Concerned about battery degradation and "vampire" charging in Arizona during summer.

[dsm363]

First of all, I am on GM-Volt. Second, no one in that thread really talked about range loss when temps are 115 or so. And I've lived in TX previously where it would hit the 100s. But 115 is a big difference. The spot at work isn't covered, so yes, the car does stay baking in the sun. And yes, it is a lot of shorter trips (I rarely drive 40+ miles in one stretch in my normal driving of the Volt). Plus factor in that I do have a yong toddler, so I really do have to use the comfort mode AC. If it was just me, I could use comfort a short while, then switch to econ. But with the toddler in the back, I pretty much need to keep the AC on comfort mode the full time.

Anyways, to get back on topic, I sent a message to my Roadster friend to ask if I can post his graphs. Hes on vacation and will be back on Monday, so I dont expect a response til then.

Since you only drive 40 miles on a stretch and you plug in at work, you shouldn't have anything to worry about it seems. The car will always work to keep the battery pack in the safe range, even when it is not plugged in. What kind of outlet do you have at work to charge? The mobile app will take car of pre-conditioning the cabin. You will be able to blast your AC since you trips are shorter and not worry about the range as well.

 

[BilliardsGuy]

Being an Phoenician, I am also wondering about the effects of our lovely summer heat on the MS battery and range. Seems like more data is needed. (Wish I had been an engineer at times like this.)

Rem: Are you an owner now? But regarding your comment, I am an engineer (actually, a physicist, but my career was more like an EE) but I'm not a battery expert. I hope and expect that Tesla has really good, deep insight into the existing battery chemistry and capabilities and when we are told they tested the Tesla in "Death Valley" or similar consitions, I hope that means the results were satisfactory!!

I recently came across some articles that I found quite interesting regarding Tesla batteries and plans in general and long distance travel capabilities which I think all would be interested in. They are at

Will Tesla Disrupt? - Seeking Alpha

and

Has Tesla Solved The Road Trip Problem? - Seeking Alpha

The anlaysis given is very interesting, but does not make use of any insider Tesla info as far as I know.

This time next year we should know a little more about the Model S in AZ from some owners.

 

[jomo25]

Since you only drive 40 miles on a stretch and you plug in at work, you shouldn't have anything to worry about it seems. The car will always work to keep the battery pack in the safe range, even when it is not plugged in. What kind of outlet do you have at work to charge? The mobile app will take car of pre-conditioning the cabin. You will be able to blast your AC since you trips are shorter and not worry about the range as well.

Yes, having the Volt for more than a year, I have a very good feel for our driving style and habit as it relates to range. However, I asked the question of my friend because I wanted to know his experience as it would impact trips we take within AZ like Sedona, Flagstaff, Tucson, Pinetop, Payson. I know if I want to go to Vegas, LA, or SD, it will involve at least one stop regardless of battery pack size. However, I would like to be able to go to most of the AZ spots with one or no stops. So, it's the deciding factor between going with the 85 or 60.

Also, I asked him about the impact of elevation changes. I.e. PHX is at about 1000 ft. Flagstaff is about 7000 ft, pretty much all climb. So, of course there's an impact on consumption. He said his experience has been fairly close to the theoretical purely based on weight of vehicle. I.e. So figure out how much kWh you'd need if the trip was flat, then add/subtract the amount to account for the elevation change.

E.g. Assume it takes 40 kWh to go from PHX to Flagstaff (I'm just using the figure for demo purposes). Then factoring a 5000 lb vehicle doing 6000 ft of climb, it's about 11 kWh extra. So, it would be 51 kWh total. (Conversely the trip back might only take 29 kWh since its all descent.) He said it's pretty linear based on the weight. (It's a reason I was hoping the 60 would come in at lower weight than the 85.)

I'm probably going with the 60. I don't make those trips often (max 2 per year), and there does appear to be quite a few RV sites with 50A hookups all along the AZ roadways to any of those places above, so I could charge if in a pinch. Plus, as my friend did say, how many rental cars could I get for $8500 for such trips - quite a few.

 

[dsm363]

I'm probably going with the 60. I don't make those trips often (max 2 per year), and there does appear to be quite a few RV sites with 50A hookups all along the AZ roadways to any of those places above, so I could charge if in a pinch. Plus, as my friend did say, how many rental cars could I get for $8500 for such trips - quite a few.

Good point. The 60 kWh with Supercharging might be the way to go if the 85 kWh didn't cover all of your possible trips. I'm sure a few other Arizona owners have taken these trips in their cars (not in summer of course) who might be able to provide more feedback on battery pack choice. Can check in the regional forum

Mountain/Southwest

 

[napabill]

Thanks for the replies to my questions.

And I had not visited the "goelectric" tab recently with the estimates of range for various conditions - that was very interesting. I note that the dials only allowed ambient temperatures up to 90 degrees - what about 115-120 degrees! I drive from the Phoenix area to San Diego quite a lot and I was hoping for a SuperCharger to be placed in Yuma in which case I would be able to get there no problem - I thought!! But using the dials with a 90 degree ambient and with the A/C going and driving at 65 mph the range drops to 247 miles. But what if the ambient temperature is 115, with the A/C going (are you kidding!), I have a panoramic roof and I'm driving at 80 - 85 mph (my and everyone else's average speed on that stretch) will I even be able to get to Yuma? And then I have to recharge to go another longer but cooler stretch but that requires virtually a full recharge. Will the Tesla allow a full recharge - not just another 60 miles, but over 200 miles - in one SuperCharging session? Maybe the answer here is that the Tesla is not the way to go for long distance driving in hot climates. Most of my driving is actually local driving so not being able to do a Phoenix to San Diego trip in the dead of summer is not really a killer - I will just use an ICE for that type of trip, but it is a strike against my purchasing a Tesla for sure.

I'm not an expert on LiIon batteries, but I have researched data on them to some extent and batteries do degrade faster at high storage temperatures and degrade if overheated when charging. I know Tesla says they have engineered this extensively and am hopeful they have verified their system in "Death Valley" or wherever.

But I asked this question (effects of high ambient temperatures) to Bryan Bailin at Tesla Corporate and he informed me then about the active cooling system that would run and keep the battery temperature in an "optimum" range, and he specifically cited a temperature of 75 degrees. Now maybe that wasn't the exact design target, but if it is anything like that it will require battery resources on a 24/7 basis when minimum tempratures are 90 degrees or so and even more when exposed to direct sunlight parked on black asphalt - and even if the car shades the battery, the car itself gets really hot and the "ambient" inside the car is far above the ambient outside the car if left for some time.

I wish Tesla engineering would jump in on topics like this and tell us the correct info. I'd like to know the basics of the battery temperature control algorithm and also to know the power drain figures under various ambient temperatures for both the battery temperature control and for human climate control. Inquiring minds want to know!!

Thanks for any other input - Tesla Corporate can jump in here any time to straighten me out on these issues.

You still pass through Yuma occasionally? I'm convinced there will be a SC site at the Yuma Palms Regional Center (I-8/Hwy 95). You might check it out next time through. Also, are you aware of any Yuma MS owners?

I leave for California from Tucson at the end of next week and I had great hopes for a new SC somewhere along the AZ/CA border. Still waiting.

 

[BilliardsGuy]

You still pass through Yuma occasionally? I'm convinced there will be a SC site at the Yuma Palms Regional Center (I-8/Hwy 95). You might check it out next time through. Also, are you aware of any Yuma MS owners?

I leave for California from Tucson at the end of next week and I had great hopes for a new SC somewhere along the AZ/CA border. Still waiting.

I'm still subscribed to this post because I am curious and interested but due to the lack of a SC station and the lack of an announced schedule, I decided against the purchase of a Tesla and have changed course. I am still rooting for Tesla and might get interested in a future version when long distance travel is more easily achieved.

 

[zdre]

From a picture I saw in another thread, the Model S battery's passive cooling target is 40C and the active cooling target is 55C. Not exactly sure what that means though. The heating target is 10C.