The Anker 24W charger differentiates itself from most of the USB car chargers out there in a few ways, but at first glance, it isn't very noteworthy.
This little 2-inch-long white dongle plugs into your car's 12V power outlet and provides 5V USB power for your gadgets that need it. I wasn't a fan of the white and gray, "iDevice-esque" color scheme and would have preferred a darker finish to better blend with most cars' dark interiors. The unit also uses a sealed design and can't be opened to swap fuses -- presumably, this is to streamline the compact device's design and because most people couldn't be bothered to swap fuses on a car charger when they could just buy a new one.
However, I liked that the device didn't have an LED power indicator light to draw unnecessary attention to itself at night.
Double the ports, double the power
Things get interesting when you start to pay attention to the business end, where the USB ports reside. Firstly, this is a dual-port charger that is capable of charging two USB devices at once. Furthermore, the ports are high-speed USB chargers that can output up to 2.4 amperes of current to charge compatible tablets and to fast-charge smartphones that can handle the additional current.
What's more, those ports can output their maximum 2.4 amps of current simultaneously for a claimed total of 4.8 amps. Most dual-port chargers that I've tested can only output maximum current through one port. Now, with this, if you're in a cross-platform household and wanted to charge an iPad and a Nexus 10 at the same time, you could.
The best of both worlds
However, the two USB charging ports are not identical.
One is labeled Apple and features the unique pin configuration and circuitry required for Apple products, such as the iPad, to charge at their maximum rate of between 2.1 and 2.4 amps, depending on the generation.
The other port, labeled Android, is designed to charge non-Apple devices at their maximum rate -- anywhere between 0.5A and 2.4A, depending on the device. Interestingly, despite being labeled "Android" this port is equally adept at charging Windows Phone, BlackBerry, and other USB-powered devices (such as GoPro cameras or GPS devices). I suppose labeling the ports "Apple" and "Not Apple" would have just been too awkward for Anker.
Anker specifically states that the 24W charger is not compatible with Samsung Galaxy Tab devices. A bit of research reveals a well-known quirk of Galaxy Tab devices' hardware and software that prevents the tablets from charging with non-Samsung chargers.
As a cross-platform tester, who often juggles an iPhone and an Android phone for work, and as an Android user who's surrounded by a circle of iPhone-toting friends, I found the Anker 24W charger's ability to offer charging for both worlds to be extremely useful.
If you're not a cross-platform user, you can also charge two Android or Apple devices at the same time using the Anker 24W charger, but there is a potential catch. A device that finds itself plugged into the "incompatible" outlet may choose to recognize the charger as a computer's USB port, not a fast-charger, and revert to the slowest 0.5A rate of charging.
This is sort of the 24W charger's Achilles' heel: by choosing to appeal to both Apple and Android users with one device rather than two separate products, it's possible that it's not really perfect for devoted users of either platform. If you want to charge two iPhones at the same time, you've got some decisions to make about which device will get the fast-charging and which will have to trickle-charge. I suppose you could swap back and forth. If you're charging an iPad and an iPhone, you don't really have a choice but to trickle-charge the phone, as the iPad won't charge from the other port.
Android users have it a bit easier, as many Android devices will actually still charge reasonably quickly when used with the Apple-specific port.
However, if you're only carrying around one device, having the extra powered USB charging port around for a friend or family member to use in a pinch is nice, whether it is or isn't the optimal charging rate for the other device. Any port in a storm, so the saying goes.
Pricing and availability
The MSRP for Anker's 24W car charger is $35.99, which is about double or triple what I think most users are comfortable spending on a third-party car charger that doesn't include a Micro-USB or Lightning cable. However, I was able to find the charger offered for just $11.99 on Amazon at the time of this review. That's a much more reasonable, even generous price, even if you only plan on taking advantage of one of the Anker's two fast-charging ports. Look for a deal like this and you won't be disappointed.