Charge Your Phone in 30 Seconds? An Israeli Firm Says It Can
blogs.wsj.com
blogs.wsj.com
Consider internal resistance, power measured in watt-hours, and thermal behavior. When I was a kid, I grew around drag racing. Lots of times, I saw incredibly powerful cars try to put over 1000hp to the wheels at once, and just snap an axle or explode a transmission.
An iPhone battery is about 5.45 watt-hours. To charge that in 30 seconds from mostly dead (say 5 watt-hours), you need over 500 watts, discounting any thermal losses! Do you think the tiny solder joints at the power coupling are really designed to take 500 watts of power? Devices designed for 500 watts of power look more like your refrigerator.
That is to ask, is it theoretically possible with high end materials to actually pull it off, or is there a physical size limit to using that power?
amps = volts / ohms watts = volts * amps watt-hours = watts * time
Bigger wire = less resistance, generally. So to increase amperage (and thus power), you need bigger wire. But resistance turns power into heat, so if you're trying to shove more power through, waste heat rises. Eventually, it can melt the solder joints that hold circuits together (solder is a very soft lead alloy with a low melting point). Meanwhile, too much power can easily fry the silicon of actual computer chips, and excess heat can cause other problems.
But rather than go down that road - an analogy that helps me understand amps is to think of it as bandwidth of water flowing through pipes. If you try to force too much water through the pipes too fast, they explode from pressure.
It's a pretty straight forward formula. To lower the resistance, you either decrease the numerator (but a zero length wire is pretty useless) or increase the denominator (a huge-ass not even necessarily infinite, but just a conductor the cross-sectional area of say, the Pentagon, is technically possible but utterly pointless unless you're transmitting electricity cross-continent or whatever.
However, the resistivity of a conductor is its inherent property and so if there were a way to get a material whose resistivity was zero. Then you could transmit huge-ass amounts of energy over hair-strand thin wires because since <rho> is zero, you can play with other parameters in that formula without any fear. Hmm... (hint hint)
the search continues...
This means for a given contact resistance, the energy dissipated as heat into that contact is proportional to the square of current. Note, however, that you can increase the power also by increasing voltage, and not needing lower resistance contacts. That is why laptop chargers are usually 19V, and power transmission lines are 500-750kV.
https://www.google.com/search?q=toaster+wattage&client=ubunt...
Of course, the rate of change of temperature might be a little shocking - you can imagine that the battery case might heat up 20-30 degrees in the 30 seconds of charging. (~1 degree Celsius per second)
Most of the pins of a CPU are actually power pins, because it can use >100W @~1V => 100 Amps through a lot of very small pins.
Too simplistic of a model.
That's not the charger, that's the battery attached to the phone. A Li-Ion would blow to pieces charging at 120C (120 times the capacity).
So what's wrong:
- that's the battery
- they don't actually say the battery capacity (the phone would report 100% charge even with a 100mAh battery, if it's "fully charged").
- they don't say anything else about the battery (weight, internal resistance)
- the current provided by that plug they connect to the battery can probably be used to weld thin metal, if the battery capacity is close to the original one (think sparks/small fires in an accidental short circuit)
That thing is fed with standards copper-wires that can handle current, that can be of a certain voltage and amperage -- both are presumably linked. You can do funky things with time, like alternating, but… other than shove with higher voltage, I don’t see how you can feed that much energy in there, not unless you change the battery technology. And that’s not possible.
Therefore, what they have and the big bulky thing is a prototype battery. IT is an order of magnitude too big for the moment — not really a problem until you go though industrial design, I’m guessing. One that appears not to heat as much, otherwise that think would be burning when holding.
My question is: why do we have to guess so much from a video?
This would destroy batteries - wouldn't suggest this at all unless you only want your battery to last a year.
Edit: Some resource - http://batteryuniversity.com/learn/article/ultra_fast_charge...
Are there any applications for this for helping with stuff like buffering power generated by solar and wind? Anyone?
This should have implications for car batteries as well. Tesla is essentially a car running on very many laptop batteries.
Thus if you can charge a phone in 30 seconds. You can probably charge a car with distributed battery modules in similar speedy time frame.
This will mean pollution free cities in the long run, clean cars powered by Thorium reactors. Imagine mega cities without the car pollution.
Shorter time frame, your laptop should be able to fully recharge 50 watt hours in 300 seconds with this type of battery.