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Comment by eljimmy | Hacker News Reader

I've wanted a Tesla for a while, but being someone who repairs and maintains their own car, I can't see myself ever buying one as they seem heavily opposed to allowing anyone but themselves to work on their cars.

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You should probably not get a new car at all, they are all going that way. With electric/hybrid cars it's probably a good idea, there's a lot of current in those batteries.

Yup, last I checked the P90DL was around 500kW(!) at peak, that's 1,250A @ 400V.

Someone accidentally steps on the brake pedal while your near a HV line(400V can jump a bit) to one of the two motors? Yikes.

The Ludicrous version was enabled by fancy computer-controlled pyrotechnic fuses, because traditional melty-wire fuses have trouble past about 1200A. I think the new ones are good for up to 1500A.

Yeah, I was being a tad conservative. Either way that's a hell of a lot of power.

I'm surprised we haven't seen someone killed yet with a few of the battery pack teardowns that's happened.

I think the (very small) mismatch between your numbers and the 1500A figure may be a partly due to power going beyond 500kW, and partly due to voltage sag when drawing that much current. In any case, I didn't even mean that to be a correction, just an interesting related note.

As for people getting killed, I think the pack is hard enough to get into that people who don't know what they're doing are mostly discouraged before they get to the dangerous part. Maybe.

The Tesla has contactors in the battery that isolate the HV and a facility to lock them out - and they'd better be reliable even if someone accidentally steps on the brake pedal and the car's in pieces, because rescue workers have to rely on them in order to avoid electrocution when extracting people from crashed and mangled Teslas.

Besides, a lot of the failures are in low-voltage systems like door handles that are covered by a much shorter warranty than the drivetrain and HV.

There are two wiring loops you can cut which will cut power to those contactors and isolate the battery. If the car is sufficiently mangled, the first responders' first order of business will be to cut those loops, which will render the car safe no matter what controls people activate.

But if you haven't cut those loops and you're taking the car apart and haven't isolated things yourself, there's nothing preventing the car from closing those contactors and energizing the high-voltage system while you're elbow-deep in it.

Not quite...

When you step on the brake(with weight in the seat) you can hear the HV contactor engage(it's a soft thunk). In the case of emergency workers there's one of 3 specific places they must cut through in order to close the contact, otherwise the car is live.

I think the chances of some random joe forgetting to safe the system are higher(I'm just doing a door repair, I don't need to safe the system).

A standard car weighs 4000 lbs, that's a lot of weight to crush you if it falls on you while you're working on it.

People shouldn't be allowed to go under vehicles to repair them. In fact changing a tire with a jack is very dangerous too.

Oh come on now.

Your car doesn't go from weighing light as a feather to 4000lbs at the speed of light when two pieces of metal that you can't see connect.

There's a reason you should have a healthy respect of high voltage lines, there's no visual indicator that they are energized. At 400V anything that's unshielded will also jump a non-trivial distance.

History keeps repeating itself. That is what they said about those new fuel injected motors and control systems. It's just lag as the knowledge of how to fix new things spreads to the aftermarket. The stories about the Prius/Toyota battery pack corrosion and the DIY fix (instead of a complete battery pack replacement per Toyota standard operation) are an example of this. There is always a group that resists change and says it's the end and then within a few years, people adapt and figure out how to fix things all the same.

Admittedly, if completely locked out of the control system, what Tesla is doing may be more effective at blocking the aftermarket. But at some point, someone will just rip out the whole processing unit and replace it with a homegrown solution. The refrain has been "oh, all these sensors and who knows and ...". But the aftermarket keeps getting smarter.

There is a bit of evolution going on in batteries for RVs (caravans) and boats at the moment. Everyone wants to move to LiFePo batteries but most of the charging systems onboard are designed for traditional lead acids. Most lead acid chargers use a complex 3-4 stage charger. Lithium-ion is much simpler, 3.6V/cell until full. But actually getting a charger that will do this simple job has proved to be quite difficult.

People are starting to learn and there are still a lot of hold outs who believe charging Lithium-ions will burn your boat/RV/car down unless you are super, extra cautious.

I am not sure the fuel injection analogy will hold up here. There's nothing in a fuel injected car that will kill you unless you shove your arm into an exposed engine and try to run the starter or something, in which case you'd probably need two people and you'd have to be dumb enough to have left the battery connected. And even then you'd probably survive despite your crushed or amputated arm.

Electric cars are easily very lethal just by touching the wrong thing, or accidentally piercing a battery pack.

Working on vehicles has always been dangerous when they weigh 2,000+ pounds and are often supported by flimsy equipment. I don't disagree that batteries are lethal but it's just one more thing in a long list of things that can kill you while working on cars.

I can't imagine wheels/tires, brakes, and suspension disappearing from future cars. That type of maintenance is something that can save you hundreds, if not thousands of dollars in repair if you learn to do it yourself.

Ford Focus seems pretty maintainable as far as I can tell. And there seems to be plenty of competition there...

>I've wanted a Tesla for a while, but being someone who repairs and maintains their own car, I can't see myself ever buying one as they seem heavily opposed to allowing anyone but themselves to work on their cars.

Do you also watch an old Bakelite valve operated UHF television because Samsung says you can't open up their 70" OLED Flatscreen without voiding the warranty? Valve TVs were always burning out and needing repair. Much like internal combustion engine vehicles.

If its a hobby, sure, buy a '66 Mustang. Otherwise "I buy internal combustion engines and transmissions, rather than electric cars, so that I can save money on repairs and maintenance" seems somewhat problematic.

That seems to be the fate of most every consumer goods, isn't it?

The reality is that car repair is going to be a thing of the past. When Cars are nothing but an electric motor, chassis, and battery, there's nothing left to fix. Electric motors are orders of magnitude more reliable than internal combustion.

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