SAFT providing Li-ion cells for KERS systems for 5 of 12 competing F1 teams
11 April 2011
Saft will provide lithium-ion (Li-ion) batteries for the KERS systems for five of the twelve Formula 1 teams competing this season, including Ferrari and Lotus Renault GP.
Saft worked with the F1 teams to develop solutions for each team’s KERS design, based on Saft VL Li-ion cells. Lifetime and durability were key considerations since the batteries are subjected to high levels of heat and vibration.
Our solutions for KERS demonstrate Saft’s ability to deliver leading-edge technology for the most complex and demanding high performance applications, even while working to extremely tight deadlines. We are aiming to establish our Li-ion batteries as the reference for Formula 1.
—Xavier Delacroix, General Manager of Saft’s IBG division
When the F1 car brakes, a proportion of its kinetic energy is captured by an electric motor/generator (MGU) connected mechanically to the engine. This captured kinetic energy is converted into electrical energy which is stored in the Saft Li-ion cells. When extra power is needed, the battery releases the stored energy to the MGU which functions as an electric motor, providing extra power to the drive train.
The KERS system allows up to 60 kW boost (around 80 horsepower), with an energy release up to 400 kJ per lap. The driver can use this additional power to provide an extra seven-second boost of acceleration in each lap.
The link provided for the small VL cells is probably not the correct cell range (4C pulse current would not be nearly power-dense enough). Given the high power requirements, I would think the teams are more likely using Saft's VLV cells. Here is a link: http://www.saftbatteries.com/Produit_Large_VLV_cell_range_301_64/Language/en-US/Default.aspx
Posted by: ZachF | 11 April 2011 at 01:11 PM
Why???
These Saft caps have "OK" energy density at 174Wh/kg but their power rate is very poor at only .695kW/kg... and that is only in pulse mode.
To get 60kW of power then, you'd need 86kg worth of batteries to get the bloody power you would need! Sure the energy density would be over the top then, but you can only use 400kJ per lap..that is ONLY .11kWh!!!
That is like adding a very heavy extra driver in the car so you can get 6.6 seconds of 60kW??? The limiting factor here is the power, not the energy density.
Why not go for the A123 cells or something? They were at 5,300Wh/kg last I looked and their energy density was in the 160Wh/kg in energy density so you could easily have a ~12kg pack. These guys kill for a couple of kg so why would you not go with something like that A123s?
And who cares if they have to buy an extra battery pack or two during the season? These guys have a $2+million per year budget for engines on EACH car so why skimp on batteries for the KERS system?
Posted by: DaveD | 11 April 2011 at 01:12 PM
Uhhhh, make that Saft batteries. I guess I was thinking about "supercaps" and Saft caps came out :-)
Posted by: DaveD | 11 April 2011 at 01:16 PM
ZachF,
Thanks for that pointer. Now that makes much more sense as those cells have nearly identical specs of the A123 cells. There "ultra high power" cells do a continuous output of about 5.2kW/kg and pulse for 2 seconds at 7.5kW/kg:
http://www.saftbatteries.com/doc/Documents/defence/Cube769/VL5U_cell_data_sheet.a2c55356-164e-4fe3-b957-86bbed023422.pdf
Posted by: DaveD | 11 April 2011 at 01:43 PM
In 2009, Mercedes / Maclaren were using A123 cells, and in F1 spec they were reported to be putting out approximately 20 kW per kg.
http://www.greencarcongress.com/2009/07/mclaren-20090727.html#tp
Why other teams don't use A123 or titanate seems a bit odd.
Posted by: clett | 12 April 2011 at 01:35 AM
I hope they will remove restrictions on KERS and allow them to be used as much as team want to use them.
There is also a slight issue that the KERS system makes the rear brake balance higher than the front as KERS ER's. The simple solution to this is to add another 60kW motor to the front axle
Posted by: 3PeaceSweet | 12 April 2011 at 11:39 AM
3Peace,
Yeah, I was thinking the same thing. I guess they don't want to deal with the extra weight and a drive train in the front of the chasis.
If they lifted the silly restrictions of only .11kWh per lap, then it would possibly pay for the weight penalty but with that arbitrary limitation, it is just a lot of dead weight in the front of the car to screw up their balance.
Posted by: DaveD | 12 April 2011 at 12:01 PM
AFAIK most F1 cars carry ballast to make them up to a minimum required weight. This being the case having extra weight on the front axle might not be too much of a problem
Posted by: 3PeaceSweet | 12 April 2011 at 01:23 PM