Samsung Launches Galaxy S4 Inductive Charging Kit at $90

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livebriand

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"but has a limit of 500 mA which, while it is faster than a USB port of your computer, it has four times less power than the cable can get from a wall socket (nearly 2 A)." Not quite - most computer USB 2.0 ports are exactly 500mA. Phones tend to pull 1A from wall chargers, and tablets 2A. (USB 3.0 is 900mA, but I haven't seen any phones or tablets that support it. In fact, my phone only pulls 500mA when plugged into a computer even if 900mA is available, yet it pulls 1A from a charger.) (Earth to toms: PLEASE fix the issue with line breaks causing generic errors...)
 

Grandmastersexsay

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For $20, I would definitely buy it.

For $50, I might buy it.

For $90, Not a chance.

On Amazon, $72.28 can buy you a spare battery and the spare battery charger, all made by Samsung, not the cheap knock off stuff. It is just not worth it. I mean, how hard is it to plug a phone in? $90 is a rip off for something that should have came stock with the phone.
 

InvalidError

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" the alternating current in the charging pad, which then induces eddy currents in the other coil"

Wrong thing. Eddy currents develop from tiny voltages induced within a conductive material passing through a changing magnetic field. The small voltages within the material create conduction currents and associated I2R losses within the material so for most applications, they are considered parasitic - undesirable. Since larger chunks of conductive materials are more severely affected by eddy losses, efficient transformer call for magnetic cores with smaller metallic components to constrain eddy currents within smaller volumes of conductive material. That's why low-frequency transformers use laminated steel coated in non-conductive enamel/lacquer/resin instead of solid chunks and why high-frequency cores use powdered metal mixed with ceramics to constrain eddy currents within individual metal dust particles, thereby reducing I2R losses within materials.

Magnetic coupling is what enables transferring energy between two electrically isolated coils using magnetic fields, usually using a magnetic core material to guide magnetic flux along a predetermined path.
 

bustapr

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$5-$10 for a regular wired wall charger vs $90 for fancy wireless charger that has no real advantage. is there supposed to be some choice in this matter? I just dont see wy anyone would buy this knowing what it really is.
 

InvalidError

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Or don't want to have to worry about accidentally breaking it.

Personally, I would be perfectly happy with a $20 charging stand with pogo-style or equivalent connection - just as break-away safe but both cheaper and more efficient.
 

knowom

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Only the super rich would waste money on this as the price to convenience advantage is quite ridiculous you'd even be better off just buying a extra battery pack for the phone or two at that price.
 

bjaminnyc

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@$50 sure, $90 probably not. Investing in the convenience for a phone you're likely going to keep for 24 months isn't an entirely unattractive proposition.
 

sherlockwing

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Most phones ship with a 1A wall charger, the Samsung Galaxy S4 ships with a 2A wall charger so it in fact charges at 2A.

 

InvalidError

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While the charger may have a 2A rating, that only means you should not draw more than 2A from it.

You won't know exactly how much current is actually being drawn until you put a current probe on one of the power wires to find out exactly how much current is passing through it... could be more but will most likely be less than 2A.
 

Dinghole

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I'm a few days late here but I plugged my S4 into a kill-a-watt to see how many amps it drew when charging. It consistently pulled 0.1 amps from the wall.
 
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