4.0 out of 5 stars Amperage claims a bit deceptive January 28, 2012
By K. Crawford
Amazon Verified Purchase
This product has two major issues:

1. While it's description claims it has a 2 Amp port and a 1 Amp port, the reality is that it has bridged the two ports and it can only source 2 Amps total. It is not capable of delivering 3 Amps combined like the description implicitly claims and could never simultaneously charge an iPad and a smart phone. (UPDATE: The technical details section now indicates more clearly the 2A total, which is appreciated.)

2. The 2 Amp port appears to be using the Apple protocol for USB power, so that port will only provide 0.5 Amps to most other devices.

The upside of this is the 1 Amp port somewhat over delivers, and can source 2 Amps if nothing else is connected and 1.5 Amps if the 2 Amp port is sourcing 0.5 Amps for a non-Apple device. Thus this product can support one-high power non-Apple device (in the 1 Amp port) and one lower power device (in the 2 Amp port).

Now some more background/details...

First, a little background on USB charging for those who don't know:

The USB power spec is for 0.5 Amps at 5 Volts... or 2.5 Watts. This was great up until the last couple years when devices have gotten really power hungry, particularly smartphones and tablets and to a lesser extent dedicated GPS's. Some of these devices use over 2 Amps, particularly the tablets like the iPad (or in my case the HP Touchpad).

Manufacturers of these devices therefore had a dilemma. If they had their devices pull more than 0.5 Amps, they risked damaging the power source, which could be a computer, that was only prepared to source 0.5 Amps. Thus the manufacturers have used tricks to determine whether their device is connected to an unknown source, at which point they purposely only draw 0.5 Amps, or to the dedicated charger that was provided with the device, where they can draw all the power they need.

There seem to be two common tricks used. The first is to short the two data-wires together in the charger. This is what most non-Apple devices do. Since a computer or older device wouldn't have done this, the device can assume it is safe to draw all the power it needs.

Apple seems to have taken a different approach, one that I don't fully understand but know can be seen by the fact that the data lines are neither open nor shorted when the charger is plugged in, and is more sophisticated and probably superior, because I suspect it allows the device to know exactly how much power it can use.

While Apple taking a better approach might be nice in concept, it's created chaos in the USB charger product category. What is the non-specific charger to do? They can't support both.

This device chose to go the Apple route for the 2 Amp port. I don't own any high-power Apple devices, so I can't say for sure, but I suspect this unit performs well with Apple devices. Using electronic equipment I was able to draw 2 Amps when putting a fixed load on this USB charging port. However, when I connect any of the 3 high-power devices I have (HP Touchpad (2 Amps), Motorola Triumph Android phone (0.85 Amps) and the LG Optimus Slider (0.7 Amps)), none of them drew all the current they could have, because they were expecting a shorted set of data-lines.

Luckily for my purposes, the 1 Amp port on this device uses the data-line shorting method. As such, it was able to deliver all the power my Triumph and Optimus wanted. However, for some reason, even when it was the only device connected, it would not fully charge the HP Touchpad at the 2 Amps it could have, because for one reason or another, the HP Touchpad rejected it as a high power charger.

To be honest, this surprised me because it was able to source the 2 Amps the Touchpad claims it needs and the HP Touchpad charger has the data-lines shorted. So I'm not sure why this didn't work.

Thus this device gets 3 stars (UDPATE: 4 stars) because it can source the current it claims (minus the somewhat deceptive 2A + 1A notation (UPDATE: Which is now more clear in the technical details)), would likely support an iPad like it claims, but falls short in other regards noted elsewhere.

For non-Apple users, or even more so mixed users (say an iPad and an Android phone?) this device is superior to the other device I purchased, the "Kensington K33497US PowerBolt Duo Car Charger" (http://www.amazon.com/gp/product/B003PU01M4/ref=oh_o02_s00_i00_details) because on that device, NEITHER port works with non-Apple devices (although it performed better power-wise, see my review over there for details).

I've ordered two additional devices:
- "Ultra Compact High Output Dual USB Car Charger - 2.1A Output" (http://www.amazon.com/gp/product/B00470C35E/ref=oh_o01_s00_i00_details)
- "Bracketron Universal Dual USB Car Adapter (UGC-298-BL)" (http://www.amazon.com/gp/product/B0056VNVV8/ref=oh_o00_s00_i00_details)

Hopefully one of the two of them will be able to deliver to their specs for my devices.

UPDATE: I've increased my review to 4 stars for two reasons:

1. The changed technical details text makes it more clear its total power capacity.
2. Of the 4 models I purchased, it's one of the two I kept and it's the only one I kept in unmodified form. That's got to count for something.

Jupiter and the Sun are the two largest objects in our Solar System, and as they orbit around one another, they create regions where their gravity roughly cancels out. These are the Lagrangian points, created whenever two objects orbit one another: places where gravity is such that another small object can follow along in the orbit without being pulled in or out. And since things aren't getting pulled out of there, they get stuck in there as well: and so we have two large clumps of asteroids (and miscellaneous smaller space debris) in Jupiter's orbit. These are called the Trojan Asteroids; the group ahead of Jupiter is known as the Greek Camp, and the group behind it the Trojan Camp, with the asteroids in each camp being named after famous people in that war. Together, these two camps have as many asteroids as the Asteroid Belt.

Other stable patterns are possible, too: another one is what's called a 3:2 resonance pattern, asteroids whose motion gets confined to a basically triangular shape by the combined pull of Jupiter and the Sun. This group (for Jupiter) is called the Hilda Family, and their route forms a triangle with its three points at the two Lagrange points and at the point on Jupiter's orbit directly opposite it from the Sun.

None of these orbits are perfectly stable, because each of these asteroids is subject to pulling from everything in the Solar System; as a result, an asteroid can shift from the Lagrange points to the Hilda family, and from the Hilda family to the Asteroid Belt (not shown), especially if it runs into something and changes its course.

The reason that Pluto was demoted from planet to dwarf planet is that we realized that these things are not only numerous, but some of them are quite big. Some things we formerly called asteroids are actually bigger than Pluto, so the naming started to seem a little silly. So our Solar System has, in decreasing order of size, four gas giant planets (Jupiter, Saturn, Neptune and Uranus); four rocky planets (Earth, Venus, Mars, and Mercury); five officially recognized dwarf planets (Eris, Pluto, Haumea, Makemake, and Ceres); and a tremendous number of asteroids. (We suspect that there are actually about 100 dwarf planets, but the job of classifying what's an asteroid and what's actually a planet is still in progress -- see the "dwarf planet" link below if you want to know the details)

Ceres orbits in the Asteroid Belt, about halfway between Mars and Jupiter, just inside the triangle of the Hilda Family; Pluto and Haumea are both in the distant Kuiper Belt, outside the orbit of Neptune but shepherded by its orbit in much the same way that the Hildas are shepherded by Jupiter; Makemake is what's called a "cubewano," living in the Kuiper Belt but unshepherded, orbiting independently; and Eris is part of the Scattered Disc, the even more distant objects whose orbits don't sit nicely in the plane of the Solar System at all, having been kicked out of that plane by (we believe) scattering off large bodies like Jupiter.

But mostly, I wanted to share this to show you how things orbit. This picture comes from the amazing archive at http://sajri.astronomy.cz/asteroidgroups/groups.htm, which has many other such pictures, and comes to me via +Max Rubenacker.

Taken inside a CAVE


At a restaurant

Other indoor shots with good lighting

FOOD



Museum exhibit