Supercharging Hypothetical #2 -- Abusive or not?

[stevezzzz]

Things have changed from the old days: "Never pass up a charging opportunity" used to be the mantra.

 

[dhanson865]

Ernie has relatively low energy consumption needs. He is able to charge his car every third day when he does his normal driving. He typically charges to 90% and recharges when he gets around 20%. He has a 40 amp charging station at home and lives close to a supercharger that is located in a busy shopping center that has both restaurants and stores that Ernie uses frequently. Ernie has never seen the supercharger full, in fact, he has never seen more than one other car charging when he is there. He is always careful to move his car when charging completes and never uses a charger if there are already 2 or more of the 8 stalls occupied.

Which of the following scenarios do you think are abusive and which do you think are acceptable? Feel free to explain your position.

A> Ernie normally does not use the superchargers even when he is shopping or dining nearby, unless he is very close to his 20% cut-off

B> Ernie makes no special effort to go to the shopping center, but anytime he is there he plugs in and tops off his car to 90%. This results in him charging at the supercharger once or twice a week.

C> Ernie tries to schedule his life so that he eats or shops whenever his car nears 20% at the mall, and he finds that he can do this three times a week on average and very rarely needs to charge at home.

A, I'd say Ernie should charge to 50% any time he is below 50% since it is available and very low SOC is bad for the battery and usability. He'd be stupid to park near the supercharger but not charge up when low.

B, I'd say Ernie should stop his charge at a lower percentage anywhere between 50% and 90%. Take advantage of it while he is there but don't stay longer for the charge. He should do so ready to get his car moved the minute it gets charged enough for his purpose. Still not abusive in the least if he doesn't sit around doing nothing past taper.

C, I'd say he shouldn't be letting it get down to 20% and he shouldn't be charging up to 90%. Bad for his car and with the kwh supercharged vs home this one is on the abusive side. Change this so that he charges with 12a 120V at home or a 6a or higher L2 on any sort of socket at home and charges as much as possible to 80% when at the supercharger and I'd give him a pass and no longer see it as abusive.

C1 abusive that he stays so far past taper. If he is going to be there 3 times a week he can afford to leave sooner each time he charges and charge more often. Pick a stopping point between 50 and 70% if he can get away with it, push it to 75 or 80% if he has to but avoid sitting there too long each time, split it up over more days.

C2 abusive that he doesn't plug in at home enough to let the car balance and get a slight charge (I'm OK with him gaming this by intentionally lowering the amps on the EVSE, using a lower power EVSE, using an openEVSE with the amps lowered to 6 or whatever he chooses, lowering the amps from the center display on his Model S)

So with very minor modifications I'd choose D, but as is I'm on the C spot.

 

[KJD]

Things have changed from the old days: "Never pass up a charging opportunity" used to be the mantra.

Back in the old days when we drove lead acid conversions with a 50 mile range I did what you said. Those days are long gone and I am grateful for that.

The superchargers where built to enable long range travel and that is when they should be used. Other than that you should charge at home, at night when the batteries are cool and the load on the grid is light. Good for the batteries and good for the grid.

 

[Six]

It is abusive not because it costs Tesla a few dollars but because long distance travelers could be stuck while someone who could charge at homes shops for who knows how long.

All just my opinion. Why would you inconvenience other Tesla owners who have no choice, just to save a dollar or five or ten? I have no answer that works for me. I do recognize that people have different opinions.

 

[ItsNotAboutTheMoney]

I voted all abusive. (Not that I like the term abusive, but I understand what it meant.)

I don't park in disabled parking spots*. I wouldn't opportunity charge at Superchargers.

Now, if Ernie lived in Central Maine and had driven his S60 down to the Maine Mall in South Portland during late fall, and Ernie wasn't sure whether he'd make it home, then sure, Ernie, charge at the new** Maine Mall Supercharger.

* Except when carrying a disabled passenger, of course.
** and completely imaginary

 

[LetsGoFast]

So this is saying, sort of sideways, that mileage is directly related to battery degradation. Yet the studies I have seen show that battery degradation is related to TIME, not mileage, not "charge cycles".

I have 80,000 miles on my 3 year old Model S. It has about 8% degradation, the same as most other Model Ses this old.

It also seems apparent that it is the hot charges, ie: going to 100% and letting it sit, or driving 80 on the freeway on a hot day and pulling into a supercharger for a full charge, that cause degradation. Is that wrong?

I charge my battery at night at about 30 amps. I don't care how many cycles I have made (which correspond to 265 miles more or less for 85 kWh). I am not sure at all that it is charge cycles, but outright abuse. Batteries like to be "room temp". Outside of that, you have degradation. Even if Tesla tries to AC or heat the battery pack, I feel there are times that the conditioning can't keep up.

There are a number of factors, some of which we don't know about because Tesla has tweaked the battery design. High charge levels at high temps are absolutely certain to be the worst case scenario. 100% charge is the worst, but 90% isn't a magic number. A hot battery at 80% is almost certain to experience less degradation than a hot battery at 90%. Testing of other batteries shows that depth of discharge affects battery life in a non-linear way. A battery that is only discharged 50% of its capacity will last for more than twice as many cycles as a battery that is discharged 100%. It is pretty clear that a battery that cycles from 70-30% will degrade less than a battery that cycles from 90-50% or from 50-10%.

Its also pretty clear that a car that lives in northern climes will have longer battery life than one that lives near the equator. Tesla cools the battery to a point that they judge limits degradation to a manageable level but it is almost certain that the battery would fare better if it was colder. None of us know the degree to which this is the case, however.

- - - Updated - - -

It is abusive not because it costs Tesla a few dollars but because long distance travelers could be stuck while someone who could charge at homes shops for who knows how long.

All just my opinion. Why would you inconvenience other Tesla owners who have no choice, just to save a dollar or five or ten? I have no answer that works for me. I do recognize that people have different opinions.

I agree with you completely that if one's charging behavior affects other owners one should absolutely minimize their supercharger time. That's why I specified Ernie only charges when there are 6 or more open stalls, to eliminate that particular problem.

Thanks to everyone who is explaining their thinking. I find it quite fascinating.

 

[scaesare]

For him to have done something wrong or abusive, there has to be a party that is harmed. Tesla being required to pay for the electricity doesn't meet that burden for me.

If Tesla did not intend, nor budget, for offsetting customer's daily charging costs, then they indeed are harmed, and it's abusing the intent of the system.

 

[LetsGoFast]

If Tesla did not intend, nor budget, for offsetting customer's daily charging costs, then they indeed are harmed, and it's abusing the intent of the system.

I guess what I really meant was that if Tesla failed to accurately estimate the average consumption of electricity in their pricing model, I'm not terribly concerned about that personally. Obviously enough, half of the users are going to be above the median consumption so it isn't inheriently abusive to be "above average." I'd agree that it is abuse when we talk about a taxi charging several times per day just based on the effect on Tesla, but I wouldn't agree for most ordinary consumers.

I know a local guy that charges 100% of the time at Superchargers because he doesn't have access to an outlet in his condo or at his workplace. He is clearly an outlier in terms of his expense to Tesla, but I don't find anything wrong with his behavior at all and my sense is that neither do most of us. Tesla very much pitched this approach as a viable one for him when he bought the car and I assume their pricing model included some number of this type of user. If you assert that consuming more electrons that Tesla budgeted for is abusive, then you can't really distinguish the two cases.

The apparent conclusion I draw is that for most of us, it is only abusive (or wrong, if you prefer) to rely on superchargers for the exclusive reason of saving money when you have a viable home charging option.

52% of us (at the time I write this) are OK with Ernie charging up anytime he happens to be at the mall. I'm obsessed with data, so I think this is going to require me to make a follow-up poll.

 

[scaesare]

I guess what I really meant was that if Tesla failed to accurately estimate the average consumption of electricity in their pricing model, I'm not terribly concerned about that personally.

Which is why intent is important. If they intend Superchargers to enable long distance travel, and/or allow for apartment dwelling, then their model will reflect that. If everybody ignores the intent and instead uses them to avoid paying for their own charging needs, then I don't think that's Tesla failing "to accurately estimate the average consumption of electricity in their pricing model".

What's more, electricity isn't the only possible damage done. Congestion, and thus overall # of supercharger sites that need to be built out, could be impacted.

The apparent conclusion I draw is that for most of us, it is only abusive (or wrong, if you prefer) to rely on superchargers for the exclusive reason of saving money when you have a viable home charging option.

Agreed. And that implies there's intent involved.

(and incidentally, I don't count the "I won't bother to go through the time and expense to install my home charging setup" premise as being "unable to reasonably provide for your own charging". That's just lazy or cheap.)

 

[Electricfan]

I chose B & C.

Ernie paid about 2K for SC when he bought the car, and its fair for him to get that back. But if he drives the car 2 years getting 3 charges there per week and picking up 60kwh each time, he's going to get his money back and then start making a profit.