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According to Jennifer Homendy, Chair of the National Transportation Safety Board, modern electric vehicles are getting too heavy and too powerful. Homendy stated that she was concerned that the increasing size, power and performance of electric vehicles could result in a rise in the risk of severe injuries and death for all road users.
The NTSB Chair, in her speech, drew attention to the GMC Hummer EV, mentioning its massive kerb weight of 4,110 kg, while still being able to accelerate from 0 - 60 mph in 3 seconds. She further added that the Hummer EV's gross weight is 4,785 kg, of which the battery alone weighs around 1,315 kg - almost the same weight that of a Honda Civic. She also mentioned how the electric version of the Ford F-150 is 900 - 1400 kg heavier than its non-electric counterparts & how this could have a significant impact on the safety of road users.
Reports mentioned how heavier vehicles impart more energy during a crash, compared to lighter ones. Also, how small increases in speed become big increases in kinetic energy during a crash; and while there are set speed limits, there isn't a similar restriction on the kerb weights of passenger vehicles.
Other examples include a graph showing the increase in vehicle mass between 1993 and 2023. Reports take examples of the Ford F-150, BMW 3 Series and even the MINI to showcase the increasing weight of vehicles, while also comparing them to the newest EV in the brand's lineup.
Reports also state that crash tests conducted by the National Highway Safety Administration have changed over time. The tests are now conducted at higher speeds and at different angles. While this has improved passenger safety, pedestrians and other road users are still at high risk, especially with customers buying larger SUVs compared to smaller sedans in the past. This is further combined with EVs having to cram larger batteries in their vehicles to offset long charging times.
Source:
ARSTechnica Link to Team-BHP news
This is a very valid point.
Regarding weight, I don't think there is an immediate solution till battery technology advances and light weight batteries are made possible. It is also a waste of energy lugging around all that weight all the time. This is also a point that can be used in favour of other green energy technologies like hydrogen.
Regarding the acceleration, I do believe there should be a regulatory restriction on the amount of acceleration possible on public roads. Not everybody is capable of handling sub 5 sec 0-100 KMPH acceleration safely.
Well, if she is really that concerned, as anyone rightly should be, then she should implement more stringent safety standards for VRUs (Vulnerable Road Users), along the lines similar to EU.
Tata Tiago Electric took a safe approach to how much they want their car to accelerate vs weight gain. For a little searching, I could see that the Electric version is about 300Kgs heavier than their Petrol Counterpart. However, if we fill it to capacity, the difference can be as low as 250 Kgs.
In retrospect, we still have a similary accelerating car, with almost similar driving dynamics, at about 30% extra weight. And if it was built with an all EV platform, I am guessing, the weight can be optimised even further, avoiding the Tunnel, a few engine mounts etc.
It was Tesla's story, that they wanted to build a fast accelerating car. They put a lot of engineering into it.
But, slowly, EV manufacturers are turning away from fast acceleration to eeking out range.
For that, the first pre requisite is to make cars lighter.
https://www.youtube.com/watch?v=0G7Egi36C4M
The EQxx does exaclty the same. And much more
A CD of 0.16, makes it accelerate if you take your foot off the pedal. All carbon fiber body makes it weigh less than 2 tonnes. It still has a lot of performance, but if people decide Sub 10 second 100 is no-body's requirement, and range is a primary concern, packing l smaller capacity batteries should be an easy answer.
Who on earth would want their pickup truck to accelerate to 100 in less than 3 seconds? Cargo would simply roll off from its back :D
I would be more worried about the brakes than the acceleration.
This seriously is concerning. There needs to be weight restrictions on batteries. Only then manufacturers will look to improve the weight. Else, they will simply increase the power and go ahead. Seriously, what would happen if a 4.1 ton EV crashed on a 1.3 ton civic. Even if civic has more structural strength, a monster car that crashes on you at higher speeds, weighing more than 3 times, it's unlikely the civic passengers survive.
This is just the start.
Tesla has earlier said once that, they would be moving away from LiIon, (which are the lightest batteries) to NiMh or other chemistries. They again invested in recycling li plants though at a later point, but considering how expensive to recycle/extract Li when compared to other widely used chemistries, we might have to use other combinations too.
Till date, no company has officially launched a mass produced Non Lithium battery cars. That would have given us a better picture. On a lighter note, :uncontrol My <2KVA Inverter battery weighs ~50Kgs. with this as a base line, a 60 KV EV car would need 30 batteries and would end up weighing 1500 Kgs. To hold such heavy battery, the shell must go up in weight and would push the car into 3000 odd kgs territory.
On the contrary, major EV manufacturers place the battery packs lower and a significant amount of metal is used in protecting the battery packs from external elements, which is the primary reason. Maybe if any company experiments with Carbon-Fibre as the packaging alloy would give us a better picture. But the frame weight should grow as we cannot weld carbon-fiber with chasis, which again complicates the situation further.
I feel we are just going through those crazy years phase with regards to BEVs. The race for the quickest acceleration numbers will cool down and so will the need for heavier BEVs. Manufacturers need some novelty stuff to get people to try BEVs and hence we will see all sorts of innovation and gizmos. Will die off pretty soon and I guess the focus would be more on practicality.
Another aspect is the load on infrastructure. Ofcourse, there are heavier ICE vehicles but people will be used to some size: weight ratio, which is not the case in BEVs. Already I believe many countries have upper kerb/gross weight limits for passenger vehicles, still if there isn't regulations things could go south.
Quote:
Originally Posted by Mustang_Boss
(Post 5478740)
Tesla has earlier said once that, they would be moving away from LiIon, (which are the lightest batteries) to NiMh or other chemistries.
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This is so incredibly incorrect that I request mods to delete or edit the post given the quality of our forum. Tesla never even considered NiMH batteries for their EV's. All of their batteries are Lithium Ion batteries of differing cathode chemistries - LFP, NCM, NCA etc
Quote:
Originally Posted by Mustang_Boss
(Post 5478740)
They again invested in recycling li plants though at a later point, but considering how expensive to recycle/extract Li when compared to other widely used chemistries, we might have to use other combinations too.
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Tesla's former engineer has a start up which is tackling exactly this and quite successfully I may add.
https://www.entrepreneur.com/green-e...%20Thinks%20He,'
Given batteries are more than 90% recycleable, once there are enough electric cars on the road, we wont require as much extraction of rare earth metals as we do now. A platonic ideal would be enough recycling to cover the ongoing battery production.
Quote:
Originally Posted by Mustang_Boss
(Post 5478740)
Till date, no company has officially launched a mass produced Non Lithium battery cars. That would have given us a better picture. On a lighter note, :uncontrol My <2KVA Inverter battery weighs ~50Kgs. with this as a base line, a 60 KV EV car would need 30 batteries and would end up weighing 1500 Kgs. To hold such heavy battery, the shell must go up in weight and would push the car into 3000 odd kgs territory.
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Reva was one which is why it was slow, had poor range, degradation and weighed a lot.
Quote:
Originally Posted by Mustang_Boss
(Post 5478740)
On the contrary, major EV manufacturers place the battery packs lower and a significant amount of metal is used in protecting the battery packs from external elements, which is the primary reason. Maybe if any company experiments with Carbon-Fibre as the packaging alloy would give us a better picture. But the frame weight should grow as we cannot weld carbon-fiber with chasis, which again complicates the situation further.
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Welding is not the only way to join metal with carbon fiber. BMW already does this one some of their ICE and EV cars. Speaking of Tesla, they have already started manufacturing structural battery packs with their 4680 batteries and casting for the whole front and the rear of the Model Y.
I cant speak for other car manufacturers but Tesla's are not much more heavier than a ICE car. As an example - a Model Y is around 19xx kgs and is 4750mm long, a BMW X3 is smaller and weighs anywhere from 1700 kgs to over 2 tonnes depending on the model. And they are improving all the time.
Quote:
Originally Posted by Mustang_Boss
(Post 5478740)
My <2KVA Inverter battery weighs ~50Kgs. with this as a base line, a 60 KV EV car would need 30 batteries and would end up weighing 1500 Kgs. To hold such heavy battery, the shell must go up in weight and would push the car into 3000 odd kgs territory.
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The inverter battery is lead acid type and weights so much more than Lithium ion battery. The typical EV battery weighs close to 10kg/kw. But EV needs other heavy components like AC-DC, DC-DC, DC-AC converters and add to the overall increase in weight.
By the end of this decade most EVs will come with smaller batteries.
There are advancements happening in energy density which is at a slow linear pace. A 2021 Model S Plaid version has 18650 cell that have 20% increased capacity compared to the 2012 Model S 18650 cell. So in 10 years its only 20% better. Yes, the cycle life and charge time has also improved but you still need big battery packs.
Now battery companies are putting funds into developing batteries that can charge several times faster. Ola for example has invested in a Israeli start up StoreDot which has has sent battery samples already.
With StoreDot battery a car can charge at about 160km range in 7 minutes for a car with 40kwh pack charging at @350kw charger vs the Nexon Max/XUV400 which also have 40kwh packs which take about 30 minutes to do the same.
StoreDot as target of 2 minutes charge time for 160km range by 2030. Just imagine having a charger at every toll booth which are currently 50km apart and in 30 seconds it can put about 50km of range, with some sort of automation that charges the car by itself when you slow down at the toll booth with induction charging or with a Bot charging.
This coupled with arrival of solid state batteries means smaller batteries can be used.
Quote:
Originally Posted by Mustang_Boss
(Post 5478740)
On a lighter note, :uncontrol My <2KVA Inverter battery weighs ~50Kgs. with this as a base line, a 60 KV EV car would need 30 batteries and would end up weighing 1500 Kgs. To hold such heavy battery, the shell must go up in weight and would push the car into 3000 odd kgs territory.
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Your inverter battery weighs 50kg because its a flooded lead acid battery, with the liquid weight alone at 15kg or more. So you cannot use thay as baseline.
Quote:
Originally Posted by Mustang_Boss
(Post 5478740)
On the contrary, major EV manufacturers place the battery packs lower and a significant amount of metal is used in protecting the battery packs from external elements, which is the primary reason.
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That is why EVs like the 2023 Model Y has a structural pack, 4680 cells and blade style cells enable the batteries to act as structural component.
Quote:
Originally Posted by vinya_jag
(Post 5478533)
Who on earth would want their pickup truck to accelerate to 100 in less than 3 seconds? Cargo would simply roll off from its back :D
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No person in their right mind would get a huge, Hummer as a practical vehicle. It costs 110k USD and for the price you could get a Ram 3500, Ford F-450 Superduty or a Chevrolet Silverado 3500 HD. With all options ticked. Heck these are more luxurious than some Mercs these days. Meanwhile the Hummer's base price is 110k. Though they are launching a cheaper EV2 model, it just isn't nearly as good as the other internal-combustion options.
It has a 5 ft bed mounted high up. This is no practical vehicle, just a rich person's weekend toy. The bed will probably never see any real use on any of these Hummers.
Shouldn't the lighter drivetrains of EVs balance the rise in curb weight caused by the battery pack?
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