Charging Station Goes Boom, EV Won't Work: What Happens Next

https://www.caranddriver.com/news/a43065558/ev-charging-station-broken-what-happens-next/

by DocFeind • 3 years ago

19 10 3 years ago

Awelton• 3 years ago

I have driven both gas and diesel vehicles for over 20 years, from small cars to bulldozers, and had all different kinds of them fail spectacularly at the worst moments. I have got gas at places where they accidentally put diesel in the gas tanks, diesel from places that had water ingress, rods thrown through the side of the block 1,000 miles away from home, you name it. I don't own an electric vehicle but I don't think anyone that does is under the impression that they would be completely problem free. It seems strange to me that a couple hundred thousand cars burn to the ground ever year in the US but all the news stories focus on the handful of EV fires. I also find it suspicious that the slightest problems they have are simultaneously written about by dozens of news sites with nearly the same wording. I don't have any skin in the EV game, but it's hard not to notice the bias against them. It would be interesting to see where the money flows to and from in all this reporting.

dsfyu404ed• 3 years ago

It's news because it's happening to "good people".

Old stuff near the end of its life breaks, not news. New cars break, big news.

Some people have beef and get shooty in some low rent part of Detroit, not news. Some people have beef and get shooty with each other in some high rent suburb of Boston or SF, big news.

up2isomorphism• 3 years ago

The exact reason you think there’s a bias towards EV is be because you don’t drive them.

It is way too underdeliver is the main issue not its imperfections.

Veliladon• 3 years ago

Why can't the breaker just be reset like a house breaker? Shouldn't there be a physical switch in the fuse panel? Or if it's a consumable part that sacrifices itself like a regular fuse shouldn't it be user-replaceable? Being able to fix something roadside with a <$100 part seems to be easily achievable here.

londons_explore3• 3 years ago

Typically these breakers (usually explosive fuses) are single use. They aren't expected to ever break in the lifetime of the car, and sometimes aren't replaceable (ie. They're sealed in under glue inside the non-disassemblable battery).

The purpose of them is two fold:. They can save human life if you are an idiot and cut through high voltage wiring with a saw while the vehicle is powered up... In this case, they act like a GFCI.

They can also act like overcurrent protection devices, which can prevent massive electrical fires in the case of a short.

Normally there is also a contactor in the same current path. That is a software controllable switch. But the switch is relatively slow to turn off, and cannot turn off if the current flow is too massive - and in either case, the single use breaker will be used instead to prevent electrocution or a big fire.

tigeba• 3 years ago

I had a chademo fast charging station clamp on my car and refuse to let go, along with not actually doing any charging. They tried resetting the charger but nothing worked. It eventually timed out and gave up after 12 hours or so. No harm done to the car but quite annoying.

ksaj• 3 years ago

How long would you have been there waiting for it to let go if it wasn't a fast charger?

sentientslug• 3 years ago

You're more patient than I am. Physical methods would have been employed far sooner than 12 hours if it was my car.

londons_explore3• 3 years ago

This probably was caused by poor design of the charger.

For a huge overcurrent event to happen, some of the switching elements in the power converter failed (or their control logic did).

However, that is a reasonably foreseeable event. The charger should have been tested for what happens when each piece of the charger fails open circuit or short circuit.

It is perfectly possible to design control electronics which can detect the failure of any piece and adjust the control strategy of the other parts of the circuit to prevent damage to whatever is on the output.

londons_explore3• 3 years ago

This is the circuit used in most DC fast chargers:

https://www.researchgate.net/publication/261875419/figure/fi...

If any of the 6 transistors on the left fail, you simply turn off all of the other 5, and your car is safe.

If the bottom right transistor fails short, you will get an overcurrent event in the top right transistor, and must turn it off before it blows up - which will typically need to be done in nanoseconds.

If the bottom right transistor fails open, the top right transistor will blow up unless you have a backup body diode across the bottom right transistor.

If the top right transistor fails open, nothing bad happens.

If the top right transistor fails short, you need to immediately turn on all the other transistors, and deliberately blow a fuse on the AC input (this will be destructive - every transistor will fail most probably).

Charging Station Goes Boom, EV Won't Work: What Happens Next

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