[darth_avocado]

> load is a really small factor in EV range.

That is just plain wrong. There is a reason why all EV companies, including Tesla obsess over energy density, and it’s because load is one of the biggest factors that affects range.

Forget EVs, load also affects range for traditional Semis. Do you seriously think an empty semi and one with a shipping container on the tow, would both have the same range?

[masklinn]

> That is just plain wrong. There is a reason why all EV companies, including Tesla obsess over energy density, and it’s because load is one of the biggest factors that affects range.

Energy density is energy per unit of volume. Every company obsesses over that because volume is the limiting factor for getting energy in a vehicle.

Energy specificity (energy by unit of weight) is only relevant to planes, no EV company gives much of a fuck about it. Would they like it if batteries were lighter? Absolutely. Would they take a heavier battery if it was denser? In a heartbeat.

> Forget EVs, load also affects range for traditional Semis.

There are major differences between a traditional prime mover and an electric one: electric motors don’t have the divergent torque/power curve of ICE, or the choked low end, and moving a load is kinetic energy which EVs can largely convert back into electricity instead of losing it entirely. So the inefficiencies related to getting the load moving largely go away.

[darth_avocado]

Well arguing load isn’t a factor and the real limitation is the volume is still wrong. EVs aren’t infinite in size and real world constraints exist. At the end of the day, your semi cannot be 90% battery and ferry only a pallet of chips.

Total energy spent on moving an object by a distance is still proportional to the mass of the object. So if you’re absolutely spending more energy hauling 10000lbs vs 100lbs.

The only point where the cargo is relatively immaterial to the range is when it is a very small percentage of the actual weight of the vehicle. But that doesn’t mean the vehicle is efficient. It’s just that now you’re spending more energy hauling the battery itself than the cargo. Energy density matters in semis because companies want to spend less money hauling the battery itself than the cargo to make it viable.

Rivian an electric car company admits that towing will reduce your range. There’s a reason for that. https://rivian.com/support/article/how-does-towing-affect-ra...

[masklinn]

> Total energy spent on moving an object by a distance is still proportional to the mass of the object.

It is not. The energy spent to change momentum is proportional to mass. For mass to affect momentum you need a second order effect linking it to increased system losses e.g. a heavier plane needs more lift, which requires higher speeds, higher angle of attack, larger lifting surfaces, …, all of which increase drag, which is the primary way planes lose energy.

> Rivian an electric car company admits that towing will reduce your range. There’s a reason for that.

The reason is the increased resistances (air and rolling) from the trailer: https://youtu.be/UmKf8smvGsA

[fragmede]

Things being towed by a Rivan are going to be less standardized than what a semi is going to tow.

[matt-attack]

For long routes over level terrain it has almost no effect at all.

Sure to a commuter in stop and go traffic or city driving it might matter a bit but regen takes away the first order of magnitude.

Even climbing a hill is a bit of the same effect. To first order, you recover it on the back side of the hill coming down.