For Science! Oct 28, 2022 3:36:54 GMT -5 a_muppet, kjay, and 1 more like this
Post by jen on Oct 28, 2022 3:36:54 GMT -5
It's interesting, and perhaps scary, to see some of the figures. The current stated, 1,400 amps would be a real problem if a faulty connection happened with just a parasitic resistance of just one ohm. That would have to dissiapate 1.96 kW of power (heat). Even at say 0.1 ohm, which is not untypical in normal wiring, it would be 196 W which is almost twice that of the old 100W lamp bulb. Remember how hot they used to get?
It's all safe until it goes wrong but such systems, at the moment, are in the provice of experts, not generally the home user. Some people do tinker
As an example, I replaced one of our storage heater mains switches. I found that, because of a loose connection, the high current flow had badly charred and blackened the the switch and surrounding area. This is only a few amps, not even tens or hundreds.
I feel I need to apologise a little for this one. Nerdy me has become just as guilty as the press lol. Although I am correct, further thinking puts this more in context. To get 1,400 amps through a 1 ohm resistor it would take a supply of 1,400 volts. Not the average home supply A supply of 240V would give a current of 240 amps through 1 ohm then across a short circuit, or with 115 volts, 115 amps.
Due to the limitations on mains electricity I cannot really see how anything near their claimed figures will be obtained at home, at least at mains voltages. It's really a question of energy supply so this rapid charging will only be available at properly designed sites (with their own power stations? ) I see the current home chargers are rated at around 32 amps. Perhaps overnight charging will always be the norm unless you have ready access to an industrial 3 phase supply?
Another nerdy entry - I looked at the power station list and saw the Hinckley Point B nuclear reactor was rated at 965 megawatts in 2020. A substantial output. With these advanced chargers giving a 5 minute charge, and taking an average of a 100kWh battery per car (it is less at the moment but some have more), at 100% efficiency it would take 1200 kW for 5 minutes (full charge) so the power station would have the capacity to charge 804 cars at the same time. Not a great figure if you consider the millions on the roads these days.
As a disclaimer though I must admit that although my principle qualifications are in electronics I am more to the communications than power and supply so am not well versed. Anyone seeing errors in my assumptions and calculations please let me know.
Mostly please ignore my nerdy ramblings