I wanted to provide everyone with an update on how things are coming along with solving the overheating issues with the Performance 3. In collaboration with Mountain Pass Performance, I am happy to report that we have had some breakthroughs with cooling the drivetrain.
To begin with, we replaced the powertrain coolant loop radiator with a unit that had approximately 6x the cooling capacity. In testing, we found that the drive unit inverter temperatures dropped significantly. Unfortunately, this did not have much of an effect on the time it took before current draw was limited.
Next, we fitted an oil cooler to the rear drive unit. Upon testing, we found that the rear drive unit inverter temperatures dropped even lower, the oil temperatures dropped significantly, and the rotor and stator temperatures also reacted positively. Further analysis has found no adverse effects during Supercharging, and everything operates normally until the fan on the oil cooler is turned on. On the LR RWD Model 3 this completely solved current limiting! On the Performance, we found that the Drive Unit was no longer overheating! However, this did not completely resolve the current draw being limited on the Performance.
So, we fitted an oil cooler on the front drive unit as well. Testing was as expected, and the front drive unit responded in much the same way as the rear drive unit. Temperatures dropped in all regards, Supercharging speed was not affected, and the powertrain was now operating at near-ideal temperatures even under sustained heavy load. Now that we knew the drive unit cooling was completely solved, we moved on to the next piece of the puzzle.
With the concern still present, we were finding a clear correlation between the battery hitting a certain temperature and the current draw being limited. What came next was the addition of a radiator on the high voltage battery loop. The results were very positive – the battery temperature dropped almost 10C over the same time period, and the coolant inlet temperatures were much easier to manage and to sustain at considerably lower temperatures. This improvement, along with the other modifications, does appear to yield about nearly a 20% increase of on-track time before current limiting comes into play.
That all being said, there is one more component we have identified as being the weak link in the system, and ultimately needs to be resolved before we can conclude that the concern is fully eliminated. We kept this for last, as it will be the most difficult problem to overcome. On the bright side, we are already working on a solution and are confident that in time it can be fixed. Stay tuned for more information, as we should have this problem ironed out soon, so that you all can keep turning fast laps for the full session – not just part of it!
P.S. Please note some of the modifications pictured are purely prototypes for testing and are not indicative of the final product.