERS actually need very little CAPACITY...
EG: lets assume they run a 375 volt system, and its capable of 60kW boost for 6 secs
( = 160A discharge, but only 0.10 kWhr capacity needed!)
Using known available Nanotech lipo (HK) , this could easily be done with 25 of the 4S, 2.2 Ahr packs, (=only 0.825 kWhr ?).
.. with a total weight of 7.8 kg. ( F1 teams probably have smaller Ahr high discharge packs of lower weight)
BUT, even at 20C charge rate (= 44A ) , you will need 22 secs of regen to recover that 0.1kWhr ...even at 100% eff !
Thats more than 2 laps worth of braking to regen the power used in one 6 sec boost !
The alternative would be to use a pack of more than double the size to be able to regen within the braking time available in one lap. ... but that would be extra weight to carry .

 

[theRealFury]

Size the lipo correctly. A 10kw-hrs pack of Nano-tech's can discharge at 1MW (1300HP), continuously charge at 100kw, and could burst regen at 200kw. And 10kwhr is a pretty damn small pack for any non-bicycle EV.

Exactly Luke, this is the point ...
regen rate is the critical determining factor and is at best 5 times longer than discharge rate, so for a KERS system used in a race ..( it has to regen the same amount as used each lap ?) .. where regen time is limited to braking periods , and F1 braking periods are very short ,.. probably only 10sec per lap available for max regen.
So they either have only 1 or 2 seconds of KERS boost per lap, or they have to use a much bigger battery than is actually needed for discharge capacity , just so they can regen sufficiently.
The F1 KERS actually need very little CAPACITY...
EG: lets assume they run a 375 volt system, and its capable of 60kW boost for 6 secs
( = 160A discharge, but only 0.10 kWhr capacity needed!)
Using known available Nanotech lipo (HK) , this could easily be done with 25 of the 4S, 2.2 Ahr packs, (=only 0.825 kWhr ?).
.. with a total weight of 7.8 kg. ( F1 teams probably have smaller Ahr high discharge packs of lower weight)
BUT, even at 20C charge rate (= 44A ) , you will need 22 secs of regen to recover that 0.1kWhr ...even at 100% eff !
Thats more than 2 laps worth of braking to regen the power used in one 6 sec boost !
The alternative would be to use a pack of more than double the size to be able to regen within the braking time available in one lap. ... but that would be extra weight to carry .

IIRC the KERS system total weight was in the 30-40kg area between the teams, i can't remember hearing anything about how much of that was the battery pack and how much the drive system but im guessing with the current state of battery tech that would be available to these guys the battery pack will still be in the nano tech area in performance, perhaps they are just running well above rated charge currents because lats face it, they can afford to change the battery pack every race / few races if they can afford to change entire engines every 2 or 3 races.

I remember reading an article on some KERS failures back when they were first using them and alot of the failures were due to overheating of the battery packs, possible BMS cutoff? anyway that would lead me to believe that they are running what ever battery tech they are using at the edge of its limits.

I have no idea if this statement is true and dont have the time to look into it but for all i know, Nano Tech / ultra high discharge lipo could have come into existance due to KERS or due to demand for ultra high discharge bettery tech for KERS.

---EDIT---

After reading the above press release from Red Bull Racing i saw the following

This “start only” system would give a gain in terms of weight distribution and packaging because such a system requires only a small battery, which is trickle charged, compared to the 20 kilo system that Red Bull’s rivals use. One of the reasons why the normal KERS batteries are large and heavy is for reasons of rapid charging.

20kilo of nano tech should be able to deliver 60kw burst and also charge the full used ammount in 1 lap of brakeing should it not?

 

[Hillhater]

I am sure the teams would be happy to replace the pack every race & every track session, but they dont want one to fail during a race..so they need to be sure of reliability for the 100 or so high rate charge cycles they see during a race.
The example i gave above was already based on 20C ,double the recommended max charge rate (10C) which i think is already risking reliability somewhat.
I doubt many people know how these packs last when they are being pushed through rapid charge discharge cycles continuously beyond their rated limits , every few seconds for 2 hours at a time !
I have also heard rumours of the KERS packs being around 20 kg in size ! ..

Edit:
I cannot find any arrangement of Turnigy Nanotech that would enable a 100A (10C) charge, ..with 20kg of cells.
if they wanted to keep within the 10C charge rate, they would need to use something like 20 of the 10S, 5 Ahr, Nano tech packs ( 100S , 2P ) so that they could charge at 100A for 10 sec per lap to regen the 0.10 kWhrs needed
.. But that would be 28kg of batteries ?

 

[Tiberius]

.. where regen time is limited to braking periods

Not sure this is correct. You could charge the battery any time the driver is not demanding full power. That gives you a lot more time than just the braking time. I suspect its the discharge rather than the charge rate that is the limiting factor.

Nick

 

[Hillhater]

. You could charge the battery any time the driver is not demanding full power. That gives you a lot more time than just the braking time.

Have you seen the Telemetry ?
.. Other than braking, there are not many periods when a F1 driver is not at 100% throttle.

Anyway, they are Kinetic Energy RECOVERY systems...not Series Hybrid drives .. IE the energy comes from retardation.

 

[theRealFury]

.. where regen time is limited to braking periods

Not sure this is correct. You could charge the battery any time the driver is not demanding full power. That gives you a lot more time than just the braking time. I suspect its the discharge rather than the charge rate that is the limiting factor.

Nick

As fas i can tell that wouldnt work, it would be like trying to ride an electric bike with regen break on all the time... and lets face it, if a F1 car isnt on the brakes its flat out on the throttle.

Batteries can usually discharge 5-10x as fast as they can charge, so if they can discharge over 6.67seconds then the charge limit would be 38-68 seconds so logically charge rate would be much more likely to be the limiting factor.

either way you look at it though if the FIA get their way F1 will be paving the way for EV's. the FIA intend to increase the output of the KERS to 120kw (160hp) (rumours of also increasing duration alowed per lap) and reduce the size of the ICE engine in 2013. They plan to slowly phase out the ICE engine as technology drives towards more sustainable electric output for racing. If i was a betting man id bet that F1 will be all electric within 20 years. lats face it, at 3.3 litres per lap consumption on an F1 car thats a 200 litre petrol tank... get rid of that and you have a whole lot of weight alowance for a battery pack as the tech advances with the added benefit of the car not changing weight as you get towards the end of the race so you have a level performance and will be able to guage tyre wear easier.

 

[Hillhater]

There is only so far they can go with a "KERS" system, as there is only so much KINETIC energy available to recover in one lap.
Much of the ICE energy is wasted in overcoming aero effects.
At some point they would have to become either series hybrids or full electric with KERS.

 

[Hillhater]

Capacitors are a waste of time for storing a large amount of energy!

Toyota Hybrid Race Car Wins Tokachi 24-Hour Race; In-Wheel Motors and Supercapacitors
17 July 2007
Hvr
The HV-R hybrid racer.

Toyota’s Supra HV-R hybrid race car won the Tokachi 24-Hour Race last weekend, marking the first time that a hybrid race car has won such a competition.

The car, which is based on the Supra GT used in Super GT races in Japan, uses a four-wheel energy regeneration and drive system which includes 10 kW in-wheel motors in the front wheels in addition to one 150 kW rear-axle mounted electric motor.

A quick-charging supercapacitor system provides energy storage for the vehicle.

 

[theRealFury]

There is only so far they can go with a "KERS" system, as there is only so much KINETIC energy available to recover in one lap.
Much of the ICE energy is wasted in overcoming aero effects.
At some point they would have to become either series hybrids or full electric with KERS.

I agree that there is only so far you can go with kers, im not sure of the formula but i know you can work out how much kinetic energy is stored in a 640kg f1car traveling at ~200mph and then work out the maximum you could recover from that in electrical innertia on the wheels or driveshaft. There is however some other areas that they could recover energy from at the moment. Brake temperatures is one thing that always seems to pleague F1 cars, if only they could find some way of drawing heat from the brakes and recovering it into electrical energy that would help keep the brakes cooler and supply additional charge, or they could just go with full E brakes and turn all the kinetic energy from the car into regen'd electrical energy. Im guessing that would need some major e-brake improvements to handle though.

Other areas include the exhaust temperature on a F1 car being in the high hundreds (~6-700'c iirc). Tapping into that lost heat energy would be beneficial also i guess?

then there is the forces of Gravity its self acting upon the car, can this be harnessed in any way to turn G forces into electrical energy?

As you can tell, im no scientist but i feel like there is a lot of waste that could be tapped into given the right technology to harvest it.sly some advancements would hinder others though so they would not be able to implement all of the above at the same time.

 

[Hillhater]

Interestingly i have found that if you use a 375v , 6.6Ahr pack made up from 200, 3.3 Ahr cells . (100S ,2P )..of HK's 90C Nano tech.
you get a 21kg pack, capable of 100A charge rate at 15C .. and over 200kW discharge ..but still only 2.5kWhr capacity
... interesting in that it comes to that 21kg figure ?? ...co-incidence ?

 

[theRealFury]

Interestingly i have found that if you use a 375v , 6.6Ahr pack made up from 200, 3.3 Ahr cells . (100S ,2P )..of HK's 90C Nano tech.
you get a 21kg pack, capable of 100A charge rate at 15C .. and over 200kW discharge ..but still only 2.5kWhr capacity
... interesting in that it comes to that 21kg figure ?? ...co-incidence ?

Well further reading seems to suggest that the total weight of the KERS system including any cooling and the drive system (motor alleged 5-8kg) is ~20kg so that would put the battery in the 10-15kg range, has any testing actually been done by anyone on this forum to test just how much burst charge a nano tech lipo can take, i would have thought that like with discharging the charge aspect would be capable of more burst current than constant current. maybe a nano tech can be burst charged at 20-30c for a few seconds with adequite cooling and take and hold the full or most of it? I know it would degrade the cell life a lot but im sure they would not be too fussed about that if they can power the thing with $1000 of lipo as long as it lasted a couple of hundred part cycles cycles.

further on the above i believe that lipos ability to discharge and charge effectively changes with the SOC of the cell. For instance im under the understanding that in the 30-70% SOC window the battery will be capable of taking higher charge rates than a almost full / flat battery without causing damage? May7be they use this to their advantage as well?

 

[Hillhater]

......has any testing actually been done by anyone on this forum to test just how much burst charge a nano tech lipo can take,....

Yes, Luke, ( liveforphysics ) has done this and posted earlier that good Nano techs can handle 100C discharge bursts and 20C charge bursts.
But, i doubt there is anyone outside the KERS developers who has cycled those burst rates continuously every few seconds for a 2 hour period !

This is what is needed ...400C charge capability !
http://www.greencarcongress.com/2011/03/braun-20110321.html

 

[theRealFury]

This is what is needed ...400C charge capability !
http://www.greencarcongress.com/2011/03/braun-20110321.html

Yea, i saw that article a few weeks ago, advancements in nano and mollecular level construction hold the most promise for battery improvements imo.

 

[Hillhater]

http://www.greencarcongress.com/2010/11/hondas-f1-kers-motor-60-kw-21000-rpm-7-kg.html#more

The 106-cell lithium-ion battery pack was mounted in the forward section of the vehicle’s keel to preserve the vehicle’s center of gravity and take advantage of draft air cooling.

Another site suggested that Ferrari at least were using batteries supplied by SAFT

So, that seems to confirm they are running a 400V Lipo system ,..as suspected... ( my 375 volt guess was close ! :wink: )

 

[theRealFury]

http://www.greencarcongress.com/2010/11/hondas-f1-kers-motor-60-kw-21000-rpm-7-kg.html#more

The 106-cell lithium-ion battery pack was mounted in the forward section of the vehicle’s keel to preserve the vehicle’s center of gravity and take advantage of draft air cooling.

Another site suggested that Ferrari at least were using batteries supplied by SAFT

So, that seems to confirm they are running a 400V Lipo system ,..as suspected... ( my 375 volt guess was close ! :wink: )

A nice find! at least we now know that F1 kers battery packs are Lipo. In my head i didnt think they would have run a 106s1p setup though as that would put alot of amps into a single P cell, is it not possible they are running 53s2P for ~ 200v and half the regen load per cell?

 

[Hillhater]

... In my head i didnt think they would have run a 106s1p setup though as that would put alot of amps into a single P cell, is it not possible they are running 53s2P for ~ 200v and half the regen load per cell?

If you half the voltage , you double the amps, which actually leaves you in the same situation !
60Kw on a 400v system is 150A . That is not a problem for a 2Ahr Nano tech cell at 75C discharge.
Charging at 15C is an issue though... ideally you would need a 10Ahr pack ..5 times bigger !

 

[liveforphysics]

... In my head i didnt think they would have run a 106s1p setup though as that would put alot of amps into a single P cell, is it not possible they are running 53s2P for ~ 200v and half the regen load per cell?

If you half the voltage , you double the amps, which actually leaves you in the same situation !
60Kw on a 400v system is 150A . That is not a problem for a 2Ahr Nano tech cell at 75C discharge.
Charging at 15C is an issue though... ideally you would need a 10Ahr pack ..5 times bigger !

Why is charging at 15C an issue? I put up some graphs of continuous 15C charge on a nano-tech pack from empty to full. It barely got warm.