Model X

New to Model X- Battery Overheating from Supercharging?

Hey everyone, first I'd like to thank you all for all the valuable discussions on this forum. I've been lurking for a long time and finally pulled the trigger. Many questions I've had already were easily answered by reviewing this forum. Sorry that my first post is a bit of a downer and super long!

A little background: I purchased a new-to-me 2016 MX P90D with 28k miles this week. We've been driving it around town in the Phoenix area with very hot temperatures all week with no issues. I even got lucky with the email alerts on the Tesla Wall Charger being back in stock and installed it in our garage. We've been using this to charge the car so far.

Today we took our first road trip driving about 100 miles north through the mountains on our way to Flagstaff before our first stop at a Supercharger. I noticed while charging the speed started at 96kW and quickly began degrading, eventually ending at 8kW by the end of the 40 minute recharge we needed. As soon as I pulled out I noticed a difference in acceleration. As I got to the entrance ramp on the highway, I realized I had so little power I couldn't get the car to accelerate over 40 mph and had to pull over. I also noticed a yellow exclamation point on both the power meter and the regen meter, as well as the gray lines had turned to yellow dashes, however no other alerts showed up. I was able to slowly accelerate on to the highway up to a decent speed while my wife googled the issue. We found it was likely the battery was overheated. I drove very conservatively in the left lane, but with the grades we were traversing, it didn't help. After a few minutes the power decreased to the point I had to pull on to the shoulder with my hazards on, since there were no exits for miles. My wife called roadside assistance and they recommended I pull over and let the car set for 30 minutes (not fun in 100 degree heat). We followed their instructions and turned the car back on, discovering the meters had returned to their regular colors. We began traveling on our route, but as we hit some of the steeper grades (max of 6%) the yellow exclamation point returned and the meters began lighting up yellow again.

We made it in to Flagstaff and got to our hotel and let the car set and cool off. We got back in about an hour later and headed to a Supercharger while we grabbed lunch. As soon as I disconnected the Supercharger cable and got in the car, I noticed the yellow exclamation point was back and the power meter was nearly all yellow dashes. We drove back to the hotel (very gingerly) and called roadside assistance again (3rd time today). This time he had us perform resets on the MCU, instrument cluster, and a vehicle power cycle. We thought this could help, but also realized the common denominator was Supercharging, so we drove back over to try it out.... No luck. As soon as I unhooked the cable, I got the same alerts. I was out of options as this point and our trip was ruined, so Tesla is towing it to the service center in Tempe.

I've been searching all over the internet for similar situations, but have found very few that match our circumstances. I hope the service center will be able to diagnose the issue, but all 3 R.A. reps we spoke to seemed dumbfounded. I wanted to see if any forum members have had this issue.

Comments

  • Something is clearly wrong. One guess is the HVAC unit is underperforming, perhaps low on refrigerant. I've never heard of "hot" batteries occurring where it limits the performance in any noticeable way, except perhaps on the race track under extreme conditions. Driving in 120F is not considered extreme.

    First, it is normal for the Supercharger to taper it's charge as it gets near full. This guide will help you understand Supercharging and the taper curves:
    https://teslatap.com/articles/supercharger-superguide/

    The yellow dashes on the negative side of the energy graph indicate regen is limited. This occurs in cold weather before the battery warms up and will occur if you charge to 100% SOC. Generally, most owners only charge to 80-90% unless it is really needed. By not charging to 100% SOC, you avoid limited regen. Also, as you may have found out, it gets very slow to charge from 90% to 100% at a Supercharger to protect the battery pack. Limited regen has zero effect on acceleration.

    I suggest you schedule a service visit. It's doesn't sound like an emergency, as the vehicle will not let the batteries get into a condition that will harm them. But I'd avoid long trips until the issue is resolved.
  • > @"TeslaTap.com" said:
    > Something is clearly wrong. One guess is the HVAC unit is underperforming, perhaps low on refrigerant. I've never heard of "hot" batteries occurring where it limits the performance in any noticeable way, except perhaps on the race track under extreme conditions. Driving in 120F is not considered extreme.
    >
    > First, it is normal for the Supercharger to taper it's charge as it gets near full. This guide will help you understand Supercharging and the taper curves:
    > https://teslatap.com/articles/supercharger-superguide/
    >
    > The yellow dashes on the negative side of the energy graph indicate regen is limited. This occurs in cold weather before the battery warms up and will occur if you charge to 100% SOC. Generally, most owners only charge to 80-90% unless it is really needed. By not charging to 100% SOC, you avoid limited regen. Also, as you may have found out, it gets very slow to charge from 90% to 100% at a Supercharger to protect the battery pack. Limited regen has zero effect on acceleration.
    >
    > I suggest you schedule a service visit. It's doesn't sound like an emergency, as the vehicle will not let the batteries get into a condition that will harm them. But I'd avoid long trips until the issue is resolved.

    Thanks so much for your input. Good news is the customer service has been fantastic and the car is already towed back to the Service Center. We'll wait and see what comes of it.
  • Please post the result here.

    One idea is that you were using Range mode which lets the battery become hotter before cooling starts.

    Did you get proper cooling inside the car?

    An emergency solution when this occurs could be to switch off the A/C inside the car, and so let all available power go to cooling the battery. It's similar with an ICE that overheats - the solution then is to roll down the windows and put on max heat and max fan in the car to help cool the engine. Works like a charm :)
  • @Daniel - I think you understand, but for others - don't turn on the heat in an EV to reduce cooling load. It works in an ICE, but an EV is quite different. On a hot day in an EV, the heat will not hurt anything other than reducing range and making everyone really uncomfortable!
  • I live in Phoenix and have done that drive and used that super charger quite a bit. Love the car during the summer because of the cabin overheat protection and how quick it cools. I am sure they will get it sorted and once they do you will love it with our heat. Just wanted to let you know how well the cars can perform in our summer. I had a 2013 model S and now a 19 X.
  • Figured I'd check in and share how my situation played out. It turns out according to Tesla this was a pretty rare event and it was finally determined the HV battery pack needed replacement. Unfortunately, it took WAY longer than I think it should've (nearly 3 weeks), while they waited on engineering to agree with the recommended repair (I kind of understand the extra validation with the cost of this repair, plus at one point I was told my original Service Advisor suddenly was no longer employed there.....).

    It was frustrating to only have it for 3 days, then have it in the shop for 3 weeks, but at the end of the day I got a brand new HV pack at no additional cost to me, and I'm thrilled! Also, the passenger exterior mirror wasn't folding correctly, so I asked them to give me a quote on that repair (I'm out of bumper to bumper due to time) while they were just sitting on the car. They determined it needed to be replaced at nearly $1k. Without prompting, the Tempe service center offered to cover the repair at their cost. They definitely worked hard to make a bad situation better. Oh yeah, plus they put us in a Model S loaner too. A 2012 with 76k that was beat to hell, but a loaner none the less.

    Thanks for all of your insight and feedback. I'm really enjoying the community and funny enough, even more bought in on Tesla than I was previously. Thanks!
  • @Texla - Thanks for coming back and telling us what was done. Glad they took care of you. This was definitely a strange one. I can't remember anyone else having an issue like this caused by the battery pack. I expect they'll ship it back to engineering to take a look at exactly what went wrong inside the pack.
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