Lithium-Ion Batteries and others

[Stefan Mikes]

Were they still on DC

A transformer can only work with AC.

 

[Chargeride]

I am always amazed to hear of people being electrocuted in the States, you run 120V, that voltage shouldnt kill you, but it does, construction sites in the UK have to use ludicrously heavy 240-110 transformers, but people are still being killed.
There plenty of diy battery builders using 90V , you can stick your hands on
Such a battery that can supply hundreds of amps, but its very unlikely to stop your heart.
Funnily enough the two wire telephone feed that still goes to houses not using voip is 90V, they upgraded decades ago to make adsl internet work better over copper wires.
I got quite a shock on a hot day, my sweaty forehead touched a wiring block
And I got flashes in my eyes and a thump of a jolt as I was holding a 90v wire in my fingers at the time.
The current was tiny, but it can leap for a split second.

 

[Stefan Mikes]

I am always amazed to hear of people being electrocuted in the States, you run 120V, that voltage shouldnt kill you, but it does, construction sites in the UK have to use ludicrously heavy 240-110 transformers, but people are still being killed.
There plenty of diy battery builders using 90V , you can stick your hands on
Such a battery that can supply hundreds of amps, but its very unlikely to stop your heart.
Funnily enough the two wire telephone feed that still goes to houses not using voip is 90V, they upgraded decades ago to make adsl internet work better over copper wires.
I got quite a shock on a hot day, my sweaty forehead touched a wiring block
And I got flashes in my eyes and a thump of a jolt as I was holding a 90v wire in my fingers at the time.
The current was tiny, but it can leap for a split second.

I could tell you how one can stupidly kill themselves with a 9 V battery but you could actually try it...

 

[kevinmccune]

240 volt kettles? The US discovered in the 19th Century that 240 V countertop appliances are not safe. We bring 240 to the house with a ground halfway between. The 240 is for things like my water heater. For a few years, it would sometimes arc between the terminals of the lower heating element and trip the breaker. There was a bit of rust between the terminals. 240 has a peak of 336, which could sometimes arc between the terminals. I finally got tired of it and spent $7 on a new heating element.

Such arcing in a plug-in appliance could start a fire, so we use 120, peak 168, for ordinary plugs. Besides, 120 is much less likely to kill the person who touches the base of a bulb that's wired wrong. r

that's actually a problem with the new proposed 48 volts automotive systems,nasty shock and far above arcing threshold

 

[kevinmccune]

A transformer can only work with AC.

unless you use a "chopper"( seems inefficient) however the big advantage of AC is the diverse pressures availible with transformers. Our grid rural supply wires are 7200 volts however most new transformer installations are dual tap in case they switch to 14400 line voltage, the old high tensile copper conductors were almost invisible against the skyline, now those horrid Al conductors stick out like a sore thumb.

 

[Chargeride]

People get shocks off 12v car batteries, but its usually back emf off old school coils.
But those goddam retina burning arc lights that are killers, stupid voltages, dreadful tech.
So now we have blue light leds and its like driving past WW2 search lights at night.
People actually are wearing sunglasses at night, reddit is going postal about it and rightly so.

 

[spokewrench]

A transformer can only work with AC.

Then do you see my point? Edison and Westinghouse had for years used AC so they could distribute power at high voltage and at its destination step it down with a center-tapped 240 volt transformer. Was Berlin still on DC?

And why are the US, Japan, and Canada so far ahead of Europe? Europeans must like to be different. Some even speak French!

 

[kevinmccune]

People get shocks off 12v car batteries, but its usually back emf off old school coils.
But those goddam retina burning arc lights that are killers, stupid voltages, dreadful tech.
So now we have blue light leds and its like driving past WW2 search lights at night.
People actually are wearing sunglasses at night, reddit is going postal about it and rightly so.

hate those blasted things!

 

[spokewrench]

I am always amazed to hear of people being electrocuted in the States, you run 120V, that voltage shouldnt kill you, but it does, construction sites in the UK have to use ludicrously heavy 240-110 transformers, but people are still being killed.

In America, I think 3% of worker deaths are from 120 VAC. Skin resistance is pretty high, but that's per mm^2. If you're grabbing something metal, that's a large area of skin, which may be damp and salty. Footwear resistance may be high, but not if it's wet. Outdoor construction work can be especially dangerous because dampness can help current get through or past insulation. A nip from 110 could be much worse from 240.

 

[harryS]

I am always amazed to hear of people being electrocuted in the States, you run 120V, that voltage shouldnt kill you, but it does, construction sites in the UK have to use ludicrously heavy 240-110 transformers, but people are still being killed.
There plenty of diy battery builders using 90V , you can stick your hands on
Such a battery that can supply hundreds of amps, but its very unlikely to stop your heart.
Funnily enough the two wire telephone feed that still goes to houses not using voip is 90V, they upgraded decades ago to make adsl internet work better over copper wires.
I got quite a shock on a hot day, my sweaty forehead touched a wiring block
And I got flashes in my eyes and a thump of a jolt as I was holding a 90v wire in my fingers at the time.
The current was tiny, but it can leap for a split second.

The US analog telephone system ran on 48V lead acid. There are huge battery banks providing the power, with AC used to keep them charged, When the phone rings, the voltage is chopped to make the bells on the old phones work, and that's why we feel 90V. I spent years in telecomm in the USA.. Perhaps British Telecomm is different.

The 48V was deemed safe for most humans, but I believe a baby could get killed, When I was kid. we would have these one tube radio kits, where the plate voltage on the tubes was 48 to 90 volts. In scout camps, some kid thought it woukd be funny to sneak up on you and put the terminals on your butt. It was a shocker.

 

[Chargeride]

Yeah, we used to be 5Ov lead acid, kept the voltage for digital, even kept loop disconnect.
The 90v was to improve internet speeds over copper, it was only if you had the internet.

Huge rooms of washing machine sized lead batteries, open top, bubbling away.
The busbars in the main exchange were 10 12x2 inch copper bars bolted together, running through walls and feeding off to the racks.

1000amp detonating fuses, I blew a 300 amp with a knife cutting insulation.

I always imagined shorting the main bars with something like a crowbar, it would probably melt instantly.
50,000 amps..
I guess you had the same strowger.

 

[Chargeride]

In America, I think 3% of worker deaths are from 120 VAC. Skin resistance is pretty high, but that's per mm^2. If you're grabbing something metal, that's a large area of skin, which may be damp and salty. Footwear resistance may be high, but not if it's wet. Outdoor construction work can be especially dangerous because dampness can help current get through or past insulation. A nip from 110 could be much worse from 240.

I have been shocked so many times by 240V, I have one advantage, very dry hands.
I got a bolt from an unknown 240ac dual feed a few years ago, my hands were wet and I was lying on a wet floor that has soaked my clothes.
Holy crap that hurt, it was like someone jack hammering my spine.
Had to go home, went the docs, all seemed fine.
But that was a proper game over potential shock, worst Ive ever had.

 

[Stefan Mikes]

Why do you guys talk 240 V when all Europe including the UK is on 230 V?

 

[DaveMatthews]

I am always amazed to hear of people being electrocuted in the States, you run 120V, that voltage shouldnt kill you, but it does, construction sites in the UK have to use ludicrously heavy 240-110 transformers, but people are still being killed.
There plenty of diy battery builders using 90V , you can stick your hands on
Such a battery that can supply hundreds of amps, but its very unlikely to stop your heart.
Funnily enough the two wire telephone feed that still goes to houses not using voip is 90V, they upgraded decades ago to make adsl internet work better over copper wires.
I got quite a shock on a hot day, my sweaty forehead touched a wiring block
And I got flashes in my eyes and a thump of a jolt as I was holding a 90v wire in my fingers at the time.
The current was tiny, but it can leap for a split second.

It's only the ringing voltage on a phone line that is 90vac, the regular voltage is 48vdc to power the phone and talk.

 

[Mr. Coffee]

Voltage isn't generally what kills you in an electric shock, it is the current.

When you rub your stocking feet on the carpet to build up a charge and shock your friend that little spark is somewhere north of 1000 volts. Maybe up to 70_000 volts. But not many people are killed by that.

Switchboards - Fatal electric shock: what voltage causes death? - Metroid Electrical Engineering

How much current does it take to kill someone? A current of as little as 0.007 amps (7mA) across the heart for three seconds is enough to have a Fatal Electric Shock

www.metroid.net.au

 

[kevinmccune]

cattle have very low tolerance for electricity somebody told me sometimes voltage as low as 6 volts can do them in a thunderstorm with a tree strike used to regularly kill cows around here of course it a very high voltage , the total amperage and voltage from a lightning strike will peel the bark off of a tree and even explode the roots, last strike I had near the house peeled a tree exploded the roots and blew up underground ,when my skin started tingling and came into my house and destroyed a lot of electronics. some people seem to be human "lightning rods" read the case of the ranger in Shenandoah national park who was struck several times,he said the experience was like being scalded from the inside.If you are out in the open during a thunderstorm and feel your skin tingling and hair standing up hit the ground immediatly,one of my mentally challenged bosses had me running a metal drum roller during a thunderstorm don't rightfully remember now think I bailed when my skin started tingling,the roller didn't have a roll cage you just sat perched on top of the thing.
On the subject of cattle one of my uncles told the cows stopped drinking from a certain water trough,it seems the outside ground braid on the feeder cable was corroded through and the cows could sense the ground fault in the water trough the cable was fairly close to the water trough our dual feed house system 2x110 is very safe for a number of reasons.