Understanding Destination Charger Speeds

[azred]

I realize this thread is about destination charging but seems to be addressing charging, in general, so here’s my situation: I have a late 2016 S and with my electrical setup can charge at 240/48, which the Tesla Support Page on Home Charging Installation says will produce 11.5kW and 34 mph. (My calculations suggest it is 34.8 mph — and I think I do get about 35 in reality — but perhaps the difference is rounding.)

I am also adding a Model 3 and that support page says I will get the same 240/48, but only if I get LR. Small battery is 2/3 of LR (32 vs 48 amps).

Now I (finally) get to my two questions. Why will I get 44mph on the LR 3 at 240/48 when I only get 34-35 mph on my S at 240/48? And what will I experience in terms of Supercharging the LR 3 (or short range 3) vs the S?

From what I have gathered, it looks like my LR 3 will charge faster than the S at home, but slower at Superchargers. Right?

 

[Rocky_H]

Now I (finally) get to my two questions. Why will I get 44mph on the LR 3 at 240/48 when I only get 34-35 mph on my S at 240/48? And what will I experience in terms of Supercharging the LR 3 (or short range 3) vs the S?

Ah, interesting question, but there is a sensible answer. Let's say you are filling a Ford F-150 pickup and a Ford Fiesta econobox. From the source, you can put in 1 gallon of gas per 10 seconds, let's say. The truck only got 15 miles in that 10 seconds, while the Fiesta got 35 miles in that 10 seconds. See? With the same amount of energy going into the vehicle, the one that is more efficient is getting more "miles" because it will be using that energy to go more distance.

 

[Rocky_H]

Suffice it to say, that a good rule of thumb, is that Amps * Volts * 3 = MPH -- and you can never 100% trust the data from Tesla (there are worse examples... don't get me started about the errors between the 'theoretical' Tesla DB and real life wall charger sites).

Yes, that is a good way to calculate it because it is more precise. Tesla can probably get an answer from the business owner of what amp of circuit level they were going to have it installed on. But voltage levels can be a little variable, and the people who work at the business might not even know if their building is on a 240 or 208V system. Tesla's default guess was that the vast majority of commercial properties will be 208V, so 8 and 16kW will usually be right for 50 and 100 amp breakers. But you found one of the rare exceptions, where it is a commercial property with 240V (and a little high, at that), so it's more like 9.5 and 19kW. Tesla had a lot of boilerplate descriptions they put in when they don't have specific information, such as "for patrons only" is always put on all of them by default unless they get specific information to change it to if they have a different policy.

 

[hmgolds]

I have a question regarding destination charging. Many will say something like "3 Tesla Connectors, up to 16kW". Does that mean the 16kw will be split among the cars concurrently charging? So 8kw if 2 cars are charging?

 

[eladts]

I have a question regarding destination charging. Many will say something like "3 Tesla Connectors, up to 16kW". Does that mean the 16kw will be split among the cars concurrently charging? So 8kw if 2 cars are charging?

It depends how the HPWCs were installed. They can each have dedicated breaker, but newer version can be set up so that up to four HPWCs share the same breaker and load-balance the power. The Tesla map has no indication for that.

 

[hmgolds]

Thanks. To be on the safe side, I'll assume shared if it says "up to".

 

[ucmndd]

The data on the destination charging page is entirely self reported by the property owners and quite often straight up wrong.

The great majority of the “up to 16kw” chargers I’ve visited are nowhere near that. Most all of these things are installed on 208v/40A circuits. Sometimes you’ll get a slower one at 30A, but very rarely have I actually seen one configured to deliver >40A.

Assume a 6-8kw charger and you’ll rarely be disappointed.

 

[Rocky_H]

Thanks. To be on the safe side, I'll assume shared if it says "up to".

That's not a great assumption. The "up to" language is boilerplate and was on every destination charger installation for many years before the newer wall connectors even came out that had any sharing capability. Whenever they would add any of these, they would always by default list "up to 16kW" for all of them, unless they got some different specific information from the site that got it installed. Most of the time, they wouldn't get any information back from the site about how it was installed, so that default wording just stayed there.