Thinking about a Tesla truck

[dirtbiker]

I never brought up anything about downshifting. You stated "going down a long grade with a near full battery could be problematic" and "I don't have any brakes".

And that is completely false, which is the second time for you in this thread. You just can't admit it. Both ICE and EV's would simply use the brakes. The only difference is the regenerative braking would be limited if the battery was near full.

I own 2 Tesla's and live on a steep hill. It is never an issue.

But do you do heavy towing with either of your two Teslas which would require regenerative engine braking to save your traditional brakes from overheating?

I think the point that ERD50 is making is that with a traditional ICE vehicle that is towing a significant load, you can (and should) use engine braking to slow down a vehicle on a long and/or steep downhill, as they can overheat brakes to the point of failure (which is why they have runaway truck ramps on steep downhills on many roads). This is done by downshifting. In an electric vehicle, the 'engine braking' is done through regenerative braking, which would be unavailable if the batteries were full. In this case, one would only have traditional brakes to slow down with, not any form of engine braking. If driving just a car that is not towing a heavy load, this would not be a problem. A heavily loaded trailer is a whole different story.

 

[Mr. Tightwad]

But do you do heavy towing with either of your two Teslas which would require regenerative engine braking to save your traditional brakes from overheating?

I think the point that Mr. Tightwad is making is that with a traditional ICE vehicle that is towing a significant load, you can (and should) use engine braking to slow down a vehicle on a long and/or steep downhill, as they can overheat brakes to the point of failure (which is why they have runaway truck ramps on steep downhills on many roads). This is done by downshifting. In an electric vehicle, the 'engine braking' is done through regenerative braking, which would be unavailable if the batteries were full. In this case, one would only have traditional brakes to slow down with, not any form of engine braking. If driving just a car that is not towing a heavy load, this would not be a problem. A heavily loaded trailer is a whole different story.

I don't do any heavy towing. But for anyone interested in the towing ability of a Tesla, google the "Model X tows a jetliner" video on YouTube.

Since you can slow down or stop in a Tesla/Bolt/Leaf with regenerative braking probably 95% of the time and only use the regular brakes rarely, I don't see how an EV owner would ever need new brakes. One more thing an EV owner wont need to repair.

 

[dirtbiker]

I don't do any heavy towing. But for anyone interested in the towing ability of a Tesla, google the "Model X tows a jetliner" video on YouTube.

Since you can slow down or stop in a Tesla/Bolt/Leaf with regenerative braking probably 95% of the time and only use the regular brakes rarely, I don't see how an EV owner would ever need new brakes. One more thing an EV owner wont need to repair.

Sorry, when I said "I think the point that Mr. Tightwad is making," I meant to say the point that ERD50 is making. I have edited my post.

Towing trains and planes on a flat surface is a marketing gimmick.

https://www.wired.com/story/the-physics-of-a-tesla-model-x-pulling-a-boeing-787/

Actual real world towing involves going up and down hills. If you're doing heavy towing with your EV, braking on downhills is definitely a concern if your batteries are full. It's not a question of wearing down your brake pads over time. It's a question of rapidly wearing your brakes during a long and/or steep downhill towing a heavy load if unable to engine brake (or regenerative brake). If you have never done any heavy towing, this may be a foreign concept to you. I don't mean this as an insult either, but from reading your posts that dismiss this issue, I assume that maybe you don't understand the concept. Again, I don't mean this as an insult.

 

[Fermion]

It really isn't going to be an issue though because it is something like 90% of truck owners only tow once per year.

 

[Mr. Tightwad]

50% of Tesla's are sold in CA. I've seen one Tesla that was towing something since I've been an owner. Perhaps when the 140,000 Tesla truck owners on the waiting list get their vehicles, towing will take place. But as Fermion said, probably not for many.

I would have thought McNeil (sp?) would have appeared discussing his Tesla stock profits by now.

 

[dirtbiker]

It really isn't going to be an issue though because it is something like 90% of truck owners only tow once per year.

I agree that the vast majority of people most of the time won't have anything to worry about. But for those that do tow more frequently, this is a valid concern. BTW, I'm not part of the group that does heavy towing frequently. I tow frequently, but heavy towing very infrequently.

 

[dirtbiker]

50% of Tesla's are sold in CA. I've seen one Tesla that was towing something since I've been an owner. Perhaps when the 140,000 Tesla truck owners on the waiting list get their vehicles, towing will take place. But as Fermion said, probably not for many.

I would have thought McNeil (sp?) would have appeared discussing his Tesla stock profits by now.

This thread is specifically about the Tesla truck, not the 100% of the other Teslas on the road. Tesla very boldly advertised the towing capacity of this truck. To dismiss towing as an afterthought is a bit reckless IMO.

 

[Ronstar]

I don’t like the styling of the Tesla truck, so I won’t be getting one. I’ll stick with my F150 until I move to a place where it won’t fit in the garage.

 

[unclemick]

I'm really curious to see how well those things sell in Texas.

Or Missouri.

2013 long bed plain bench seat Silverado with 78k miles.

Round trip to the farm is 240 miles.

Sooo do I lust or wait. 2021 is a ways off yet.

heh heh heh - meanwhile I can putz with my solar powered Polaris EV Ranger.

 

[38Chevy454]

I
The gas engine does not provide that good a braking power, because it is throttled, and not allowed to fully aspirate the air to compress in the upstroke.

And then, that compressed air is pushing the pistons down in the downstroke. A jake brake in a diesel engine that releases the compressed air at the top of the stroke vents and "wastes" that compressed air, and works a lot better. Is there any diesel pickup with a jake brake? I believe there are diesel motorhomes with one.

A real compression brake, what you refer to as a Jake brake (short for the technical name Jacob), has to be built into the engine design. BTW, Jacob is a brand name, which also does make exhaust brake components. None of the pickup class smaller diesel engines have compression brakes. Some have a form of exhaust brake, either controlled with the turbocharger or by an actual valve in the exhaust. Essentially chokes the exhaust flow to provide the resistance.
A real compression brake is very effective and can provide substantial braking capacity. That's why bigger truck or RV diesel engines have them.

 

[Fermion]

Right, so my Ford F150 with its tiny 2.7L Ecoboost engine really isn't that much better than a fully charged Cybertruck at braking...both are going to need to use the friction disk brakes.

The Ford does have pretty big rotors.

I think the Ecoboost can tow something like 8000 pounds. When we pull our sailboat over the mountain pass I am pretty careful to not ride the brakes and one time I was a little worried and pulled over to let some people pass and the brakes cool off. This is a ICE truck.

 

[Mr. Tightwad]

This thread is specifically about the Tesla truck, not the 100% of the other Teslas on the road. Tesla very boldly advertised the towing capacity of this truck. To dismiss towing as an afterthought is a bit reckless IMO.

1) If you don't want my opinions on Tesla (as an owner), consider the ignore button.

2) The towing capacity on the more expensive model of truck is 7 tons.

3) Consider me reckless. I won't be towing anything. If I see a second Tesla owner ever towing anything I'll report back.

 

[ERD50]

I never brought up anything about downshifting. You stated "going down a long grade with a near full battery could be problematic" and "I don't have any brakes".

And that is completely false, which is the second time for you in this thread. You just can't admit it. Both ICE and EV's would simply use the brakes. The only difference is the regenerative braking would be limited if the battery was near full. ... .

It is not completely false, and the difference is significant (for the case we are talking about).

I bring up downshifting because it is significant. It isn't relevant that you didn't mention it. As I said (correctly), in an ICE car, you can downshift to provide braking, and therefore limit the use of the friction brakes, and avoid overheating your brakes. That overheating can render your friction brakes useless. You absolutely would not "simply use the brakes" in an ICE. In an ICE, you would use engine braking, and occasionally supplement with friction brakes if needed. You are wrong, plain and simple.

In an EV with a full battery, you no longer have regen braking available, so you are fully reliant on the friction brakes - with the problems I just mentioned.

And again, for perspective, I acknowledge this isn't a common problem at all, and certainly isn't a reason to not buy an EV for almost anyone. But what I said is 100% true, don't tell me I'm incorrect - not incorrect once, not incorrect twice.

... I own 2 Tesla's and live on a steep hill. It is never an issue.

As I said, not likely to be a problem for most people, but that doesn't mean the potential does not exist. What I said is 100% correct.

I recall riding along with someone up/down Pike's Peak. As you come down, there are stop points where they measure your brake temperature with an IR gun, and will force you to stop if too high. It's a thing. Of course it's unlikely an EV would leave the top of Pike's Peak on a full charge, but that does not negate what I described. It is a potential problem on a full charge.

But do you do heavy towing with either of your two Teslas which would require regenerative engine braking to save your traditional brakes from overheating?

I think the point that ERD50 is making is that with a traditional ICE vehicle that is towing a significant load, you can (and should) use engine braking to slow down a vehicle on a long and/or steep downhill, as they can overheat brakes to the point of failure (which is why they have runaway truck ramps on steep downhills on many roads). This is done by downshifting. In an electric vehicle, the 'engine braking' is done through regenerative braking, which would be unavailable if the batteries were full. In this case, one would only have traditional brakes to slow down with, not any form of engine braking. If driving just a car that is not towing a heavy load, this would not be a problem. A heavily loaded trailer is a whole different story.

Yes, except the towing aspect is superfluous. It can happen with a car on a long downhill grade even w/o towing . In either case, the ICE will rely on engine braking and downshifting if needed. But an EV on a full charge, cannot use regen braking, so is totally reliant on friction brakes. The ICE is not. It's pretty simple.

-ERD50

 

[ERD50]

Right, so my Ford F150 with its tiny 2.7L Ecoboost engine really isn't that much better than a fully charged Cybertruck at braking...both are going to need to use the friction disk brakes. ...

No, your engine will still provide considerable engine braking relative to a fully charged EV. That fully charged EV has no regen, so is fully dependent on friction brakes.

To verify this, try taking it out on a lonely road, run it up to the speed limit, and then put it in neutral and see how long it takes to get to say 10 mph (where you take over with friction brakes). [ NOTE - driving in neutral may be against the law in some localities, you have been warned].

Next, repeat that, but let up on the gas, and downshift as you can to keep from over-revving the engine.

I'm certain you will feel significant engine braking. An EV on full charge would be like coasting in neutral.

And before the EV fans feel I'm picking on them, here's a positive statement about regen braking:

I'm pretty sure that the regen of the Cybertruck (or any Tesla/EV) on a less than full charge battery is far better at braking than the engine braking of any ICE (possible exception of one with Jake Brakes).

Try the experiment if you can, and report back.

-ERD50

 

[Fermion]

While I have not done the test you describe (truck is in storage, we are in our Ford Transit van on road trip) I have messed around with various techniques going down a big hill near our mountain property many times. The Ford F-150 2.7L ecoboost in drive vs in 2nd or 3rd just does not make a big difference going down the steep grade, nothing like the normally aspirated Toyota Tundra we had before with its 5.7L V8. That engine would really slow the truck down when in 2nd or 3rd gear.

I still think this is not a big deal. If someone is such a poor planner that they happen to be at 100% battery at the start of a 10 mile 7% downgrade, then they should pull over and plug in a coffee maker and toaster to the built in inverter on the Cybertruck, make a latte and bagel, while running the air conditioner or heater (depending on time of year). Pretty soon the battery will be under 90% and you can continue on.

 

[ERD50]

While I have not done the test you describe (truck is in storage, we are in our Ford Transit van on road trip) I have messed around with various techniques going down a big hill near our mountain property many times. The Ford F-150 2.7L ecoboost in drive vs in 2nd or 3rd just does not make a big difference going down the steep grade, nothing like the normally aspirated Toyota Tundra we had before with its 5.7L V8. That engine would really slow the truck down when in 2nd or 3rd gear.
...

OK, thanks for the fuller explanation. Sure, a 2.7L will not provide as much engine braking as a 5.7L, that's to be expected. But can you imagine going down that grade in neutral (which is what a fully charged EV would be like)? I'm thinking that would be a big difference, even compared to the 2.7L.

...
I still think this is not a big deal. If someone is such a poor planner that they happen to be at 100% battery at the start of a 10 mile 7% downgrade, then they should pull over and plug in a coffee maker and toaster to the built in inverter on the Cybertruck, make a latte and bagel, while running the air conditioner or heater (depending on time of year). Pretty soon the battery will be under 90% and you can continue on.

Agreed, I've never said it was a big deal. But when some posters (not you) try to tell me something is not true when I know it to be true, I respond.

It's a little like telling me that because a solar eclipse is rare, and only last a short time, that they don't exist. They do exist, we know that for a fact.

-ERD50

 

[ls99]

To comment on regenerative braking. In eletric trains which I workend on for around 15 years, regenenerative braking is used in two forms:

1. If the power line is at full line voltage the generated power is dissipated in braking resistors. Under heavy braking typically down to about 5 MPH the resistors tend glow red hot. Are designed to handle full current output of the motors as configured for generating. Below 5 MPH friction brakes are applied.

2. If the power is at less then full voltage, it indicates that there are trains using power. In this case the regenerated pwer is used by the other trains for propulsion.

In case of emergency braking only friciton brakes are applied along with what is known as Track brakes, which are electromagnets pulled to the rails and provide huge amount of friction.

AFIK electric cars do not have braking resistors to dissipate power when batteries are ful.

 

[Fermion]

I wonder if on the dual motor AWD version it would be possible to drive the rear wheels backward and the front wheels forward when going down a steep grade?

edit: It is too late at night...that didn't make any sense. But I mean if there would be some way of making the motors fight each other without messing up the control of the car.

Because the motors are water cooled, so you could treat them as big water cooled resistors if they could be shunted

 

[btdt22]

Does anybody keep with the original 'thread' anymore? If you want to change the subject why not start your own thread

 

[NW-Bound]

And before the EV fans feel I'm picking on them, here's a positive statement about regen braking:

I'm pretty sure that the regen of the Cybertruck (or any Tesla/EV) on a less than full charge battery is far better at braking than the engine braking of any ICE (possible exception of one with Jake Brakes)...

Totally agree on the regen braking of an EV being far better than engine braking on an ICE, in terms of applying a large braking force.

However, in the rare case where you already have a fully charged battery and you do not want the battery to blow up, what do you do?

I suspect that Tesla motor control software is smart enough in that case to slow down the car to a crawl down the descent, so that the friction brake has the chance to dissipate the heat.

This problem would be more acute and serious in an electric semi-trailer engine, which not just Tesla is building but other makers such as Nikola, Cummins, Volvo, Freightliner are also doing. Perhaps they all carry large resistive loads to dump that regenerative energy as needed.

 

[brewer12345]

1) If you don't want my opinions on Tesla (as an owner), consider the ignore button.

2) The towing capacity on the more expensive model of truck is 7 tons.

3) Consider me reckless. I won't be towing anything. If I see a second Tesla owner ever towing anything I'll report back.

So is a Tesla truck aimed at truck owners or existing Tesla owners (or Martians)? Because if Tesla owners are the target, everything you say is the last word. If this abomination is aimed at truck owners, I would suggest that your lack of experience with towing and other typical truck uses is making it hard for you to understand the problems with the design. Stated towing capacity is essentially meaningless. Towing burns a lot of energy and puts demands on the tow vehicle that have to be specifically considered in its design. I have towed the same trailer with a minivan that had a 3500 pound towing capacity and a truck with a 5000 capacity. Small difference, right? Completely different experience on the road. The minivan was scary to the point of not wanting to tow at all. The truck you hardly notice it behind you. Minivans are designed to carry lots of people, trucks are designed (in part) for towing. There are a bunch of other considerations, but I will spare you because I think some of them would be hard to explain if you haven't done a fair amount of towing.

I know a modest percentage of truck owners tow anything, take it off the pavement, haul anything more than some groceries, etc. That said, the marketing and image of these vehicles is all around such things. These images are important to the traditional truck buyer (of whom there are millions). For those of us who do use their trucks for these sorts of things, it isn't an image. The vehicle really does have to be able to do all of this stuff well and big 3 full sized pickups do so with gusto. If a would be competitor wants to run with the big dogs, it has to be able to convincingly do all of this stuff in any conceivable conditions.

 

[GrayHare]

After some smoothing of the edges the Cybertruck might more resemble the 1984 Honda HPX concept car. http://imcdb.org/vehicle_83647-Honda-HPX-1984.html

 

[NW-Bound]

Cybertruck will be heavy because of its battery. For that weight and also its power, I expect stability when towing a trailer will be quite decent. I wonder more about the reduced range when towing.

 

[brewer12345]

Cybertruck will be heavy because of its battery. For that weight and also its power, I expect stability when towing a trailer will be quite decent. I wonder more about the reduced range when towing.

Towing, when it is cold, when it is windy, when it...never mind.

 

[Mr. Tightwad]

So only 17% of the 146,000 reservations are for the cheapest model. The other 83% are split evenly among the other 2 models.