3 ms·

I actually think the math really works out well for semis given you can burn through your battery lifespan super quick. Let's say you take two 15 minute breaks

by nimos 9y ago

I actually think the math really works out well for semis given you can burn through your battery lifespan super quick. Let's say you take two 15 minute breaks + 30 minute lunch per day. That is 1 hour of charge time. Assuming you start from full battery and a 2% per minute supercharge rate (~what wikipedia has for the model s) that gives you an extra 120% battery. 1.9kwh per mile and driving 600 miles per day and you can get away with a 400kwh battery. Less actually but my understanding is you want to not charge to 100% for maximum lifespan. Not sure the optimal cost trade offs... 7 cents per kilowatt hour * 1.9 * 600 = ~$80 a day vs $2.7 a gallon * 600/6(mpg) = $270 a day $150/kwh for battery with 2000 full cycles is $85 dollars a day without interest(only ~2 year lifespan so w/e and presumably has some residual value also not taken into account) Seems to work out to about $100 a day in savings?? I feel like I must be off on numbers somewhere. Data on number of cycles doesn't seem to be particularly consistent.

struppi 9y ago
Magna has electric trucks as a short-range shuttle between factories. They charge during loading/unloading. So it certainly seems doable, at least for short-range transportation. https://investinaustria.at/en/news/2017/11/magna.php https://investinaustria.at/en/news/2017/11/magna.php I don't know about long-range. But I would be curious where you get the 1.9 kWh/mile and the 600 miles per day figure from?
- nimos 9y ago
  1.9 was sort of an average from googling. This seems like the most detailed source which has a slightly higher number. https://insideevs.com/tesla-semi-truck-battery-is-how-big/ https://insideevs.com/tesla-semi-truck-battery-is-how-big/ 600 is just random googling of what is a long but not super long day for most truck drivers.
donquichotte 9y ago
> $150/kw That's insanely cheap, if you can find a place where I can buy batteries for 150$/kWh, please let me know. The cheapest I found are still >300$/kWh. > 7cents/kWh In NY the price is ~0.2$/kWh [1] Also, a 400kWh battery weighs 2 tons. [2] [1] https://www.bls.gov/regions/new-york-new-jersey/news-release/averageenergyprices_newyorkarea.htm https://www.bls.gov/regions/new-york-new-jersey/news-release... [2] https://en.wikipedia.org/wiki/Energy_density https://en.wikipedia.org/wiki/Energy_density
- nimos 9y ago
  Tesla doesn't publish it's costs but based on what they've said it is a reasonable estimate[0] Cells in bulk are below 150[1] 7 cents per kwh is a very common industrial rate.[2] Maybe it is a bit low but it's a lot more reasonable than one of the highest residential rates in the country ($.2/kwh). Let's say 5000lb for batteries + cooling/wires. Semi's routinely have (200gallons *7) 1400lb in fuel or more and a ~500 hp ~3000lb diesel engine. I don't know what the electric equivalent would weigh exactly but Tesla's 362 hp motor is 70lb. Let's say a 500hp one weighs 500lb. 5000+500 - 1400 - 3000 = 1,100. Tractor weights are around 15-20k so ~5-7% weight increase with a pretty generous estimate for cooling/wires and engine weight assuming rest of the drive train is identical. [0] https://electrek.co/2017/02/18/tesla-battery-cost-gigafactory-model-3/ https://electrek.co/2017/02/18/tesla-battery-cost-gigafactor... [1]http://benchmarkminerals.com/lithium-ion-batteries-are-now-selling-for-under-140kwh-new-york-hears-on-benchmark-world-tour-2017/ http://benchmarkminerals.com/lithium-ion-batteries-are-now-s... [2]https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_a https://www.eia.gov/electricity/monthly/epm_table_grapher.ph...
  - SigmundA 9y ago
    I want electric vehicles to succeed more than anyone, but lets not delude ourselves: Tesla's batteries are not that energy dense, they are currently 140 Wh/kg[1]. A 400Kwh battery will weigh at least 6000 pounds. A 400Kwh will get you maybe 150 mile loaded range, 200 gallons of diesel in a semi is a 1300 mile range[2]. To compete with a 400Kwh battery pack you only need to carry 25 gallons of diesel. Charging a 400 kwh will take at least 3 hours on a supercharger, vs a few minutes for diesel. Its simply not practical for "long haul" as claimed. For it to be usable for long haul you need at least 500-600 miles for a days driving then charge overnight (even that is low for a truck driver). 600 miles is a 1200Kwh battery at 24,000 lbs costing more than the truck with some kind of faster charger so it can be ready in 8 hours. Bottom line diesel is 30x times as energy dense as current battery tech and that not even counting how much efficiency is left on the table for diesel, the various super trucks programs are showing real world 10+mpg on a semi vs the current 6.5mpg standard by doing secondary heat recovery like a power plant among other things. The Tesla semi might have some use for local urban delivery but I am highly skeptical of any "long haul" highway replacement claims, will be very interested in the real specifications come Thursday. [1] http://enipedia.tudelft.nl/wiki/Tesla_Model_S_Battery http://enipedia.tudelft.nl/wiki/Tesla_Model_S_Battery [2] https://insideevs.com/tesla-semi-truck-battery-is-how-big/ https://insideevs.com/tesla-semi-truck-battery-is-how-big/
djf1 9y ago
Aside from energy efficiency, the semi would be an attractive vector to introduce fully autonomous driving: 1. Feasibility: Many trucking routes avoid some of the most complex driving tasks (e.g. dealing with pedestrians, city traffic). 2. Labor Cost: In commuter travel, the driver _is_ the cargo, so the utility gain is offset: utility = cost(operation) - cost(occupancy) For shipping, in contrast, there is no occupancy requirement, so the gain is greater: utility = cost(operation)
- Fjolsvith 9y ago
  However, if the truck is autonomous, then DOT restrictions on hours of service for a driver no longer applies. So, the semi drives a longer day: requiring a bigger battery and longer charge times.

by nimos 9y ago

struppi 9y ago

Magna has electric trucks as a short-range shuttle between factories. They charge during loading/unloading. So it certainly seems doable, at least for short-range transportation. https://investinaustria.at/en/news/2017/11/magna.php https://investinaustria.at/en/news/2017/11/magna.php I don't know about long-range. But I would be curious where you get the 1.9 kWh/mile and the 600 miles per day figure from?

nimos 9y ago
1.9 was sort of an average from googling. This seems like the most detailed source which has a slightly higher number. https://insideevs.com/tesla-semi-truck-battery-is-how-big/ https://insideevs.com/tesla-semi-truck-battery-is-how-big/ 600 is just random googling of what is a long but not super long day for most truck drivers.

donquichotte 9y ago

> $150/kw That's insanely cheap, if you can find a place where I can buy batteries for 150$/kWh, please let me know. The cheapest I found are still >300$/kWh. > 7cents/kWh In NY the price is ~0.2$/kWh [1] Also, a 400kWh battery weighs 2 tons. [2] [1] https://www.bls.gov/regions/new-york-new-jersey/news-release/averageenergyprices_newyorkarea.htm https://www.bls.gov/regions/new-york-new-jersey/news-release... [2] https://en.wikipedia.org/wiki/Energy_density https://en.wikipedia.org/wiki/Energy_density

nimos 9y ago
Tesla doesn't publish it's costs but based on what they've said it is a reasonable estimate[0] Cells in bulk are below 150[1] 7 cents per kwh is a very common industrial rate.[2] Maybe it is a bit low but it's a lot more reasonable than one of the highest residential rates in the country ($.2/kwh). Let's say 5000lb for batteries + cooling/wires. Semi's routinely have (200gallons *7) 1400lb in fuel or more and a ~500 hp ~3000lb diesel engine. I don't know what the electric equivalent would weigh exactly but Tesla's 362 hp motor is 70lb. Let's say a 500hp one weighs 500lb. 5000+500 - 1400 - 3000 = 1,100. Tractor weights are around 15-20k so ~5-7% weight increase with a pretty generous estimate for cooling/wires and engine weight assuming rest of the drive train is identical. [0] https://electrek.co/2017/02/18/tesla-battery-cost-gigafactory-model-3/ https://electrek.co/2017/02/18/tesla-battery-cost-gigafactor... [1]http://benchmarkminerals.com/lithium-ion-batteries-are-now-selling-for-under-140kwh-new-york-hears-on-benchmark-world-tour-2017/ http://benchmarkminerals.com/lithium-ion-batteries-are-now-s... [2]https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_a https://www.eia.gov/electricity/monthly/epm_table_grapher.ph...
- SigmundA 9y ago
  I want electric vehicles to succeed more than anyone, but lets not delude ourselves: Tesla's batteries are not that energy dense, they are currently 140 Wh/kg[1]. A 400Kwh battery will weigh at least 6000 pounds. A 400Kwh will get you maybe 150 mile loaded range, 200 gallons of diesel in a semi is a 1300 mile range[2]. To compete with a 400Kwh battery pack you only need to carry 25 gallons of diesel. Charging a 400 kwh will take at least 3 hours on a supercharger, vs a few minutes for diesel. Its simply not practical for "long haul" as claimed. For it to be usable for long haul you need at least 500-600 miles for a days driving then charge overnight (even that is low for a truck driver). 600 miles is a 1200Kwh battery at 24,000 lbs costing more than the truck with some kind of faster charger so it can be ready in 8 hours. Bottom line diesel is 30x times as energy dense as current battery tech and that not even counting how much efficiency is left on the table for diesel, the various super trucks programs are showing real world 10+mpg on a semi vs the current 6.5mpg standard by doing secondary heat recovery like a power plant among other things. The Tesla semi might have some use for local urban delivery but I am highly skeptical of any "long haul" highway replacement claims, will be very interested in the real specifications come Thursday. [1] http://enipedia.tudelft.nl/wiki/Tesla_Model_S_Battery http://enipedia.tudelft.nl/wiki/Tesla_Model_S_Battery [2] https://insideevs.com/tesla-semi-truck-battery-is-how-big/ https://insideevs.com/tesla-semi-truck-battery-is-how-big/

djf1 9y ago

Aside from energy efficiency, the semi would be an attractive vector to introduce fully autonomous driving: 1. Feasibility: Many trucking routes avoid some of the most complex driving tasks (e.g. dealing with pedestrians, city traffic). 2. Labor Cost: In commuter travel, the driver _is_ the cargo, so the utility gain is offset: utility = cost(operation) - cost(occupancy) For shipping, in contrast, there is no occupancy requirement, so the gain is greater: utility = cost(operation)

Fjolsvith 9y ago
However, if the truck is autonomous, then DOT restrictions on hours of service for a driver no longer applies. So, the semi drives a longer day: requiring a bigger battery and longer charge times.