The effect of Performance mode on battery life

[richkae]

A few days ago I spent the day lapping at a racetrack. ( Go-kart track, 0.9 miles, 18 turns, my max speed was about 74mph )

My car is an early 2.0 non-sport.
I drove in performance mode. In between sessions I charged in standard mode 240V 40amps.
I ended each session when I hit the power limit due to motor temperature.
Ambient temperature was about 24C

It took about 7 minutes of hard driving to hit reduced power due to motor temperature.
A typical session the motor would start at 61C and then hit 147C and then I would do a couple cool down laps.
It would take about 4-5 minutes for me to stop and plug back in. About 18-20 minutes later the motor would be down to 61C and ready to go again.
The PEM would start out at 35C and peak out at 45C, but be back down to 35C by the time I parked.
The ESS would gain about 9-10 C by the end of the session. An early session it started at 24C, was at 33C when I stopped, but be back down to 28C after 18 minutes plugged in. So each session I drove, the ESS gained a little bit of temperature, slowly climbing during the day.
The later sessions it started between 28C and 30C and peaked out at 38C or so.

If I had charged in perfomance mode, the ESS would have cooled less. I believe that I would have gotten slightly more power out of it because of that - but that does not seem worth it because getting it hot reduces its life.

The next time I go, if the battery approaches 40C I will charge in range mode to cool it down a little more in between sessions.

[S-2000 Roadster]

The next time I go, if the battery approaches 40C I will charge in range mode to cool it down a little more in between sessions.

Is there any documentation showing the Range mode keeps the battery cooler during charging? I thought it would have to allow more heat to build up in order to reach 100% charge. My assumption is that Standard mode is the coolest when charging, but it stops at 90% full. Range most seems to be designed to reach 100% charge, not necessarily to charge at a cooler temperature.

[smorgasbord]

Is there any documentation showing the Range mode keeps the battery cooler during charging?

I don't have anything handy, but that was confirmed to me by my Customer Advocate. The idea is to use line power to pre-cool the battery, thus saving the need to pull juice out of the battery to cool it.

[S-2000 Roadster]

The idea is to use line power to pre-cool the battery, thus saving the need to pull juice out of the battery to cool it.

Nice! When charging in Ellensburg, Washington, recently, I used Range mode until the current dropped below the full 70 A. Thus, I supposedly avoided any of the drawbacks of charging to 100%, but still gained the advantage of a pre-cooled battery.

[Nik]

*Can you even really "putter" in and electric car?

I think one would trickle around in an EV.

[vfx]

I think one would trickle around in an EV.

I'm going to go with "buzz".

[daniel]

*Can you even really "putter" in [an] electric car?

Yes, definitely. In my Zap Xebra I can do nothing but putter. Well, it doesn't putt, but it kind of klunks and clanks. But (sorry to get pedantic here) "putter" in common usage doesn't mean making putt-putt noises so much as it means to go slowly here and there, semi-aimlessly. Not every EV is a Roadster. Once I have my Roadster, I will switch from puttering about in my car to zapping around in my car. Zap Cars had a reason for choosing that name, even though, like the so-called "Delicious" apple, the name is grossly misleading.

[bolosky]

A few days ago I spent the day lapping at a racetrack. ( Go-kart track, 0.9 miles, 18 turns, my max speed was about 74mph )

I was at the same event as Rich, and I also have an early 2.0 non-sport. I did something very similar to him, except that I drove and charged in standard mode, I didn't use performance mode at all.

My motor was hitting overtemp at 139C rather than 147C, so we can assume the difference is the extra room that you get out of standard mode. It seemed to cool pretty fast to around 60C and then plateau. My battery typically would warm up to ~33C and then cool back down into the high 20s by the time I was ready to go back out on the track.

The hottest that the battery got during the day was 40C. This happened not at the track, but on the drive home. I drove a fairly long distance between finishing at the track and getting home. By the time I made it home, my battery was down to about 20% in standard mode. The last leg of the drive is on 70mph freeway (meaning I went about 80). The battery heated up to 40C, a good bit warmer than it ever got on the track. I can only assume that this was because the lower state of charge combined with the current draw to drive pretty quickly for a few miles resulted in a lot of internal heating.

[richkae]

Bill, I'm not sure what the temperature threshold was that limited power due to overtemp of the motor. It could have been the same as yours. I tried to finish the lap I was on as fast as I could so the temperature kept going up and the 147C I reported was the peak.

[smorgasbord]

... 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).
...
So the roadster battery doesn't like to be rode hard and put away wet 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!

Scott, I just had an email exchange with my Customer Advocate, who said that there is no temperature difference behavior when plugging the Roadster in versus letting it sit. The only difference is that if it can, the car will use line power instead of battery power to heat/cool the battery. He told me I would do no damage by having the car wait many hours for the cheap power. They just don't want it unplugged for long periods of time. Thus, I believe that if you park the car with the battery temp at 40C, the cooling system will engage whether or not the Roadster is plugged in and getting power.

Can you explain what differences in battery temps you've observed plugging the Roadster in versus not? Could this be something they've improved on later models/firmware?