Article in October 23 The Economist about EV maintenance

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Bouldergramp

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Somewhat interesting title:

"Inside the garage of the future
Servicing and repairing electric cars requires new skills
Many workshops will be out of a job"

But this is odd,
"The box is a 93kwh battery. The chassis belongs to a 260kph Taycan, Porsche’s first fully electric vehicle (ev). Cables, bright orange in warning, snake across it to a pair of motors and other electronic gubbins. As many a mechanic, professional and amateur, knows, fiddling with the 12v system of a typical internal-combustion engine (ice) can give you a nasty electrical jolt. But this battery delivers 800v. Though it is fitted with safety systems, that is enough for a knockout punch that could kill you."

I don't think fiddling with a 12v system is dangerous. I suppose if a person grabbed a spark plug lead they might feel an electrical jolt if the engine is running but I can't even see the spark plugs on my Honda Odyssey.
 
In the case of 12V the problem is not the voltage but current. A direct short of the battery (e.g. dropping a tool across the contacts) can carry thousands of amps, cause grievous burns and send molten metal flying or even cause an explosion, which is not a good thing when the "bomb" contains concentrated sulfuric acid.
 
Spark plug leads, OTOH, carry hundreds or even thousands of volts, but very little amperage. I've felt that "jolt" myself, but while it's quite unpleasant, it wouldn't usually be life-threatening.
 
Agreed on the hazards of 12V batteries. I'll just add that electrocution is always a matter of current, but with higher voltages it is easier to reach a lethal current level. Eg, lIghtning contains millions of volts but the current is minimal. The danger there is mostly from the intense heat generated and the shock that accompanies that heat, which is what causes thunder. 120V AC is almost too low to be fatal unless you lower your resistance to ground by standing in water, etc.
 
When I was a kid, I came into contact with 120 volts a few times. Once, I was working behind my old console-style home stereo, splicing in some extra speakers. Yes, you guessed it. I actually touched the wire twice, to make sure I didn't imagine it. I also discovered, at a younger age, that an electric cattle fence can shock you through a blade of straw. Lotta voltage, there.
 
goldbrick said:
Eg, lIghtning contains millions of volts but the current is minimal.


A typical lightning flash is about 300 million Volts and about 30,000 Amps. In comparison, household current is 120 Volts and 15 Amps. There is enough energy in a typical flash of lightning to light a 100-watt incandescent light bulb for about three months or the equivalent compact fluorescent bulb for about a year.

https://www.weather.gov/safety/lightning-power

Then there are rare "superbolts", roughly a million Amps.
 
Decades ago, I had a temporary assignment repairing classroom computers for the Los Angeles Unified School District. We had old standard-issue "teacher desks" for workbenches, and when we weren't out in the field, we were all in one big room, with an Office Machine Repair apprentice doing a rotation with us.

One OMR apprentice was working on a monitor (remember, this was decades ago, and all monitors were CRTs). She brushed up against the 12KV CRT "well." Thankfully, she wasn't injured, but the expression on her face was priceless.

Not long after that, I was working on a Commodore PET. It was plugged in at the time, and I brushed up against the 120V hot lead. No burns, and thankfully, the path to ground wasn't straight through my heart, but I did end up with some very sore forearm muscles for a few days.

The thing about 12V lead-acid batteries is that they have very low internal resistance. So they can very easily deliver enough current to arc-weld.
 
Also as a kid, I had a 12 volt battery in my room. (I had actually requested it for Christmas.) I had a pair of wires with small clamps on all ends (but lighter than jumper cables, IIRC) and I used to use the graphite from a pencil to make a crude but usable cutting torch.
 
LeftieBiker said:
Also as a kid, I had a 12 volt battery in my room. (I had actually requested it for Christmas.) I had a pair of wires with small clamps on all ends (but lighter than jumper cables, IIRC) and I used to use the graphite from a pencil to make a crude but usable cutting torch.
I had a 6v lead-acid battery in my room as a kid :shock: it powered an old AM truck radio(with a vibrator) and I used it to tune distant AM channels, I could easily get WLS out of Chicago and Saturday nights were reserved for WSM out of Nashville. Denver came in regularly, NYC was a bit harder to get, I seem to remember STL was also pretty easy to get, of course all only came in after dark.
 
I grew up in the CB Radio Era, so I had one of those - but only a moderately powered walkie talkie (sp?). I did also have an old multi-band radio as well, though, and I'd sometimes listen to shortwave broadcasts. With both of those I'd also take advantage of the nighttime "skip."
 
WLS, yes, how about WWVA in Wheeling West Virginia? old-time country music at its best. What do kids do these days to keep themselves awake at night and to learn about scratchy AM radio? (rhetorical question by the way....)
 
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