Etiquette Question: When is a Super Charger not a Super Charger?

[scaesare]

Well, maybe we should lobby Tesla to install a couple of Destination Chargers when they install Super Chargers at actual destinations. I'm not complaining about having to stop along the way to charge, but to delay getting to sleep and then having to wake up an hour earlier to finish charging before a 13 hour drive is not a good thing. I may have AP, but I still need to be awake when I drive (especially since the AP likes to swerve into Nevada's off ramps...)

While it may be hard to not think of them as chargers at your destination when they are in your motel parking lot, try thinking of them as a "nearby supercharger" that just happens to be in the parking lot. I've happened to charge at Superchargers in a hotel lot before as a stop on a road trip, but not actually staying at the motel.

But what if the supercharger in that town were instead near mall a mile down the street?

In that case, you'd STILL be delayed getting to sleep and have to get up early, as well as perhaps even delaying getting your family checked in to the hotel or loaded up in the car to leave. AND you likely have to stay with the car for each session, unless you wanted walk back and forth to the hotel.

In this case, you get to simply walk down to the parking lot, and then you can be back in the hotel doing other things during the charging sessions.

 

[Az_Rael]

So, the bigger question this scenario raises is why is Tesla installing Super Chargers at destinations, if they don't intend for them to be treated as a destination?

Sometimes destinations and supercharger routes correspond. I think hotels petition to get destination chargers (and pay for the power) so if they have a supercharger bank in their parking lot, they may think "why bother"?

Harris Ranch is a very large full service hotel with a very busy supercharger in its parking lot. There is not a destination charger there, but I am pretty sure any hotel guest who parked overnight at that supercharger would be awoken to a very large idle fee bill from Tesla and possibly nasty notes from other late night travelers. Obviously Harris Ranch is where it is to make the I5 network work, not as a destination charger. It just happens to be in a hotel parking lot.

 

[Sawyer8888]

Whether it is a destination charger or a supercharger or a supercharger that is a destination charger, it is like anything else that is shared by a community. When you're done with it, make every effort to make it available to others.

Do your best to plan around having to leave your car fully charged overnight in a space that someone else could potentially use.

 

[sdorn]

(1) You don't want to charge to 100% at night because leaving your vehicle at 100% for 6-7 hours overnight will severely impact your battery longevity.
(

Please share your source for the statement that leaving your vehicle at 100% SOC for 6-7 hours will severely impact your battery longevity. The studies I've read on degradation of lithium ion batteries when left at 100% charge were measured in periods of several consecutive months at constant temperatures of 50 degrees Celsius or more, not single occurrences of merely a few hours in normal temperatures.

 

[vandacca]

Please share your source for the statement that leaving your vehicle at 100% SOC for 6-7 hours will severely impact your battery longevity. The studies I've read on degradation of lithium ion batteries when left at 100% charge were measured in periods of several consecutive months at constant temperatures of 50 degrees Celsius or more, not single occurrences of merely a few hours in normal temperatures.

It's a well known fact that leaving battery at high temperature and high state of charge (SOC) is very harmful to the battery. If you're interested in the detailed statics (SOC/temperature/time), see Table 3. Note that the 40% charge column is loss after 1 year, but the 100% charge loss column is after only 3 months.

Unfortunately, there isn't a nice hourly loss of capacity table I could find, but we can extrapolate with the above information. But, the end result is the same. Keep a high SOC as minimal as possible and note that the degradation is cumulative. So, 1 hour at 100% is much better than 6 hours.

If you're interested to know why high SOC (and temperature) is bad, see Prof Dahn's (now doing research for Tesla) University of Waterloo talk. Basically, a Lithium precipitate forms around the cathode/anode that reduces the battery capacity.

 

[rhumbliner]

Well, maybe we should lobby Tesla to install a couple of Destination Chargers

It's not up to Tesla to install HPWC's, it's up to the property owner. Tesla's policy is to supply the equipment for free if the property owner supplies the space and the electricity. I carry a pack of HPWC brochures that explain this policy and hand them out to hotels, motels, and BnB's that I visit. So we should be lobbying destinations, not Tesla.

 

[Xenius]

@rhumbliner Did you create the HPWC brochures on your own? Would love to have something like this to hand out.

 

[rhumbliner]

@rhumbliner Did you create the HPWC brochures on your own? Would love to have something like this to hand out.

I called Tesla Sales: 650-681-5100. They mailed a packet of 20 brochures.

 

[Carl]

It's a well known fact that leaving battery at high temperature and high state of charge (SOC) is very harmful to the battery. If you're interested in the detailed statics (SOC/temperature/time), see Table 3. Note that the 40% charge column is loss after 1 year, but the 100% charge loss column is after only 3 months.

Unfortunately, there isn't a nice hourly loss of capacity table I could find, but we can extrapolate with the above information. But, the end result is the same. Keep a high SOC as minimal as possible and note that the degradation is cumulative. So, 1 hour at 100% is much better than 6 hours.

If you're interested to know why high SOC (and temperature) is bad, see Prof Dahn's (now doing research for Tesla) University of Waterloo talk. Basically, a Lithium precipitate forms around the cathode/anode that reduces the battery capacity.

I'm intrigued by this as well. I can't imagine a severe impact on range/battery life by what we're talking about, which is charging the car up to 100% at night a couple of times a year before or during a road trip (so this is definitely not about leaving the car on a 100% charge for a whole year without ever driving it). Also, findings from yesteryear (some graphs are from 2002!) are perhaps much less relevant today. I wonder if anyone can chime in with practical knowledge on how this works out with a Tesla, anno 2013-2017.

 

[sdorn]

It's a well known fact that leaving battery at high temperature and high state of charge (SOC) is very harmful to the battery. If you're interested in the detailed statics (SOC/temperature/time), see Table 3. Note that the 40% charge column is loss after 1 year, but the 100% charge loss column is after only 3 months.

Unfortunately, there isn't a nice hourly loss of capacity table I could find, but we can extrapolate with the above information. But, the end result is the same. Keep a high SOC as minimal as possible and note that the degradation is cumulative. So, 1 hour at 100% is much better than 6 hours.

If you're interested to know why high SOC (and temperature) is bad, see Prof Dahn's (now doing research for Tesla) University of Waterloo talk. Basically, a Lithium precipitate forms around the cathode/anode that reduces the battery capacity.

You've proven my point by linking to one of the studies I was referring to in my post. They all assume storage at 100% SOC for several consecutive months at a high ambient temperature. Show me a study that shows degradation at normal temperatures over short periods of time (i.e. < 24 hours). You indicated in your original post that over a period of only 6-7 hours at 100% SOC the battery's longevity would be "severely impacted". To make such a statement surely you have some actual relevant information to back it up?

 

[vandacca]

You've proven my point by linking to one of the studies I was referring to in my post. They all assume storage at 100% SOC for several consecutive months at a high ambient temperature. Show me a study that shows degradation at normal room temperature over short periods of time (i.e. < 24 hours).

Did you actually follow my link and read the article? Table 3 lists temperatures between 0ºC-60ºC (32ºF-140ºF). I'd consider 25ºC as ambient temperature. At 25ºC, it states that after 3 months, 20% of battery capacity is lost (which is significant in my opinion). Assuming a linear degradation, that's roughly, 0.01% per hour.

1 hour at 100% = 0.01% degradation
6 hours at 100% = 0.06% degradation

It's cumulative, so it's best to minimize time spent at 100%. I guess I don't find your point meaningful, since I personally try to reduce degradation whenever possible. I plan to keep my vehicle for over 15 years, so getting into the habit of minimizing degradation will pay off over the life of my vehicle.

I guess if you're leasing your vehicle and don't plan to keep it beyond the initial 4 years, then yeah, go nuts and leave it at 100% at all times. At some point someone may take notice and ding you for premature battery wear, but maybe not.

 

[dprisoner]

But what if the supercharger in that town were instead near mall a mile down the street?

In that case, you'd STILL be delayed getting to sleep and have to get up early, as well as perhaps even delaying getting your family checked in to the hotel or loaded up in the car to leave. AND you likely have to stay with the car for each session, unless you wanted walk back and forth to the hotel.

In this case, you get to simply walk down to the parking lot, and then you can be back in the hotel doing other things during the charging sessions.

No, I'd choose my hotel based on charging amenities. Hotels that have a Super Charger were ideal, because I wouldn't have to worry about whether the connector was compatible with my car. On our return through Reno we stayed at another hotel (because the Atlantis was booked the Sunday night of Memorial Day weekend) with one spot that had a 40a Tesla charger and another charger on a pole and that was perfectly fine. I guess in future I'll just have to take a chance as to what kind of charger a hotel has and not patronize the ones with Super Chargers. Being fully rested for a long drive is more important to me.

 

[vandacca]

I'm intrigued by this as well. I can't imagine a severe impact on range/battery life by what we're talking about, which is charging the car up to 100% at night a couple of times a year before or during a road trip (so this is definitely not about leaving the car on a 100% charge for a whole year without ever driving it). Also, findings from yesteryear (some graphs are from 2002!) are perhaps much less relevant today. I wonder if anyone can chime in with practical knowledge on how this works out with a Tesla, anno 2013-2017.

The analysis was done on generic Lithium Ion batteries available at that time. Tesla uses their own proprietary formula (as do all other battery manufactures). Battery chemistry doesn't change or improve that quickly, so that 2010 article (last updated this month) is still mostly relevant today. Exact numbers are hard to come-by because there are so many variables involved (charge rate, discharge rate, temperature, battery management algorithm, chemistry, time, anode/cathode material, etc.).

The point of that article is to stress good habits to prolonging battery health, not for predicting how long a battery will last.

 

[Carl]

The analysis was done on generic Lithium Ion batteries available at that time. Tesla uses their own proprietary formula (as do all other battery manufactures). Battery chemistry doesn't change or improve that quickly, so that 2010 article (last updated this month) is still mostly relevant today. Exact numbers are hard to come-by because there are so many variables involved (charge rate, discharge rate, temperature, battery management algorithm, chemistry, time, anode/cathode material, etc.).

The point of that article is to stress good habits to prolonging battery health, not for predicting how long a battery will last.

I understand that, and for the avoidance of doubt, I'm also sure you (and the linked article) are right! I just wonder how "severely" you are right, in practice (i.e. if it is something we should in practice worry about, if we're only doing this 'bad' thing a couple of times per year and only for 6-7 hours each time).

 

[TexasEV]

No, I'd choose my hotel based on charging amenities. Hotels that have a Super Charger were ideal, because I wouldn't have to worry about whether the connector was compatible with my car. On our return through Reno we stayed at another hotel (because the Atlantis was booked the Sunday night of Memorial Day weekend) with one spot that had a 40a Tesla charger and another charger on a pole and that was perfectly fine. I guess in future I'll just have to take a chance as to what kind of charger a hotel has and not patronize the ones with Super Chargers. Being fully rested for a long drive is more important to me.

You don't have to worry about whether a connector at a hotel is compatable with your Model X. If it's not a HPWC it will be a J1772 and all cars are delivered with that adapter. Even a 30A J1772 will give you a reasonable charge overnight, at least 150 miles in 10 hours. But I still don't understand why you think superchargers at hotels are a problem. Charge up to 90% when you arrive (or even less if you arrive late and don't want to wait that long for it), move the car to a nearby space, and charge the remainder while you are getting ready in the morning and having breakfast.

 

[DOCAL]

Hotels that have a Super Charger were ideal, because I wouldn't have to worry about whether the connector was compatible with my car.

Which hotel have you seen with a connector you couldn't use? I've never seen hotels with anything besides Tesla or J1772.

I always look at PlugShare when considering hotels to stay at, that will solve your problem anyway.

 

[vandacca]

I understand that, and for the avoidance of doubt, I'm also sure you (and the linked article) are right! I just wonder how "severely" you are right, in practice (i.e. if it is something we should in practice worry about, if we're only doing this 'bad' thing a couple of times per year and only for 6-7 hours each time).

Right, "severely" is a rather subjective term. If I accidently left the vehicle plugged in at 100% for 6-7 hours, I wouldn't really fret too much over it. But for me, intentionally doing that, even a few times a year seems wrong on many levels:
(a) It does do unnecessary harm to your battery (even though it's less than 1%, it's still unnecessary harm that will add up)
(b) It is bad etiquette at shared charging locations, which is how this whole topic came about.
(c) It is a bad habit to get into

It's your vehicle, and as long as you're not impacting other EV drivers, then you can take all the risks you feel comfortable taking.

Me, I'm a little OCD. After getting home from a long trip with the battery limit set to 100%, I forgot to change it back to 90% before going to bed. At 1am, I awoke realizing my mistake and according to the phone app, it had just completed charging to 100%. So, I did what every OCD Tesla nut would do and get out of bed and drive around for 20 minutes in my PJs to get the charge back down to ~92%. I could have waited till morning, but I love driving my car that much. And I'm trying to develop good habits for a vehicle I plan to keep for over 15 years.

I'm waiting for solid-state batteries, where keeping the battery at 100% charge is a non-issue.

 

[HankLloydRight]

In that case, you'd STILL be delayed getting to sleep and have to get up early, as well as perhaps even delaying getting your family checked in to the hotel or loaded up in the car to leave. AND you likely have to stay with the car for each session, unless you wanted walk back and forth to the hotel.

I just wanted to chime in on this issue. I think the normal thinking/convention is to find an overnight charging spot at/near your hotel.

But for the reasons above (which happened to me *once*), the plan I now use on all long road trips (and I've taken many), is that I plan my hotel stops almost equidistant between Supercharger stops.

This way, towards the end of the day, I'll pull in and charge for 30 minutes or so or whatever is needed to get to the next supercharger (the next day). Stop at the hotel somewhere along the highway and just park there overnight. Check-in, go to sleep.

The next morning, I'll get up and out on the early-ish side, drive 30-40 minutes to the next SC, and then stop and have a leisurely breakfast and have an almost full charge by the time I'm done breakfast. Then I'm ready for that day's travels with a nearly full charge. Lather, rinse, repeat.

Using this method, I never have to worry about finding a hotel near a supercharger, or a hotel with local level 2 charging. I can just find a nice, affordable hotel along my route, and just use the Superchargers as I would normally be doing anyway.

 

[sdorn]

Did you actually follow my link and read the article? Table 3 lists temperatures between 0ºC-60ºC (32ºF-140ºF). I'd consider 25ºC as ambient temperature. At 25ºC, it states that after 3 months, 20% of battery capacity is lost (which is significant in my opinion). Assuming a linear degradation, that's roughly, 0.01% per hour.

1 hour at 100% = 0.01% degradation
6 hours at 100% = 0.06% degradation

It's cumulative, so it's best to minimize time spent at 100%. I guess I don't find your point meaningful, since I personally try to reduce degradation whenever possible. I plan to keep my vehicle for over 15 years, so getting into the habit of minimizing degradation will pay off over the life of my vehicle.

I guess if you're leasing your vehicle and don't plan to keep it beyond the initial 4 years, then yeah, go nuts and leave it at 100% at all times. At some point someone may take notice and ding you for premature battery wear, but maybe not.

Yes, I did read the article and saw the table.

It is not clear that the time period for the entire 100% column is 3 months as the table is labeled as showing degradation over an entire year. The parenthetical regarding three months appears to only apply to the reading at 60 degrees Celsius.

Also, a more recent study published in 2016 shows that at a 100% SOC an 18650 lithium ion cell (like the ones used in a Tesla) only loses about 5% capacity over a 9-10 month period at 25 degrees Celsius. See figure 2 (also pasted below).

 

[Sawyer8888]

(i.e. if it is something we should in practice worry about, if we're only doing this 'bad' thing a couple of times per year and only for 6-7 hours each time).

I may have done this "bad thing" a few times within the first two months of ownership (not at a Supercharger or other public charger). This may explain why I was already short on mileage before I reached 3000 miles - albeit, only by a fraction. But still, so early into ownership?

60 KwH (software limited 75 - still), max was 210 miles when new in April.

• 90% is now no higher than 188 (89.5%)
• 100% is now no higher than 208 (99%)

Just to stay on the topic of etiquette, do not leave your fully-charged vehicle at any public charging station for any length of time if you can help it. Doing so is poor etiquette.