F1technical.net

OK, found that a typical KERS system weighs 35kg from Formula 1 official website. I'm guessing this is a bit high by todays standards, but I have no idea. The max ES is 400kJ. The increase for 2014 is to 4MJ, 10x. I don't know how energy storage weight increases vs energy capacity. I'll make an assumption that the battery part is roughly a third of the weight, that's 10kg for batteries to store 400kJ. Increase the capacity to 4MJ and if weight increase is linear, that's 100kgs worth of batteries.

dren wrote:OK, found that a typical KERS system weighs 35kg from Formula 1 official website. I'm guessing this is a bit high by todays standards, but I have no idea. The max ES is 400kJ. The increase for 2014 is to 4MJ, 10x. I don't know how energy storage weight increases vs energy capacity. I'll make an assumption that the battery part is roughly a third of the weight, that's 10kg for batteries to store 400kJ. Increase the capacity to 4MJ and if weight increase is linear, that's 100kgs worth of batteries.

Interesting as what you say is, I have some trouble with those numbers. I took the SLS AMG Electric Drive for comparison to get a rough idea how energy relates to weight

"The high-voltage battery in the SLS AMG Coupé Electric Drive boasts an energy content of 60 kWh, an electric load potential of 600 kW and weighs 548 kg" (source)

That's 216 MJ at 548 kg if I'm not mistaken. If we were to go by this number and the relation between energy storage and weight was linear, the batteries to store 4 MJ would weigh in at around 10 kg. That's a factor 10 off of your figures.

tim|away wrote:A couple of thoughts on the weight changes for 2014:

- the minimum weight has been increased to 690kg, up from 642kg this year
- fuel load will be down by roughly 50 kg (see my post above)

That leaves us with at least ~100kg for ERS and the turbo and the additional cooling. Worse still, this allowance doesn't take into account that the engines will be lighter due to fewer cylinders or the lack of KERS unit in 2014. Having said that, even a 100 kg allowance for the turbo, ERS and addtional cooling does seem rather excssive if you consider that the whole V8 engines this year weigh slightly less than that (95kg) - realistically this allowance is probably more than 130kg even (and that is a somewhat conservative guess). Have they increased the weight limit a bit too much?

The MGUs will be fairly heavy with 120 kW and and perhaps 45 kW respectively. Have a look what what a conventional AC servo motor of that power weights.

In the meantime I have done some calculations based on the Renault figures and here is what I got:
average lap length = 5.23 km
average speed = 197.95 km/h
average full throttle percentage = 56.54%
====>
average lap time = 96.5 s
======>
average full throttle time = 54.5 s
========>
power from 100% ES (2MJ) in race = 36.7 kW = 49.2 bhp
power from 100% ES (4MJ) in quali = 73.4 kW = 98.4 bhp

If we assume that 10% of the ES energy is consumed under lower throttle conditions to power out of corners we can only use 90% of the ES energy and we get a reduction of the final power from ES.

power from 90% ES (1.8MJ) = 33.03 kW = 44.3 bhp
power from 90% ES (3.6MJ) = 66.06 kW = 88.6 bhp

So if the Renault figure of 750 bhp from March 2013 includes the ES race power it would leave 705.7 bhp compounded at the crank from the engine and the excess turbine power.

If we take away 650 bhp for the engine we are left with 55.7 bhp at the crank which would give us 61.88 bhp excess power at the turbine. This is 9.5 % of the engine power. My estimate was 9.2%. You see that my previous estimate was even 0.3% lower than the figure we get from what Renault were predicting in March. And this assumes we have taken 44.3 bhp out of the 750 bhp figure for the ES in race mode on an average F1 lap.

tim|away wrote:

dren wrote:OK, found that a typical KERS system weighs 35kg from Formula 1 official website. I'm guessing this is a bit high by todays standards, but I have no idea. The max ES is 400kJ. The increase for 2014 is to 4MJ, 10x. I don't know how energy storage weight increases vs energy capacity. I'll make an assumption that the battery part is roughly a third of the weight, that's 10kg for batteries to store 400kJ. Increase the capacity to 4MJ and if weight increase is linear, that's 100kgs worth of batteries.

Interesting as what you say is, I have some trouble with those numbers. I took the SLS AMG Electric Drive for comparison to get a rough idea how energy relates to weight

"The high-voltage battery in the SLS AMG Coupé Electric Drive boasts an energy content of 60 kWh, an electric load potential of 600 kW and weighs 548 kg" (source)

That's 216 MJ at 548 kg if I'm not mistaken. If we were to go by this number and the relation between energy storage and weight was linear, the batteries to store 4 MJ would weigh in at around 10 kg. That's a factor 10 off of your figures.

You cannot use that SLS AMG figure because the battery is designed to last several years. F1 batteries are throw away items. They will be exchanged for every race. It means that they can thermally stress the batteries much harder and have to carry much less weight.

WhiteBlue wrote:You cannot use that SLS AMG figure because the battery is designed to last several years. F1 batteries are throw away items. They will be exchanged for every race. It means that they can thermally stress the batteries much harder and have to carry much less weight.

I am very well aware of that, but that would reduce the weight even more and supports my point. As for your previous post (which was very interesting by the way), I also looked up the powertrain of the SLS AMG electric drive for comparison.

"The SLS AMG Electric Drive will be powered by four electric motors with combined ratings of 552 kW (751 PS; 740 hp) and 1,000 N·m (738 lb·ft). Each motor can spin up to 13,000 rpm and weighs 45 kg (99 lb)." (source)

4 electric motors producing 138kW each (as opposed to 120kW), weighing 45kg.

Let me sum this up:
- fuel load reduced by 50kg in 2014
- no KERS in 2014 (30kg ish)
- increased minimum weight in 2014 (48 kg).
- lighter engines (unsure about weight difference between the 1.6 V6 and the current V8)

That brings me to an allowance of easily over 130kg. At the moment I'm assuming 45kg for the electric engine and 10kg for the batteries and that's judging by road car technology (!). You would rightly argue that F1 would get the weight down even more, which is why I raised the point of the seemingly excessive increase of minimum weight in the first place. With road car technology, I am left with a stagging 75kg+ for cooling and a turbo with this allowance - and that's not even taking into account that the V6 will be significantly lighter than the V8 which would increase that allowance even more.

I'm getting a bit different figures:
http://www.formel1.de/news/news/2013-08 ... -zeitalter
The data from there:
V8 naked was 95kg
V8 with KERS was 120 kg
V6 total power unit package (not including batteries according to regulations) is 145 kg
V6 total package including all additional systems not in regulation weight 180 kg

My estimate from there is the following:

V8 KERS = MGU 60kW including inverter + Batteries = 25 kg
battries = 3.5 kg (0.4 MJ)
MGU total 21.5 kg for 60 kW
specific weight MGUs including inverters = 0.358 kg/kW
specific weight batteries = 8.75 kg/MJ

V6 naked (71 kg) + turbine and compressor (9 kg), without MGU-H = 80 kg estimate
2 MGUs (MGU-H + MGU-K @ 45 + 120 kW = 165 kW) = 59 kg
Intercooler and plumbing = 6 kg
batteries = 35 kg (4MJ)
=====================
total V6 = 180 kg

So the V6 turbo with compressor, turbine, intercooler and plumbing would come to a naked weight (no MGU-H) = 86 kg.
V6 including all above + MGU-H = 102 kg
V6 including all above + MGU-K = 145 kg
V6 including all above + batteries = 180 kg

If you take out the energy recovery package (25 kg) from the 2013 car you could run the V8 car at 617 kg.
If you take out the energy recovery package (94 kg) from the 2014 car you could run the V6 car at 596 kg.
Not such a big difference IMO.

On the grid weight with race fuel for the 2014 car is 800 kg
On the grid weight with race fuel for the 2013 car is 797 kg

Minimum weigt after race 2013 car is 642 kg
Minimum weight after race 2014 car is 690 kg

The starting weight is about the same. The arrival weight for the 2014 car is 48 kg heavier. If you compute the average race difference in weight you get 25 kg. This will add about 1 s initially to your lap time, if we had the same power and aero.

http://grandprix247.com/2013/08/05/rena ... ears-cars/

But we have already heard that the 2014 cars are expected to get faster lap times in 2014. Because we also have reduced aero efficiency it means we will have more power than we had in 2014.

tim|away wrote:

dren wrote:OK, found that a typical KERS system weighs 35kg from Formula 1 official website. I'm guessing this is a bit high by todays standards, but I have no idea. The max ES is 400kJ. The increase for 2014 is to 4MJ, 10x. I don't know how energy storage weight increases vs energy capacity. I'll make an assumption that the battery part is roughly a third of the weight, that's 10kg for batteries to store 400kJ. Increase the capacity to 4MJ and if weight increase is linear, that's 100kgs worth of batteries.

Interesting as what you say is, I have some trouble with those numbers. I took the SLS AMG Electric Drive for comparison to get a rough idea how energy relates to weight

"The high-voltage battery in the SLS AMG Coupé Electric Drive boasts an energy content of 60 kWh, an electric load potential of 600 kW and weighs 548 kg" (source)

That's 216 MJ at 548 kg if I'm not mistaken. If we were to go by this number and the relation between energy storage and weight was linear, the batteries to store 4 MJ would weigh in at around 10 kg. That's a factor 10 off of your figures.

http://www.greencarcongress.com/2010/11 ... -7-kg.html

This states the Honda motor was to be 6.9kg. James Allen stated in an older article that teams were using a 20kg system :http://www.jamesallenonf1.com/2011/03/r ... only-kers/. If that's the case, that leaves around 13 or so kilos for the batteries and controls. So 10kg may not be too far off for 2013 batteries?

If you use Honda's achieved 7.8kW/kg, you get 15.4kg for a 120kW motor if the ratio scales. You can figure the MGUH weight as well.

No way! We have pretty solid data that the batteries are 35 kg in 2014 for a capacity of 4MJ.

http://www.tm4.com/AxisDocument.aspx?id ... %a4_HD.pdf

Here you find a specification for an automotive motor and inverter. This is general automotive technology and not F1 level. They achieve 1.7 kg/kW. F1 would have to do 5 times better.

WhiteBlue wrote:No way! We have pretty solid data that the batteries are 35 kg in 2014 for a capacity of 4MJ.

I was guessing 10kg for batteries now in 2013... I'm assuming you're refering to me?

And it looks like they are designed with a power to weight ratio and packaging concerns foremost. The Honda unit was only 90% of max allowable power. So how likely are we to see max allowable power initially?

WhiteBlue wrote:No way! We have pretty solid data that the batteries are 35 kg in 2014 for a capacity of 4MJ.

sounds very heavy, I looked up the Tesla battery 450Kg- 200MJ, so 9Kg - 4MJ

langwadt wrote:

WhiteBlue wrote:No way! We have pretty solid data that the batteries are 35 kg in 2014 for a capacity of 4MJ.

sounds very heavy, I looked up the Tesla battery 450Kg- 200MJ, so 9Kg - 4MJ

2.25 kg/MJ compared to the SLS AMG figure of 2.53 kg/MJ
I still think that the loading and unloading gradient determines the weight of the battery and not the raw capacity.

In F1 you need to drain the 4MJ in an average time of 55s. In a road car you probably take 100 times more time. Hence you need to install vastly more capacity than you actually are going to store. You are limited by the storing and draining rate.

Some years ago on this board we have looked at battery weight and performance figures. We found just the same thing. Installed capacity is determined by your charging and depletion rate, not by the capacity the battery can hold.

Edit: Found it http://www.f1technical.net/forum/viewto ... 31#p215231 It was 747heavy who kicked off the discussion on Xmas 2010 on this thread. I'm pretty sure I went through all his figures in another thread at that time but I cannot find it any more.

http://www.teslamotors.com/fr_CA/forum/ ... -battery-0

Model S:
Largest battery holds 85kWh (306MJ). Motor makes 310kWs.

They are estimating 535kg to 556kgs, but I can't find an actual number.

dren wrote:http://www.teslamotors.com/fr_CA/forum/ ... -battery-0
Model S:
Largest battery holds 85kWh (306MJ). Motor makes 310kWs.
They are estimating 535kg to 556kgs, but I can't find an actual number.

The battery capacity of an F1 is not determined by the unloading or drainage speed but by the loading speed. You have 55s to drain 4MJ but you have only 8s to load 2 MJ because of the limited braking time. So the critical transfer rate is 225 kJ/s or 225 kW charging power. If you compare that to the Tesla motor that drains at 306 kW you get a percentage of 72.6%. The F1 battery would have to weight 400 kg. or the installed capacity would be 223 MJ. I think F1 is not doing so bad with 35 kg for this kind of charging rate.

Right. If you use the 93% generating efficiency the Honda KERS had, you're looking at a time of 18 seconds needed during a lap to charge 2MJ, and that's assuming the motor will be designed for the full 120kW output. And like I stated before, all 100% braking energy will not go into the MGUK during braking. So we are either looking at a much smaller battery storage system, a much larger recovery from the MGUH, or an overall reduction in the ERS size, weight and output.

dren wrote:Right. If you use the 93% generating efficiency the Honda KERS had, you're looking at a time of 18 seconds needed during a lap to charge 2MJ, and that's assuming the motor will be designed for the full 120kW output. And like I stated before, all 100% braking energy will not go into the MGUK during braking. So we are either looking at a much smaller battery storage system, a much larger recovery from the MGUH, or an overall reduction in the ERS size, weight and output.

You are jumping to the wrong conclusions IMO.
The battery capacity in 2014 is not the 4 MJ that is allowed to transfer. The battery capacity is probably ten times higher because it is determined by the time that is available to charge 2 MJ under braking. My best guess at the moment is that we will have battery capacity of 40 MJ in reality in order to be able to charge the battery in the short time. But all of this is a bit speculative. Teams are likely to use a combination of supercaps and batteries as Red Bull are already doing. So I cannot give you any more accurate figure than the 35 kg I estimated from the German language Renault report. I will keep serching for more Renoult statements in case they have given info on battery weight at some time.