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0 pointswongarsu2y ago0 comments

Yes, to get more range you need more batteries, and those increase your weight meaning you need more batteries. But those increase your weight, so you need even more batteries. The tyranny of the rocket equation.

Not really specific to this dual-chemistry though, the same holds true for normal EVs and for gasoline-powered cars.

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_ea1k2y ago

It is a bit different from the rocket equation. The impact of weight on energy consumed per mile in a car is not particularly large. You can add hundreds of pounds and the impact will be negligible.

adrianN2y ago

At least if you have regenerative brakes. Otherwise weight matters in stop and go traffic quite a bit.

fragmede2y ago

Are there any EVs without regenerative brakes? As soon as that technology matured, given how much geopolitics is about energy, it's surprising to me we didn't mandate it's usage.

_ea1k2y ago

With EVs, they all have regen, but also, efficiency for range purposes primarily matters at highway speeds. There isn't a lot of stop and go there.

keenmaster2y ago

True, but the difference here is that the second battery isn’t even used most of the time, and if it was it would die quickly.

wongarsuOP2y ago

But is that really substantially different from somebody keeping their gas tank always at least half full, or making normal short-range trips with the long-range version of a Tesla?

Everyone already tried selling EVs with smaller batteries. The might be more efficient on paper but they don't sell. Turns out that trips people take once in a blue moon are still important to them, so a battery tuned to making that possible once in a blue moon sounds very useful.

RcouF1uZ4gsC2y ago

> But is that really substantially different from somebody keeping their gas tank always at least half full, or making normal short-range trips with the long-range version of a Tesla?

A gallon of gas weighs around 6 pounds. A car usually has less than 20 gallon capacity. Keeping it half full would mean you keep 10 gallons which is 60 pounds. Even if you kept it full all the time, it is 120 pounds. That is going to be a lot less than any sizable battery ( theTesla Model 3 battery weighs around 1000 pounds).

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_ea1k2y ago

It is a bit different from the rocket equation. The impact of weight on energy consumed per mile in a car is not particularly large. You can add hundreds of pounds and the impact will be negligible.

adrianN2y ago

At least if you have regenerative brakes. Otherwise weight matters in stop and go traffic quite a bit.

fragmede2y ago

Are there any EVs without regenerative brakes? As soon as that technology matured, given how much geopolitics is about energy, it's surprising to me we didn't mandate it's usage.

_ea1k2y ago

With EVs, they all have regen, but also, efficiency for range purposes primarily matters at highway speeds. There isn't a lot of stop and go there.

keenmaster2y ago

True, but the difference here is that the second battery isn’t even used most of the time, and if it was it would die quickly.

wongarsuOP2y ago

But is that really substantially different from somebody keeping their gas tank always at least half full, or making normal short-range trips with the long-range version of a Tesla?

RcouF1uZ4gsC2y ago

> But is that really substantially different from somebody keeping their gas tank always at least half full, or making normal short-range trips with the long-range version of a Tesla?

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