[serf]

its less hard than you'd think unless you're really going for long range.

for my sailboat I am getting rid of a 300lbs diesel and a 30gallon fuel tank with a 45lbs PMAC.

That means I have opened up about 465lbs for batteries.

Now, with a sailboat you're never truly out of range -- but the point stands : these things are so much lighter than ICEs on average that there is a lot of opportunity even with battery weight as it is (and it's getting better daily).

[kpil]

I guess there's always the risk for a rig failure.

I looked a bit on doing the same, but came to the conclusion that it will be expensive to fulfil racing rules requiring the boat to be able to maintain speed for 5 hours ie around 25-30 NM range.

As it is now, I have about 500 NM diesel range on my boat, which is basically 3-4 days continuous runtime. Cutting it down to 25nm and 5 hours requires minimally 100kWh.

For a blue water boat, 500 NM is not quite acceptable, but can be fixed with jerrycans for a couple of dollars. An all electric blue water boat would clock in at an unrealistic 2MWh of batteries with a weight at least 20 metric tonnes. 10x the load capacity of my boat.

[dieselgate]

> there's always the risk for a rig failure.

Don't forget rudder and keel - especially if sailing off the coast of western europe...

[BobaFloutist]

This is silly, but I've also wondered if you could make a boat that can anchor and recharge batteries from ambient current, sort of like stationary regenerative braking. I'm sure it would take way too long to be worth it, but it was a fun idle thought.

[dieselgate]

Perhaps the paddle wheel[0] will interest you, the spinning is used to calculate the velocity of the boat. Probably some other propeller or similar would be more practical - like a kicker motor that's easily lowered over the side. Just spitballing. I don't think it'd be worth it considering solar options. Even wind generators are not "super efficient" in comparison but I don't have data.

[0] https://www.westmarine.com/bg-h3000-paddlewheel-sensor-w-pla...

[BobaFloutist]

I'm sure it wouldn't be worth it, because otherwise people would be doing it, it just seemed like a cool way to supplement solar or even to allow for indefinite underwater drones. Like, imagine a deep-sea research drone that could spit out an anchor and recharge whenever the battery got low. Almost certainly a case of "Cool, wouldn't really work well"

[lazide]

Uh, car batteries are much heavier than most ICE’s. The curb weight on teslas’s are crazy high.

BYD can be lighter because they skip on safety gear and proper structural elements - in my experience.

[dotancohen]

  > BYD can be lighter because they skip on safety gear and proper structural elements - in my experience.

I'd love to hear more about your experience with BYD. The ex just bought one and my kids ride in it daily. I helped negotiate the sale - I drive a Tesla and I'm very happy with the BYD.

[lazide]

Brazilians got a bunch of them and they are super common in Brazil. Also common - broken suspension parts from driving them in Brazil.

Also, the only cars I’ve ever ridden on that the top of my head literally touches the headliner while sitting in the back seat. Other than that, they seem good?

[dotancohen]

Great to know, thanks. Israeli roads are typically well maintained, but I'll keep an eye out for suspension damage.

In this Atto 3, I've ridden in the back a few times and my head does not touch the headliner. I'm 170cm.

[lazide]

Yeah, I’m 182+ cm, so a bit bigger. It still surprised me. BYD Dolphin if I remember was the worse.

The suspension issues seem like a common theme though, they aren’t built as sturdily as most cars on that front.

[cyberax]

Top-of-the-line NMC cells have energy density around 250Wh/kg at the pack level. The newer solid-state batteries can reportedly increase this to 400Wh/kg.

So a reasonable 75kWh battery pack is going to weigh around 300kg and in future around 200kg. This is... not a lot, actually. To a point where shaving off 20-30 kg from the electric motor weight is going to result in a noticeable performance/price difference.

Teslas also don't have "crazy" weight. Model 3 is 1700kg and a comparable (in size) Ford Focus is 1300kg.

[lazide]

If you stop cherry picking the lightest Tesla, you’ll see what I mean.

400 kg == 881 lbs, and that is their lightest model with lowest range.

[cyberax]

Model 3 LR with 360 miles of range is 1820 kg. Still nothing crazy.

[lazide]

That is over 4K lbs, and more than an older model full sized Toyota Tundra.

Newer model Tundras are over 5k lbs, but that is also crazy.

[bjelkeman-again]

BMW M3. Curb Weight: 3988 lb [1]

Tesla Model 3. Curb Weight: 3721 lb [2]

[1] https://www.caranddriver.com/bmw/3-series

[2] https://www.caranddriver.com/tesla/model-3

[lazide]

The Model 3 performance model (more equivalent to the M3) weighs over 4K lbs. The model you are quoting is the lowest range and lightest of all Teslas.

The Tesla model S (actually more equivalent to the M3) is over 4500 lbs [https://www.edmunds.com/tesla/model-s/2026/features-specs/].

No one is realistically saving weight by switching to batteries. Because batteries are heavy for the energy and gasoline is hella energy dense.