12-24v USB charger - Cyber Monday 2014

I always wonder why these manufacturers are so cheap in their cord length. 3 feet........really?
 
kgruber said:
I always wonder why these manufacturers are so cheap in their cord length. 3 feet........really?
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Because for most folks 3 ft is enough. USB extension cords aren't all that expensive and the price for the unit is really reasonable.

Jim
 
I'm trying to figure out how apple has manged to make it's electricity different than everyone else's. Why would a 5v 2amp charger "made for apple" charge and iPad any faster than a Samsung 5v 2amp charger? 5 volts at 2 amps is the same regardless of the brand and color of the charger.
 
weirdjim said:
What difference would it make? 5 volts is 5 volts.

Jim
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Voltage isn't an issue but some devices, I know iPads for sure won't charge unless the charger is putting enough amps out. USB spec is 500mA, the ipad chargers put out 2100mA.

There isn't any sensing going on it's just about having enough output.
 
weirdjim said:
What difference would it make? 5 volts is 5 volts.

Jim
Click to expand...

Apple devices detect USB Host charging (computer/laptop) VS Power Supply charging differently than Android devices. The specification calls for D+ and D- to be shorted for power supply USB chargers, and is usually what Android does...from what I understand.

Apple, on the other hand, has to be different. I'm not exactly sure how Apple USB chargers differ, but they do. If you plug in an iDevice into a non-apple USB charger, it will charge - just much slower.

http://www.maximintegrated.com/en/app-notes/index.mvp/id/4803
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As far as the cable, you want a 28/24 AWG cable, versus just a 28/28AWG cable. The 28/24 cable uses 28AWG for data, and 24 AWG for power. The 24 vs 28 gauge wire size means 60% more copper to move electrons around = less voltage drop. You don't want a voltage drop as that drastically hurts charging performance. The longer the cable, the more the voltage drop. Always use the shortest cable you can stand for best charging rates. I purposely use an extra long charging cable by my bed - slower charge = longer lasting battery. I sleep for 6-8 hours. On the go (car, plane, whatever) you'll probably want the fastest charge you can get.

http://lifehacker.com/cables-can-significantly-impact-the-charging-speed-of-y-1532784722

Of course, I get my USB cables from monoprice as they are great quality at great prices.

Again, I'm not affiliated with any of these websites.
 
cowman said:
Voltage isn't an issue but some devices, I know iPads for sure won't charge unless the charger is putting enough amps out. USB spec is 500mA, the ipad chargers put out 2100mA.

There isn't any sensing going on it's just about having enough output.
Click to expand...

True. If you plug in an iDevice into a 500ma port, it'll sometimes say it's not charging...but it really is. Just super slow. You could make a thanksgiving dinner in the time it would take to charge an iPad from empty. :)
 
cowman said:
There isn't any sensing going on it's just about having enough output.
Click to expand...

Unfortunately yes, there is sensing going on. The bastards at Apple made sure that you couldn't get optimal performance with anything other than a "made at apple" charger.

There ARE homebrew ways around it, but they are quite tricky.

Jim
 
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