In face of White House threats, Postal Service doubles down on gas trucks Environmentalists call this a 'once-in-a-generation opportunity'

dailycallernewsfoundation.org/ ^ | 2/7/2022 | THOMAS CATENACCI

[JD_UTDallas]

Here is commercial service with mutiple times per day supercharging 400,000+ miles on a model S. Tesla says their new packs will be a better chemistry nolonger using cobalt at all and capable of daily supercharging with a 3000 to 5000 full DOD cycle life.

https://electrek.co/2018/07/17/tesla-model-s-holds-up-400000-miles-3-years/

[TexasGator]

“Well that’s obviously not right. An average route going an average of 13.6mph for an average of 6 hours gives an average distance of 82 miles, not 21.”

In my neighborhood, they stop to open the mailbox!

[TexasGator]

Not all motors are created equal:

[TexasGator]

“So constant slow movement, top-and-go, will deflate your battery much faster (just like a regular gas/diesel!) “

Actually not. EV motors draw no current when stopped. Also, EV’s have regenerative braking.

Perhaps you ignore the fact that EV’s get better ‘mileage’ in the city versus highway.

[TexasGator]

“and the mean?”

The design spec for range is 70 miles which is more than 95% of the routes.

[TexasGator]

“and the mean?”

The design spec for range is 70 miles which is more than 95% of the routes.

[JD_UTDallas]

Average USPS ROUTE:

Distance: 20.8 miles
Speed: 13.6 mph
Route time: 6 hrs

That average speed is average moving speed the time is total time. Think about how many times the postman gets out of the truck to walk packages up to the door. Only to creep up to the next address drop mail in the box then creep to the next door drop get out, walk get back in. The ratio of stopped to moving time is nearly four to one.

20.8 miles with an average moving speed of 13.6 is 1.5.. Hours of actual movement and 3.49 hours of hoofing it or idling sorting packages something I see my postman do at the end of the street for half an hour in the back of the truck getting things ready for his next blocks of drop offs moving things to be in arms reach for the next few streets drops.

I do a lot of city driving my S60 has multiple trip ODO and also has a current trip summary for every time you turn on the key and move it.

The metrics are total run time, total distance,total moving time,total stopped/idle time,total avg speed, avg moving speed,avg fuel econ, avg moving fuel econ.

That said in prime time snarled city traffic my avg total speed is frequently less than 15 mph with avg moving speeds in the mid 20s to cover 10 to 15 miles in the core of DFW. it is little surprise that a vehicle that literally goes door to door for an 8 hour shift would avg less than 20 mph. This type of drive cycle is ideal for a series hybrid drive train why because with a small battery pack to take up braking energy as regenerative 80% can ne returned to accelerate the vehicle to next stop dozens of feet away and then regen again. This is why Prius get 55+ mpg in the city they do better in stop n go due to regen. The other thing is since you can use a tiny 500cc or 800cc motor to run a generator of 25kw or so you then run it at peak efficiency only to.charge the pack when it gets low then shut it down again you never have the low BMEP operating points in a properly designed series hybrid. While a modern diesel might be 43% net eff. At a BMEP of 20 bar its much less than 12% at 2 bar which is low speed cruising off the motorway even at motorway speeds a 2L diesel is only pulling 5 bar BMEP or less and less than 25% eff. A small otto cycle petrol engine running at 15 bar is 40% eff. This is the operating point a series hybrid is designed for. Petrol motors are 1/3 the cost of diesels especially the small ones under a liter of displacement. You can get 75kw per liter at 3600 rpm and 15 bar with 40% net eff. Ideal for a stop go.duty cycle. A vehicle of mail truck size would be in the 50 plus mpg with a 500cc generator driving a 5kwh pack and a 100kw main motor LiFePO4 cells will easily take a 20C discharge rate which is pedal to the floor, how many times do you see a mail truck burn out? Most of the time its idling and burrrr twenty feet next mail box and screech to a halt only to burrrr at 1200 rpm to the mext mail box. Absolutely ideal for a series hybrid. For those routes that you know for sure are under 40 miles a 10kwh pack could cover the distance with out even needing a generator go full EV for those routes. The small 500cc genny removes the range anxiety set it up to be flexfuel easy to do with modern ECU and fuel injectors so you can run it on ethanol,methanol,butanol or any combo of those are biofuels makes the greens happy and much lower emissions than petrol. Better yet put a small CNG tank and run the 500cc off landfill or sewage treatment plant methane again the greens are happy. CNG is a hundred times cleaner than liquid petrol in particulates, twice as clean vs NOx, and has zero sulfur dioxide. Clean air friendly and oil lasts twice as long due to no fuel dilution or particulates on the rings or cylinder walls with gas based fuel. You could also use propane or butane to get the same effects.

[TexasGator]

" they run best (load vs rpm(power draw)) at around 75-80% of max rpm."

This chart shows efficiency band larger at lower rpms.

EV HVH410 electric motor efficiency Credit: BorgWarner

[Svartalfiar]

In my neighborhood, they stop to open the mailbox!

So? We're talking averages - stopping means they're adding to total time, while adding datapoints of 0 velocity. That's included in the average data. That's why their average speed is so low - they aren't driving 13mph on every road in between their stops!

[Svartalfiar]

That average speed is average moving speed the time is total time.

Is that only moving speed? Sure, that would make a difference in the math but that's not how the number was described - average velocity and average time are usually given as concurrent data, not one of them being partial data and the other being full time.

[TexasGator]

“they aren’t driving 13mph on every road in between their stops!”

Not on every road. The data says ‘average’. Some are faster, some are slower. In every neighborhood I have lived, I would say the number is close.

[Svartalfiar]

Actually not. EV motors draw no current when stopped. Also, EV’s have regenerative braking.

It's not any current draw when they're stopped, it's the simple fact that more energy is required to overcome inertial forces and friction, than to maintain a velocity. Every time you completely stop and have to restart, that's extra energy required that a constant velocity does not have to expend.

And yes, regenerative braking recovers some power spent, but that's only when actively braking, and only a fractional amount of the power spent to accelerate the vehicle to that speed. Engine braking, which many EVs utilize instead of active braking, does NOT recover anything. I will say though, USPS drivers likely actively brake much much more than the regular Tesla driver.

[TexasGator]

“Engine braking, which many EVs utilize instead of active braking, does NOT recover anything.”

Help me out? Since EV’s have no engine, how do they accomplish this?

[JD_UTDallas]

The last gen Tesla packs go 300,000 plus in heavy duty commercial services with 10% pack degradation. 20% is the replacement point. Look at these commercial services vehicles the model S is.Absolutely abused in a way no normal driver would multiple super charges per day and constant discharge. The first pack made it top 196,000 with 6% loss after that kind of abuse. It was warranted out.

https://electrek.co/2018/07/17/tesla-model-s-holds-up-400000-miles-3-years/

Currently Tesla packs are being switched to Modular so individual cell modules can be replaced not the whole pack. Tesla is designing the model 3 for taxi use with a million mile pack and if any individual module goes under 20%. Tesla is already the world leader in the $/kwh metric and they are dropping fast they plan to use GigaAustin to break the $65 barrier before 2025.
This is the tech tesla is moving too. 20000 cycle life or more.

“Back in October, the head of Tesla’s battery research team, Jeff Dahn, shared some details of his research during an Energy Storage & Sustainable Engineering videoconference. Dahn revealed that, after three years of testing, he found that his cells had a lifespan of over two million miles. He has tested his battery over 20,000 cycles at a depth of charge-discharge of 100%, and found that his battery can last 15,000 cycles and still have 90% of its capacity. If we multiply 15,000 by his estimated driving range of 217 miles, we get 3.25 million miles in the worst-case scenario, which is when the battery fully discharged and charged every cycle. Therefore, Tesla’s progress in obtaining a battery that lasts a million miles is obvious.”

China is not far behind they have production ready 16 year calender life cells.

https://www.greencarreports.com/news/1128429_battery-giant-catl-million-mile-batteries-tesla

Its not if but when EVs dominate the market. There is a transition happening as sure and as fast as the first industrial revolution. Buggy whip makers and stage coach salesmen were luddites don’t be those guys in 2022. Welcome to the 21st century it’s gonna be a exciting one.

[TexasGator]

“It’s not any current draw when they’re stopped, it’s the simple fact that more energy is required to overcome inertial forces and friction, than to maintain a velocity. Every time you completely stop and have to restart, that’s extra energy required that a constant velocity does not have to expend.”

Advantage EV.

[TexasGator]

“And yes, regenerative braking recovers some power spent, but that’s only when actively braking,”

Wrong again. Coming off the pedal can also result in regeneration.

[JD_UTDallas]

Modern EV with larger packs such as a tesla S or 3 can do 70% regen. Have you ever test drove a tesla the regen can be a hundred or more horsepower worth it will throw you forward into you seat belt like you slammed hardware breaks. The only limit is what state of charge you pack is as and the HP rating of your motors if you have the AWD tesla all.wheels can regen it will do more than a G of deceleration the friction breaks only kick in under 10 mph or so you hardly feel the transition since all tesla are break by wire you just push the peddle the ECU does the magic.

https://electrek.co/2018/04/24/regenerative-braking-how-it-works/

[TexasGator]

“And yes, regenerative braking recovers some power spent, but that’s only when actively braking,”

2020-04-14

Characterizing Regenerative Coast-Down Deceleration in Tesla Model 3, S, and X 2020-01-0883

Tesla Motors vehicles utilize a regenerative braking system to increase mileage per charge. The system is designed to convert the vehicles’ kinetic energy during coast-down into electrical potential energy by using rotational wheel motion to charge the batteries, resulting in moderate deceleration. During this coast-down, the system will activate the brake lights to notify following vehicles of deceleration. The goals of this study were to analyze and quantify the regenerative braking behavior of the Tesla Model 3, S, and X, as well as the timing and activation criteria for the brake lights during the coast-down state. A total of seven Tesla vehicles (two Model 3, three Model S and two Model X) were tested in both Standard and Low regenerative braking modes. All three Tesla models exhibited similar three-phase behavior: an initial ramp-up phase, a steady-state phase, and a non-linear ramp-down phase at low road speeds. Phase 1 was less than one second in length. Phase 2 average steady-state decelerations observed were -0.19 g in Standard mode and -0.10 g in Low mode. At high speeds, test vehicles usually exhibited a low-jerk gradual ramp-up phase between the initial ramp-up and steady-state. The end of Phase 2 occurred when the speed of the vehicle dropped to 10-14 mph. All vehicles tested exhibited a delay in brake light activation relative to accelerator pedal lift-off and the resultant onset of longitudinal deceleration in Standard mode; this delay averaged 0.55 seconds for the Model S, 0.59 seconds for the Model X, and 0.35 seconds for the Model 3. The results of this study will provide insight for accident reconstructionists investigating crashes involving Tesla vehicles engaged in regenerative coast-down braking.

[Svartalfiar]

Not on every road. The data says ‘average’. Some are faster, some are slower. In every neighborhood I have lived, I would say the number is close.

And that average data usually includes time spent when velocity is zero. Take a regular car, reset your mileage estimator while driving on the road. it'll be really good - you might get 40, 50, 80+ mpg. Then stop at a red light (or just on the side of the road). Watch your mileage - it's gonna drop constantly as you add time but not position - your average becomes much lower, even though you aren't currently going anywhere.

13mph sounds close to me, if you include the zero-velocity time. Most drivers I've seen probably hit around 15-20mph in between mailboxen, and they don't stay at each very long. Then they're obviously going much faster when looping around streets or driving on the main streets.

[Svartalfiar]

Help me out? Since EV’s have no engine, how do they accomplish this?

My bad, "motor braking". An EV requires constant input on the 'gas' pedal, or the vehicle slows pretty quickly because without input power, the motors want to stop - and the stronger they are, they faster they'll stop your vehicle. Once you're used to it, you can stop and go through the city lights without ever actively braking - meaning no regenerative braking.