Kers in F1. Lipo and powerful electric motor
 

I know it is not a Rc topic, but I think it is strictly related to the materials we all use, Lipo batteries and electric motor, so I would like to hear your opinion.
In the 2009 season on the F1 race cars Kers will be introduced. During brake this system charges batteries and it can give till extra 58 Kw power for more than 6 seconds in
every lap. In a F1 car everything is light and small as possible, so I really cannot understand where designers can find the space to place the batteries and the powerful
electric motor. Can you help me guessing the overall dimension and weight of the batteries and the motor ?
I have what I think is a powerful Lipo pack (3s 2100mAh 20C) so at the maximum discharge it gives 2.1x20x11.1 = 466 W of power. So, in order to have 58 Kw more than 100
batteries are needed. The weight may not be a concern, it is 140gr x100 = 14 Kg, but the volume is big considering the dimensions of a car.
Besides Lipo packs are much more dangerous than traditional Nimh packs because they are flammable and they may explode, so I don't think it is safe to fill a racing car with
them. According to rumors the motor will be feed with high voltage connecting lots of lipo packs in series till 700 V in order to limit the current under 100 A.
Am I wrong or such high voltages kill people ?

Thanks

Filippo

Anything over 50v can arc on skin, so yes high voltage can kill.

It will become an issue with the regenerative capacity of the pack, or how fast it can recharge. I don't think many teams will be able to hit the 58kw power level without some big compromises this year. Battery weight and size is certainly one of them. Life has much faster recharge than LiCo technology, so we may see this used instead. I shorted a 12s LiFe pack into a 6s pack by accident for a split second and put a whole .5 amp hour back into the smaller pack.

I am very interested to see the execution of designs in this, and to see how much more fuel economy can be had. THIS new rule in f1 racing will certainly trickle to cars around the world, and probably drastically change our fuel efficiency and hybrid car technology.

The question for f1 cars is whether the extra weight will be made up in longer times between refueling.

With that kind of discharge and amp, a normal battery will heat up too quickly and melt. Think capacitors, and think LARGE light weight capacitors. Since there's no need to store the energy long term like say in a battery, capacitors are the answer to your question.

I think it is not easy to store 400 KJ inside capacitors. Anyway I considered the discarge of a battery @ 20C, but the charge is perhaps the most critical phase because standard battery have the charging limit of 1C. Don't know anything about LiFe but assuming Fe stands for iron they could be too heavy.

Bye
Filippo

Maybe these guys have special batteries. I know military has LiCo that will do 100C discharge, so maybe there are chemistries with faster charge rates that are not on the market.

Energy can either be stored as mechanical energy (as in a flywheel) or can be stored as electrical energy (as in a battery or supercapacitor).

The flywheel would be easy, problem would be its gyro type effect on the vehicle depending its placement and rotation direction. I bet it will be a super capacitor, especially since it will be a quick charge, and only allowed for 1 lap. Likely the teams will only use the KERS to garner power right before the straight, then use it on the straight.

I don't like it for the dangers already seen:
“During testing of the KERS car at the Jerez track this morning, there was an incident involving a mechanic. When the car returned to the pits, he touched it and suffered an electric shock. He sustained slight injuries to his left hand and grazing on his left arm. After a brief examination at the track’s medical centre, he has returned to the test team.”

The mechanical KERS system utilises flywheel technology developed by Flybrid Systems to recover and store a moving vehicle’s kinetic energy which is otherwise wasted when the vehicle is decelerated. The energy is received from the driveline through the Torotrak CVT, engineered and supplied by Xtrac, as the vehicle decelerates, and is subsequently released back into the driveline, again through the CVT, as the vehicle accelerates. The FIA has defined the amount of energy recovery for the 2009 season as 400kJ per lap giving the driver an extra 80hp over a period of 6.67 seconds.

“Compared to the alternative of electrical-battery systems, the mechanical KERS system provides a significantly more compact, efficient, lighter and environmentally-friendly solution.