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Comment by Spivak | Hacker News Reader

According to Tesla it takes 1h15m for a full charge. If you don't happen to be around a supercharger and have to use a 240v outlet you're looking at 9.5h for a full charge.

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Superchargers are not used to fully charge cars, because it's faster to stay lower in the battery -- supercharging is very slow for the last 20%. For this reason, superchargers are placed closer together than the maximum range of the car.

So no, supercharging does not take hours.

What's especially cool about this is that most homes in the U.S. have a 240v outlet in or near the garage, meaning it's easy to recharge while visiting friends or family.

Is that really true? What for?

I'm remodeling a house and putting in 240 just for the dryer an an unusual French range. Why would I need that in the garage? I certainly won't have that long an extension cord.

Dryers are often in the garage or in the small room adjacent to the garage that we called the "service porch" when I was a kid. I think it's because the garage is a good place for the main junction box (near the street, where the main power lines are, but indoors so creepers don't mess with it), and since 240-volt wiring is thick and expensive, it's cheaper to put any 240-volt outlets near the junction box.

QED.

So I'm going to know to unplug a dryer and expect my friends to be cool with that? And that plug is plain out in the visible, easily accessible areas and not hidden behind a heavy dryer?

People often don't have a dryer in the garage, but it's common enough that they'll have the plug there anyway.

I've owned half a dozen houses including new construction and never had a 240 outlet in the garage.

I wonder if it's a regional thing. My experience is US West Coast. The dryer is a source of waste heat, which out here is usually undesirable, so it makes more sense to put it in an extremity of the house where the heat can easily escape. I could imagine that other areas of the country might be more likely to view extra heat as a good thing.

For your lathe and vertical mill :-)

I'd rather have 208V (three phase) for that. Makes it easier to set up a variable frequency drive.

I want your garage.

It's dirt simple to add, as the garage is usually where the distribution box is anyway. And lots of tools (and now, electric cars) can take advantage of 240.

But the theory was that it's easy to charge when visiting friends/family because they'll already have it.

Of the houses I've lived in, and the ones of my friends, I'd say ~75% of them have 240 outlets in the garage that were there from the start, usually for the dryer. FWIW.

> And lots of tools (and now, electric cars) can take advantage of 240.

Off topic: That's interesting to know. In Europe (UK) where 240V (well more like 230V these days) is the standard, it's not uncommon to see professional workmen using step-down boxes and 110V power tools for safety reasons.

Really? I have never heard of that in Austria. All power tools use 230V. I've never seen or heard of a 110V tool that's on sale in Europe.

I could imagine that some professional might use a specialized tool in a niche where only a 110V version is available -- but I've never heard of that either.

The safety aspect sounds odd -- 230V is not that dangerous, especially considering that ground fault circuit breakers are mandatory. Accidentally touching a live 230V wire doesn't really hurt that much.

I guess it might just be a UK health and safety thing. Like you I've touched 230v a couple of times as a kid but can't say it's exactly pleasant.

This blog post lists the reasons professional builders in the UK could use 230v and an RCD but generally dont.

https://www.its.co.uk/blog/buying-guides/what-is-110v-do-we-...

Thanks for the link!

It looks like there's another important safety feature: the center of the output side of the transformers is connected to ground --> this means that you have two phases that both have only 55V to ground.

I imagine that accidentally touching an exposed wire with a voltage difference of 55V is a lot less dangerous than 230V.

I love HN. You learn new stuff every day.

you richer. us poor folk quite often put our laundry machines in the garage.

Still not convinced that there's an extra, easily accessible 240v plug that I can just plug my car into across most of my friends/family.

Certainly no one in an apartment building!

yeah, unplugging a community dryer at an apartment building to charge your fancy car probably wouldn't go over too well anyway.

someone needs to create self-driving mobile supercharging units - just call one up to meet you somewhere

"fancy car" -- EVs are available in all price ranges?

yeah I was mostly joking, although I couldn't afford one. The last vehicle I bought was a 1993 Ford Explorer - it was worth it because I got to learn how to replace an alternator. Crackheads eventually stole it. Next vehicle will be a pre 1996 mercedes turbodiesel so I don't have to get it smogged in california (poor people problems)

Hey Jim, would you please unplug your clothes dryer so I can charge my car?

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