Our electric race car is very similar to a Formula-E car: they drive short circuits, accelerate very quickly, and power everything from a large battery pack. Our accumulator, as we call it, has around 7 kWh and contains 288 lithium cells.
These cells are pouch cells, based on a Lithium Cobalt Oxide chemistry, which means they can supply a lot of current and have a high capacity. These Lithium cells are very much like the battery inside your mobile phone.
As we all know, batteries need to be kept comfortable. Put them in a too small container, and you get situations like what happened to a certain type of big-brand phones a few years ago. The batteries in these phones were packaged too tightly and are now not allowed on airplanes anymore.
Besides space, batteries also need to stay at just the right temperature, and the right voltage. If they go outside of their comfortable range, at the very least the batteries become less healthy (so they run out sooner). In the worst case, they can even catch fire.
This is called ‘thermal runaway’, look it up.
So, it’s very important to keep all the almost 300 batteries happy and healthy, to keep our driver and car happy and healthy. I’ll explain in a bit how we keep that in check for our accumulator but, let me first go into its overall functions.