So Performance Mode is unfriendly to battery life. I am I correct here?
In general, yes. Performance mode allows the battery to run hotter to get more power out of the battery. I have a 2008, and FWICT, there is no difference in torque between standard and performance. At least I've never notice getting less power in Standard. On the 2010 sport there is definitely a difference.
vfx said:
I believe it's only bad for the battery if the car's battery pack is allowed to get hot and stay hot -which is what Performance Mode allows. So if you don't charge in Performance Mode then before puttering* around in the city for 20 minutes without any (or few) wildly fun acceleration while in Performance Mode would not hurt anything since the battery would not get hot. Or will it?
It's more complicated because there are two bad things you are trading off against. High temperature and high current draw. To get the most power from the battery (and do the least "damage"), you want the battery to be hot (40C) and fully charged. Leaving the battery hot and fully charged degrades the battery over time. The opposite, a cold, fully charged battery driven in performance mode is probably worse because for the same power the PEM will draw even more current to compensate for the lower battery voltage. But the worst case of all is a cold battery at less than 50% SOC in performance mode. The internal resistance of the battery is higher at low SOC causing more battery heating. So if you drive in performance with a cold, <50% SOC battery, the battery will deliver larger current and it will also experience rapid heating of the battery.
I think Tesla has it right. If you are using Performance mode, make sure the battery is warm and fully charged. When you are done, plug it in. (charge it in standard to cool it back down). When you are below 50% take it easy on the accelerator, and don't drive in performance mode.
Scott is there a way to tell when the battery has crossed over into "Degradation Mode"?
When the third blue bar on the VDS battery screen comes on, that means the battery is at 35C. The fourth means 40C. So for performance, it's probably good have the third bar on. For standard driving, I try to charge whenever I notice that the third bar is on, or the SOC has fallen below 50% YMMV.
So the roadster battery doesn't like to be rode hard and put away wet :smile: So that spirited drive to the grocery store in performance heating the battery to 40C and then left in the garage for 5 hours waiting to charge at the cheap TOU, means the battery spent 5 hours @ 40C. When in doubt, plug it in [and charge it]!