InDetail: RBR KERS Battery case

Battery_top

During the F1 KERS era (2009-2013), Red Bull Racing adopted a unique battery set up. Rather than in a recess under the monocoque\fuel tank, the battery is split up into three separate units around the gearbox. I’ve explained the KERS installation in previous posts (LINK), but I’ve recently acquired a 3D printed mockup of one of the side mounted battery cases. This gives us some unique insight into the battery case’s dimensions and layout.

This is a mockup of the actual racecar battery case, 3D printed to be used by the R&D dept for planning and finalizing the car’s internal layout. Specifically, it’s a RB7 part, with the number RB7-RD-00907-01 inset into its surface.

Battery_pair

Like the real part, it’s made in top and bottom sections, although the real part would have been made from multiple carbon fibre sections bonded together to form the more complex lower section.

Battery_Hand
Looking at the battery case, the first thing that strikes you is its size, its tiny at just 23cm long (12cm wide x 17cm tall). Even with another of these batteries on the other side of the battery and a smaller unit inside the bellhousing, the car sported a very small volume of batteries. This may go to support the theory that Red Bull ran with a smaller capacity KERS than the regulations allowed, to save weight and space on the car. Albeit this was at the cost of a loss in KERS power and the small hard-worked system was frequently running too hot to be used constantly in race conditions.
Space inside the casing is limited with a volume of under 2000ccs. The actual battery case would have been made from Carbon fibre, housing the Battery cells, interconnecting bus bars, a cooling system and sensors for the Battery Management System (BMS). Of course none of this is evident in the empty mock up case, from the general shape of the casing you could however assume the cells were cylindrical (not pouch format. This arrangement fits in closely with the Renault battery supplier Saft’s products on its website (saftbatteries.com). Similar units are found on the website with weights of under 15Kg, one suspects that the Red Bull iteration would be far lighter.
Connections to the battery casing are for the; DC bus, cooling and BMS data. The positive and negative DC bus cables emerge from the hexagonal unions atop a top the casing. Pictures of the battery on the car show two separate DC cables emerge and combine into a single connector going into the gearbox and presumably into a series connection with the other two batteries.

RBR_Details
The outlets for the oil based dielectric fluid cooling emerge either side of the case, again joining to the rest of the batteries in a dedicated cooling circuit. It’s not clear where the BMS cables emerge, having seen some of the DC bus cables (see separate blog post LINK), these may be integrating into the sheathing around the DC cables, and thus emerge though the same outlets.
Mounting this battery case to the car, is via two anti-vibration mounts either side of the car, then a wide metal strap passing around its centre. I suspect this is the right hand battery judging by the orientation of its mounts and connector positions, thus there is another identical left hand battery and the horseshoe shaped unit inside the gearbox.

RBRKERS