Supercharger Tier 1 vs Tier 2

[a.void]

I just Supercharged for the first time today, and I'm trying to understand how this monitor this better the next time.

I plugged in with 105 miles and I unplugged at 193 miles for a total of 85 miles.

My receipt shows Tier 1 charging for 23 minutes and Tier 2 charging for 2 minutes.

Tier 1 charging is up to 60 kw and Tier 2 is anything over 60 kw.
If our LR battery is about 80kw, then I would expect Tier 2 to kick in around 232 miles or 75% (60/ 80) of 310 mile range.
I understand the mileage isn't a perfect representation of kw usage, but that's a pretty big gap that it charged me Tier 2 around 185 miles. Tier 2 is double rate, so I want to minimize whenever possible.

Thoughts or input?

 

[israndy]

If it is charging at > 60kW for 1 minute, that's at least 1kWh for 22¢ [in Ohio, better than my 26¢/kWh in California.]. I wonder if they picked that rate so the math was easy. The slower it charges the more it costs to charge, so the sweet spot is that empty battery or that battery that is charging at just under 60kW. Filling the battery is probably cheaper in California as there isn't that per minute towards the end.

The LR pack is 74kWh's. Someone should do an analysis of what the limit should be set to in the per-minute States for each Model so you don't lose money as it dribbles in that last bit of energy. @bensullins maybe. That math is over my head, I would just use anecdotal evidence and hope I got it right.

-Randy

 

[NOLA_Mike]

@a.void Google and look up the difference between kW and kWh. Your battery has a capacity of about 75 kWh but can take a charge at a rate over 100 kW.

 

[jdcollins5]

I just Supercharged for the first time today, and I'm trying to understand how this monitor this better the next time.

I plugged in with 105 miles and I unplugged at 193 miles for a total of 85 miles.

My receipt shows Tier 1 charging for 23 minutes and Tier 2 charging for 2 minutes.

Tier 1 charging is up to 60 kw and Tier 2 is anything over 60 kw.
If our LR battery is about 80kw, then I would expect Tier 2 to kick in around 232 miles or 75% (60/ 80) of 310 mile range.
I understand the mileage isn't a perfect representation of kw usage, but that's a pretty big gap that it charged me Tier 2 around 185 miles. Tier 2 is double rate, so I want to minimize whenever possible.

Thoughts or input?

The Supercharger starts out at the highest charging rate and then begins to taper down as the battery gets closer to full charge. The intent is to charge as quickly as possible, not to save money at a slower charging rate. If you want to charge at the slower, cheaper rate, go somewhere other than a Supercharger.

 

[a.void]

If it is charging at > 60kW for 1 minute, that's at least 1kWh for 22¢ [in Ohio, better than my 26¢/kWh in California.]. I wonder if they picked that rate so the math was easy. The slower it charges the more it costs to charge, so the sweet spot is that empty battery or that battery that is charging at just under 60kW. Filling the battery is probably cheaper in California as there isn't that per minute towards the end.

The LR pack is 74kWh's. Someone should do an analysis of what the limit should be set to in the per-minute States for each Model so you don't lose money as it dribbles in that last bit of energy. @bensullins maybe. That math is over my head, I would just use anecdotal evidence and hope I got it right.

-Randy

I thought our battery was 78-80 kwh, but regardless.

The point is it flipped me to Tier 2 at around 60% full battery (180 miles on the battery meter) Tesla quotes Tier 2 at 60 kwh which is closer to 75-80% full battery (230+ miles on the battery meter).

Looks like BS to me

 

[zswilliams]

Hello!

To be clear,

Kwh = capacity. Kw = power.

If the car is charging at a rate of >60Kw (power coming into the car) then you are charged at the tier 2 rate.
If the car is charging at a rate of <60Kw, then you are charged at the Tier 1 rate.

The rate you are charges does not have to do with the size of your battery (well it does, but not in terms of raw numbers).

The more full your battery is, the less power your car will accept, and the lower the charging tier you should be in.

It's possible that you started in Tier 1 due to multiple cars charging on the same supercharger (1 charger powers 2 charging stalls).
Then, once that car tapered off, it allowed your car to draw more than 60kw from the charger, and then it flipped you to tier 2.

In short, the tier is determined by the charing rate, not the battery capacity level.

 

[tecis]

Tier 2 is double rate, so I want to minimize whenever possible.

Thoughts or input?

There is really nothing you can do.

It all depends on 3 factors:

Battery state of charge once you plug in

type of supercharger (urban up to 72 KW vs. extra-urban up to 110 KW)

Charge curve of the battery itself.

Edit: Former poster explained it perfectly.

 

[TexasEV]

@a.void are you trying to be obtuse or do you really not understand that kW and kWh measure two different things? How you are charged for supercharging has nothing to do with the size of your battery. Perhaps it would help if you understood why some states have Tier 1 and Tier 2 rates. Tesla is selling energy so it would prefer to charge by units of energy which are kWh. This is how your battery capacity is measured, 60 kWh or 85 kWh or whatever. For example, in California it’s 26 cents per kWh. However some states don’t allow Tesla to charge for units of energy because it’s not an electric utility. It has to charge by the minute of use rather than how much energy is delivered. With one per minute rate would mean that people would be paying much more for a unit of energy delivered at 20kW power when the battery is almost full, for example, compared to 110 kW power when the battery is almost empty— because they’re getting much less energy per minute at 20kW power then at 110 kW power. So Tesla made two tiers. It charges less per minute when energy is being delivered at lower power (<60kW) than when it’s being delivered at higher power (>60 kW) in order to very roughly approximate charging by the kWh in states where it’s not allowed to do so. This is not a scam— actually it’s to your advantage that Tesla does this rather than simply charging 20 cents/ min regardless of how how much energy you get in that minute, it only charges 10 cents/ min when you’re getting less energy in that minute.

 

[JasJ]

Unless you need a full battery for whatever reason, Tier 1 is a waste of your time and a waste of supercharger stall time as the car is adding 'power' at a slow rate. Best bang for the buck is Tier 2 when the battery is pulling in 'power' at the maximum from the supercharger. Typically this is when the battery is between 15-55% state of charge.

My conclusion is Tier 2 is better as when I'm at a supercharger, I'm travelling and arrive with a low state of charge and charge just enough to get to the next supercharger with the battery at 10-15%. This minimizes time at a Supercharger when travelling while maximizing 'power' to the car on a per minute basis.

If you are just out shopping and want to use(waste) a lot of time at an urban supercharger, then sure go for Tier 1 when the battery is more than half full.

 

[a.void]

Thanks all for helping to provide some clarity. Obviously, I had some gaps understanding.

I guess everything i was charged with Tier 1 vs Tier 2 appeared opposite what was explained with lower battery= Tier 2.
From explanations above, it appears I should have been tier 2 for much longer. With only 2 other cars at the station, what would have kept me at Tier 1?

 

[brkaus]

The issue is the battery can only take high rate of charge (tier 2) when it is at a low state of charge and optimal temperature. Had you plugged in at a much lower charge level it would have been at tier 2 for a longer term.

 

[ewoodrick]

Thanks all for helping to provide some clarity. Obviously, I had some gaps understanding.

I guess everything i was charged with Tier 1 vs Tier 2 appeared opposite what was explained with lower battery= Tier 2.
From explanations above, it appears I should have been tier 2 for much longer. With only 2 other cars at the station, what would have kept me at Tier 1?

Let's put it other words. Charging is most expensive when the Supercharger is delivering the most power. The highest power is at the beginning of a charge and rolls off from there and eventually gets cheaper. It may be, for a full charge, that you spend about the same amount of money on each, only because it takes twice as long to charge the last 1/3 of the batter as it did the first.

 

[tecis]

Let's put it other words. Charging is most expensive when the Supercharger is delivering the most power.

No. Charging ist most expensive in Tier 2 when it's really close to 60 Kw, yet still slightly above that and cheapest if it's slightly below 60 Kwh to be in Tier 1.


If you're charging with let's say 100 KW, yet only get billed for Tier 2 which is 60 KW and up, you pay relatively less than if you only charge with 72 KW (max at urban chargers).

Tier 2:


In TX, 1 minute supercharging over 60 KW costs you 0.20 USD currently, under 60 Kw it's 0.10 USD.

If it's done at 100 KW, you get 100/60 = 1.67 KWh for 0.20 USD. // 0.12 USD/KWh

If done at 72 KW, you get 72/60 = 1.20 Kwh for 0.20 USD. // 0.167 USD/Kwh

that's 32 % more.


Tier 1:

58 KW (it does usually not stay there for very long according to the charging curve)

58/60 = 0.97 for 0.10 USD // 0.103 USD/Kwh

40 KW (usual charging speed once above 70-75 % SOC)

40/60 = 0.66 for 0.10 USD / 0.15 USD/Kwh


Therefore the best charging method would be:

a) Tier 1 slightly below 60 Kw

b) Tier 2 as high as possible

 

[NOLA_Mike]

Thanks all for helping to provide some clarity. Obviously, I had some gaps understanding.

I guess everything i was charged with Tier 1 vs Tier 2 appeared opposite what was explained with lower battery= Tier 2.
From explanations above, it appears I should have been tier 2 for much longer. With only 2 other cars at the station, what would have kept me at Tier 1?

In addition to what everyone else has already pointed out WRT explanations as to why the charging session remained below 60 kW I would add:

Most folks (but not all) know that you if you plug into a "shared stall" (i.e., if you plug into stall 2A and someone else is charging on 2B) you will get reduced power since the two cars are sharing the same charger.

Lastly, sometimes the superchargers at a particular location are just not operating up to full capacity. This could be a problem that needs to be addressed and fixed in the charger by Tesla or it could be a problem with the supplied power from the utility, etc.

I've learned from experience that if all else looks like it should be charging faster (battery current state of charge, ambient temperature, etc.) then sometimes just changing stalls (if you're on 2A/B move to 1A/B or 3 A/B) and that will often result in faster charging speeds closer to what you were expecting.

Mike

 

[a.void]

Thanks again for everyone's detailed info.

I needed real newbie clarification

 

[vickh]

If you are just out shopping and want to use(waste) a lot of time at an urban supercharger, then sure go for Tier 1 when the battery is more than half full.

In addition to what everyone else has already pointed out WRT explanations as to why the charging session remained below 60 kW I would add:

Most folks (but not all) know that you if you plug into a "shared stall" (i.e., if you plug into stall 2A and someone else is charging on 2B) you will get reduced power since the two cars are sharing the same charger.

Mike

so if not in hurry, better to share stall? (as long as other guy is still there)

 

[timk225]

Tesla could change the point at which it switches from Tier 1 to Tier 2 rates. Instead of when it is charging at 60, it could be at 55 or 70 or whatever, but I guess they have figured out that switching it at 60 is the most fair, based on the amount of time over and under 60 for the average charging session.

 

[vickh]

Tesla could change the point at which it switches from Tier 1 to Tier 2 rates. Instead of when it is charging at 60, it could be at 55 or 70 or whatever, but I guess they have figured out that switching it at 60 is the most fair, based on the amount of time over and under 60 for the average charging session.

thx.. How does 60 Kwh translate to miles for a SR?

 

[Rocky_H]

thx.. How does 60 Kwh translate to miles for a SR?

Here is where understanding the difference between kilowatts and kilowatt hours really matters, and you are mixing them up.

This is not talking about kWh. Notice that the comments before you don't say kWh? They say kW. Kilowatts is the charging power. It is the speed at which energy is going into the car. So no, it can't translate to miles at all, because it's not an amount of energy.

This tier 1 and tier 2 thing is saying that when the charging speed is really fast, like 100+ kilowatts, then they will charge a higher rate per minute, because you are getting more energy per minute. And then when the power (charging speed) drops below 60 kilowatts, then they charge less per minute, because you are getting less energy per minute.

 

[justsomeguy]

Tesla could change the point at which it switches from Tier 1 to Tier 2 rates. Instead of when it is charging at 60, it could be at 55 or 70 or whatever, but I guess they have figured out that switching it at 60 is the most fair, based on the amount of time over and under 60 for the average charging session.

I kind of agree, or at least they should make an exception for Urban superchargers which cap out at 72kW and is absolutely ridiculous to double the price for minimal gain.

Then again, these regulators should just let them sell based on actual consumption so we don't have to deal with this *sugar*.