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Modern vehicle weigh multiple tons, what's a half-ton battery really matter? Also much of the weight is carbon and oxygen. LiFePO4 also (obviously) is substant

by coryrc 5y ago

Modern vehicle weigh multiple tons, what's a half-ton battery really matter? Also much of the weight is carbon and oxygen. LiFePO4 also (obviously) is substantially iron and phosphorous. Li-Ion battery production had been growing at double-digit percentage for decades. I think they've proven you wrong many times over. Finally, electric cars charge at ~96% efficiency, while hydrogen is something like 40%. I, for one, am not interested in paying 3x per mile.

rewma 5y ago
> Modern vehicle weigh multiple tons, what's a half-ton battery really matter? The Tesla Model S weights about 2100kg. The Tesla Model S battery weights about 540kg. This means that a 1500kg car is forced to pack an additional 540kg to be able to store energy. That's an additional 30% of the mass that you need to accelerate and brake. People do care about that. In the very least, the battery mass is responsible for an effective drop in energy efficiency of around 30% just to cart someone around. > Finally, electric cars charge at ~96% efficiency, while hydrogen is something like 40%. I, for one, am not interested in paying 3x per mile. This claim has little substance and credibility. For starters, if you factor in how much additional energy you need to waste just to pack along a massive half ton battery, you'll eventually realize that the effective energy waste of a EV is not much different than the hydrogen one. I mean, the point of a EV is not to have it parked on the driveway, charge a battery, and proceed to boast about how that was very efficient. Your goal is to move around, and moving that massive half ton beast of a battery along with you wastes a lot of energy too. Also, battery efficiency is around 80%, which naively sounds a far improvement over fuel cell's lauded 40% efficiency. However, a Li-Ion battery weights half a ton and represents around 1/3 of a EV's mass, which also requires energy to be moved around. For reference the fuel cell of a Toyota Mirai is only 40kg, less than the weight of an adult passenger. Once you do your math you'll quickly notice the effective energy use is not that different. And then there's the cost argument. The typical back-of-the-napkin figure for how much EVs cost to run is around 500€/year. Even if you bump that up to twice the cost, that price is eclipsed by the huge markup that you're already paying for an EV. I mean, a Tesla Model S costs about a century worth of energy bills before it even gets it's tires dirty. Playing the frugality card with the current batch of EVs lacks any credibility and is, at best, being penny wise and pound foolish.
- bostik 5y ago
  > This means that a 1500kg car is forced to pack an additional 540kg to be able to store energy. I think this is the wrong angle to look at the issue. A 2100kg EV requires 25% of its total mass to support the energy storage, generation and transfer in order to provide a range and performance profile people are generally happy with. What is the fraction for a new ICE vehicle with similar profile? The combustion engine weighs... how much? Then add the weight of a 60% full fuel tank to allow for roughly the average deadweight haul between refills. Then include the weight of the exhaust system. And finally, we have to include the weight of the drivetrain. How much of the total weight in an ICE is dedicated to power transfer from engine to wheels? How much in a modern EV? Energy storage and generation is only a part of the picture, getting it to the wheels is what makes a car actually perform its function. We should include these numbers to get a meaningful comparison.
- IshKebab 5y ago
  > In the very least, the battery mass is responsible for an effective drop in energy efficiency of around 30% just to cart someone around. It's not nearly as simple as that because electric cars have regenerative braking, and because the energy doesn't all go into acceleration. A lot (probably most, depending on how you drive) goes into wind/rolling resistance at a constant speed and that doesn't depend much on mass.
  - glogla 5y ago
    Toyota H2V (Mirai) has a small battery that serves as a buffer for the fuel cell, and it can also regen brake into it. I'm still convinced hydrogen is scam greenwashing natural gas, though.
- JProthero 5y ago
  > Finally, electric cars charge at ~96% efficiency, while hydrogen is something like 40%. >> This claim has little substance and credibility. The efficiency of hydrogen fuel cell vehicles versus battery vehicles is considered in some detail in this video [1]. The conclusion [2] is that, in the best case, the energy efficiency from power generation to road for existing or near future hydrogen fuel cell vehicles is about 25%, compared to about 65% for typical existing battery vehicles. [1] https://www.youtube.com/watch?v=f7MzFfuNOtY https://www.youtube.com/watch?v=f7MzFfuNOtY [2] https://www.youtube.com/watch?t=651&v=f7MzFfuNOtY https://www.youtube.com/watch?t=651&v=f7MzFfuNOtY
jazzyjackson 5y ago
> Li-Ion battery production had been growing at double-digit percentage for decades. I think they've proven you wrong many times over Mold in a petri dish grows at an accelerating rate, until it doesn’t My conjecture is that there’s not enough lithium/etc in the world to store the energy the transportation sector requires small cars, passenger trains, sure. but freight is a different animal. we’ll see.
- Tuna-Fish 5y ago
  It's not a good idea to conjecture and argue from total ignorance. There are commonly used battery chemistries, such as LiFePO4/graphite, that simply do not use any scarce resources.
  - theduder99 5y ago
    welcome to hackernews. also why don't the car battery manufacturers go the lifepo4/graphite route?
    - Tuna-Fish 5y ago
      Other materials are mildly better and not too scarce. Tesla is moving some of it's production to LFP, but that's probably mostly because they want to scale up production faster than nickel mining can scale.
    - mastax 5y ago
      They do. Everyone in China is using them. Tesla is starting to use them outside of China as well.
  - deleted 5y ago
    [deleted]
- lukeschlather 5y ago
  Lithium is not a scarce resource. This is pretty obvious because when looking at commodity prices lithium is measured in $/metric ton rather than actually scarce elements like gold where the price is in $/troy ounce.

by coryrc 5y ago

rewma 5y ago

> Modern vehicle weigh multiple tons, what's a half-ton battery really matter? The Tesla Model S weights about 2100kg. The Tesla Model S battery weights about 540kg. This means that a 1500kg car is forced to pack an additional 540kg to be able to store energy. That's an additional 30% of the mass that you need to accelerate and brake. People do care about that. In the very least, the battery mass is responsible for an effective drop in energy efficiency of around 30% just to cart someone around. > Finally, electric cars charge at ~96% efficiency, while hydrogen is something like 40%. I, for one, am not interested in paying 3x per mile. This claim has little substance and credibility. For starters, if you factor in how much additional energy you need to waste just to pack along a massive half ton battery, you'll eventually realize that the effective energy waste of a EV is not much different than the hydrogen one. I mean, the point of a EV is not to have it parked on the driveway, charge a battery, and proceed to boast about how that was very efficient. Your goal is to move around, and moving that massive half ton beast of a battery along with you wastes a lot of energy too. Also, battery efficiency is around 80%, which naively sounds a far improvement over fuel cell's lauded 40% efficiency. However, a Li-Ion battery weights half a ton and represents around 1/3 of a EV's mass, which also requires energy to be moved around. For reference the fuel cell of a Toyota Mirai is only 40kg, less than the weight of an adult passenger. Once you do your math you'll quickly notice the effective energy use is not that different. And then there's the cost argument. The typical back-of-the-napkin figure for how much EVs cost to run is around 500€/year. Even if you bump that up to twice the cost, that price is eclipsed by the huge markup that you're already paying for an EV. I mean, a Tesla Model S costs about a century worth of energy bills before it even gets it's tires dirty. Playing the frugality card with the current batch of EVs lacks any credibility and is, at best, being penny wise and pound foolish.

bostik 5y ago
> This means that a 1500kg car is forced to pack an additional 540kg to be able to store energy. I think this is the wrong angle to look at the issue. A 2100kg EV requires 25% of its total mass to support the energy storage, generation and transfer in order to provide a range and performance profile people are generally happy with. What is the fraction for a new ICE vehicle with similar profile? The combustion engine weighs... how much? Then add the weight of a 60% full fuel tank to allow for roughly the average deadweight haul between refills. Then include the weight of the exhaust system. And finally, we have to include the weight of the drivetrain. How much of the total weight in an ICE is dedicated to power transfer from engine to wheels? How much in a modern EV? Energy storage and generation is only a part of the picture, getting it to the wheels is what makes a car actually perform its function. We should include these numbers to get a meaningful comparison.
IshKebab 5y ago
> In the very least, the battery mass is responsible for an effective drop in energy efficiency of around 30% just to cart someone around. It's not nearly as simple as that because electric cars have regenerative braking, and because the energy doesn't all go into acceleration. A lot (probably most, depending on how you drive) goes into wind/rolling resistance at a constant speed and that doesn't depend much on mass.
- glogla 5y ago
  Toyota H2V (Mirai) has a small battery that serves as a buffer for the fuel cell, and it can also regen brake into it. I'm still convinced hydrogen is scam greenwashing natural gas, though.
JProthero 5y ago
> Finally, electric cars charge at ~96% efficiency, while hydrogen is something like 40%. >> This claim has little substance and credibility. The efficiency of hydrogen fuel cell vehicles versus battery vehicles is considered in some detail in this video [1]. The conclusion [2] is that, in the best case, the energy efficiency from power generation to road for existing or near future hydrogen fuel cell vehicles is about 25%, compared to about 65% for typical existing battery vehicles. [1] https://www.youtube.com/watch?v=f7MzFfuNOtY https://www.youtube.com/watch?v=f7MzFfuNOtY [2] https://www.youtube.com/watch?t=651&v=f7MzFfuNOtY https://www.youtube.com/watch?t=651&v=f7MzFfuNOtY

jazzyjackson 5y ago

> Li-Ion battery production had been growing at double-digit percentage for decades. I think they've proven you wrong many times over Mold in a petri dish grows at an accelerating rate, until it doesn’t My conjecture is that there’s not enough lithium/etc in the world to store the energy the transportation sector requires small cars, passenger trains, sure. but freight is a different animal. we’ll see.

Tuna-Fish 5y ago
It's not a good idea to conjecture and argue from total ignorance. There are commonly used battery chemistries, such as LiFePO4/graphite, that simply do not use any scarce resources.
- theduder99 5y ago
  welcome to hackernews. also why don't the car battery manufacturers go the lifepo4/graphite route?
  - Tuna-Fish 5y ago
    Other materials are mildly better and not too scarce. Tesla is moving some of it's production to LFP, but that's probably mostly because they want to scale up production faster than nickel mining can scale.
  - mastax 5y ago
    They do. Everyone in China is using them. Tesla is starting to use them outside of China as well.
- deleted 5y ago
  [deleted]
lukeschlather 5y ago
Lithium is not a scarce resource. This is pretty obvious because when looking at commodity prices lithium is measured in $/metric ton rather than actually scarce elements like gold where the price is in $/troy ounce.