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Deadheading[0] is probably easy on the battery. Yet even empty, the Supercharger network doesn't reach far enough yet, and apparently the truck had to take up s

Deadheading[0] is probably easy on the battery. Yet even empty, the Supercharger network doesn't reach far enough yet, and apparently the truck had to take up several charging stations at "non-Super" chargers. Do things that don't scale, indeed. > Musk jokingly added that they used a 1,000-mile long extension cord, but he is actually referring a system made of extension cords that they have used to charge Tesla Semi prototypes at Tesla’s regular charging stations. ... People who have witnessed Tesla Semi prototypes charging at Supercharger stations have told Electrek that the system made of extension cords plugs into several Supercharger stalls at the same time and into several charge ports on the truck. Gas semi trucks can take 30 minutes to fuel, and electrics usually take vastly longer than gas vehicles to recharge. Megachargers will be the key to making these trucks actually viable. If they could get recharge times below refuel times, it would be a great advantage. --- > I wonder if ultimately it does come down to economics, with the Tesla Truck having 'regen' as quite a trick to play. The 'regen' should make descending a lot safer and obviously a lot more 'green' than normal engine braking. I am intrigued as to how that will work out crossing The Rocky Mountains as per the customer visit going on here. Regenerative braking stops helping when the battery is full - on my Camry Hybrid, after going down about 600 feet of vertical drop, it actually starts the engine to engage engine braking. Also, there's a limit in the rate of how much velocity energy can be converted to electricity by regeneration, per second. For instance, slowing from 65 MPH to 64 can take over a second using only regenerative brakes. [0] https://en.wikipedia.org/wiki/Dead_mileage https://en.wikipedia.org/wiki/Dead_mileage

cptskippy 8y ago
> it actually starts the engine to engage engine braking. The engine isn't firing is it? Engine braking doesn't require the cylinders to fire.
djrogers 8y ago
> apparently the truck had to take up several charging stations at "non-Super" chargers. No, these were multiple connections to Tesla Superchargers - not ‘regular’ chargers. This is necessary because the Tesla Hyperchargers that are being developed to quickly charge the Semis are not deployed anywhere yet.
- stephengillie 8y ago
  How many "non-Super" chargers does a single truck take? Does it take up the entire station? How soon are the Megachargers planned?
  - Latteland 8y ago
    they have only announced them they will build them when the tracks are out. they have continually built their superchargers, keeping up with demand. this year with their incredible increase in vehicle production for the model 3 they have also increased their rate of new superchargers. See supercharge.info for some details. But it will still be hard for them to keep up with new vehicle production.
    - stephengillie 8y ago
      So how will they charge the numerous trucks they've sold before the full Megacharger network is available? Will a truck roll into a Supercharger and take up half the chargers?
      - jakobegger 8y ago
        Maybe early adopters will set up their own charging infrastructure? Seams feasible if you limit it to few routes.
        stephengillie 8y ago
        I'll bet Tesla's EULA forbids setting up your own Megacharger station.
        Latteland 8y ago
        It would be stupid for tesla to reduce charging opportunities which are a crucial need for a new truck. an example of how telsa deals with this is that tesla sells adapters so you can charge a tesla at a high speed chademo charger today, and also for j1772. tesla asked for a higher amperage j1772 standard that any car manuf. can support but only tesla really uses it (80 amp 220v).
Latteland 8y ago
A tesla can slow down much much faster than 1 mile an hour per second with regenerative brakes. As you said, if the battery is really full (like 99%, but not 80%) even on a tesla it uses regular braking when full, but once you drive a tesla 10 or 15 miles it has room to do regen braking. also you don't typically charge it to 100% every day, i only charge to the recommended ~90% - so i'm always ready for regen. You drive it in a certain mode where you don't need to use the brakes much, just take your foot off the gas pedal and it slows down rapidly. That's not good enough for say emergency stopping on the freeway but I don't need to emergency stop much. But on a tesla at least the regen braking takes speed off much faster. there are two things at play, just taking off the power will start to slow you down, but you can see the breaking impact when you car is using negative power.
- stephengillie 8y ago
  Kinetic energy increases at the square of velocity - so a 4400 lb car, accelerating from 64 MPH to 65 uses 7.25 KW, while going from stopped (0 MPH) to about 7 MPH uses slightly more, 7.75 KW. It takes additional energy to add energy to a system that already has some energy. For example, recharging a partially-full battery from 70% to 90% will take more energy (or time) than charging from 5% to 25%. At 65 MPH, it takes my Camry Hybrid over a second to absorb 1 MPH and reduce to 64 MPH, with only regenerative braking. At 35, it can absorb several MPH per second. Like a Tesla, the regenerative braking is always slowing the car down, but unlike a Tesla, it only regenerates at 5%-10% until the brake pedal is pressed, which is reflected by the "tachometer" dipping down into the blue CHG section.
  - davidgould 8y ago
    > a 4400 lb car, accelerating from 64 MPH to 65 uses 7.25 KW My Chevy Spark EV can regenerate at up to 60 KW. Forward drive tops at 100 KW. The regen limit is due to the battery charge rate, the bigger the battery, the more charge it can accept. > It takes additional energy to add energy to a system that already has some energy. For example, recharging a partially-full battery from 70% to 90% will take more energy (or time) than charging from 5% to 25% Why do you say "additional energy"? Do you mean "additional time", because that makes some sense as DC quick charging usually tapers off in rate as the battery becomes full. Please explain this if you actually mean additional energy as it is confusing.

cptskippy 8y ago

> it actually starts the engine to engage engine braking. The engine isn't firing is it? Engine braking doesn't require the cylinders to fire.

djrogers 8y ago

> apparently the truck had to take up several charging stations at "non-Super" chargers. No, these were multiple connections to Tesla Superchargers - not ‘regular’ chargers. This is necessary because the Tesla Hyperchargers that are being developed to quickly charge the Semis are not deployed anywhere yet.

stephengillie 8y ago
How many "non-Super" chargers does a single truck take? Does it take up the entire station? How soon are the Megachargers planned?
- Latteland 8y ago
  they have only announced them they will build them when the tracks are out. they have continually built their superchargers, keeping up with demand. this year with their incredible increase in vehicle production for the model 3 they have also increased their rate of new superchargers. See supercharge.info for some details. But it will still be hard for them to keep up with new vehicle production.
  - stephengillie 8y ago
    So how will they charge the numerous trucks they've sold before the full Megacharger network is available? Will a truck roll into a Supercharger and take up half the chargers?
    - jakobegger 8y ago
      Maybe early adopters will set up their own charging infrastructure? Seams feasible if you limit it to few routes.
      - stephengillie 8y ago
        I'll bet Tesla's EULA forbids setting up your own Megacharger station.
        Latteland 8y ago
        It would be stupid for tesla to reduce charging opportunities which are a crucial need for a new truck. an example of how telsa deals with this is that tesla sells adapters so you can charge a tesla at a high speed chademo charger today, and also for j1772. tesla asked for a higher amperage j1772 standard that any car manuf. can support but only tesla really uses it (80 amp 220v).

Latteland 8y ago

A tesla can slow down much much faster than 1 mile an hour per second with regenerative brakes. As you said, if the battery is really full (like 99%, but not 80%) even on a tesla it uses regular braking when full, but once you drive a tesla 10 or 15 miles it has room to do regen braking. also you don't typically charge it to 100% every day, i only charge to the recommended ~90% - so i'm always ready for regen. You drive it in a certain mode where you don't need to use the brakes much, just take your foot off the gas pedal and it slows down rapidly. That's not good enough for say emergency stopping on the freeway but I don't need to emergency stop much. But on a tesla at least the regen braking takes speed off much faster. there are two things at play, just taking off the power will start to slow you down, but you can see the breaking impact when you car is using negative power.

stephengillie 8y ago
Kinetic energy increases at the square of velocity - so a 4400 lb car, accelerating from 64 MPH to 65 uses 7.25 KW, while going from stopped (0 MPH) to about 7 MPH uses slightly more, 7.75 KW. It takes additional energy to add energy to a system that already has some energy. For example, recharging a partially-full battery from 70% to 90% will take more energy (or time) than charging from 5% to 25%. At 65 MPH, it takes my Camry Hybrid over a second to absorb 1 MPH and reduce to 64 MPH, with only regenerative braking. At 35, it can absorb several MPH per second. Like a Tesla, the regenerative braking is always slowing the car down, but unlike a Tesla, it only regenerates at 5%-10% until the brake pedal is pressed, which is reflected by the "tachometer" dipping down into the blue CHG section.
- davidgould 8y ago
  > a 4400 lb car, accelerating from 64 MPH to 65 uses 7.25 KW My Chevy Spark EV can regenerate at up to 60 KW. Forward drive tops at 100 KW. The regen limit is due to the battery charge rate, the bigger the battery, the more charge it can accept. > It takes additional energy to add energy to a system that already has some energy. For example, recharging a partially-full battery from 70% to 90% will take more energy (or time) than charging from 5% to 25% Why do you say "additional energy"? Do you mean "additional time", because that makes some sense as DC quick charging usually tapers off in rate as the battery becomes full. Please explain this if you actually mean additional energy as it is confusing.