USB has been the standard for charging pretty much any small electronic gadget for years now but there is still some confusion about both what USB charging means in regards to compatibility and how you can charge USB equipment without a computer. Read on for a breakdown on USB charging.
The concept of USB charging
Many people ask for advice when it comes to USB charging becuase they’re unsure if a certain charger etc will work with their device. The answer can be both yes and no. We’ll come back to the “no” part later, but first off there are a few basic concepts that are important to understand about USB.
USB is basically the computer equivalent of an AC outlet, but standardized worldwide not just for certain countries. The standard USB power rating will be 5V 500mA which means that a device connected will receive 5V and be able to draw a maximum of 500mA (milliampere). To do a crude metaphor, think of the voltage as the type of power and the mA as the amount.
What this means is that you will never fry your device using a working USB port as USB is 5V and USB powered devices draw 5V. What you may run into is a lack of mA. External 2.5″ hard drives for instance tend to use 6-700mA which most computers will be able to provide, but not all. Also, some USB ports found on DVD players, car stereos etc are only 100-200mA. If your USB device requires more than what the USB port can provide mA wise, it won’t work but nothing bad will happen. It might also be that it will charge, but do so at a slower rate. At the same time, if the USB port provides more than what the device needs, it will work fine and nothing bad will happen.
The exception to this might be if someone has made chargers than use USB connectors but other voltages. I haven’t seen any such chargers, but considering how companies like HTC abuse the miniUSB port on their devices for things it’s not made for I wouldn’t be surprised. If you’re in doubt you can simply check the charger to see if it says 5V, but this is absolutely an exception (and theoretical one at that) not the rule.
The bottom line is that no working USB will damage your device. The worst thing that can happen is that it won’t charge it due to not providing enough mA or for another reason I’ll come back to, but that’s it.
Blocked USB charging
The “no” answer to the question above comes with something some manufacturers including Apple, Creative, Sony and others have started doing with their players: blocking USB charging. Basically this is a method of ensuring that you can only charge the device using a computer or a company charger. A USB cable has 4 pins, two for power and two for data. When connected to a computer, all 4 are in use. When connected to a standalone charger, only the power pins are in use. What some companies do is disable charging if there is no data activity so that you have to use a computer. If they provide their own official chargers that don’t use a computer, they often put in some small hardware trigger like having the two data pins connected inside the player which the player then recognizes and knows it’s an official charger.
This is a very bad thing to do for any manufacturer and just shows how greedy some of them has gotten. It totally defeats the purpose of having USB when you still need expensive official chargers to charge the device without a computer, but unfortunately a lot of companies do this. If you find yourself with a player that won’t charge off something like a USB AC charger that is able to provide enough mA, this is probably the reason, so be sure to check forums before buying a device if you want to use standard USb chargers.
As you might have gathered from the above explanations there are ways of charging USB devices without using a computer. The cheapest, most common method is to use a USB AC adapter which is basically a plug you plug into the wall socket with a USB port on it to plug your device into. As long as you have a player that doesn’t block this, it’s by far the cheapest way of getting power to your device. You can find these at your local electronics store, but I tend to order them from DealExtreme since they have Soshine chargers there which are both cheap and very good quality. They have both a US version, European version and a UK version and I can personally attest to these working well.
Another common USB charging accessory is the car equivalent of the USB AC charger. Just plug it into a car cigarette socket and it gives you a USB port to charge from. Again I got mine from DealExtreme, but while it’s not as common as the USB AC type of chargers you should be able to find one pretty easily more or less anywhere that sells electronics.
Lastly you have various battery packs that provide USB power. Basically these are packs that either have a rechargable battery, AA/AAA batteries or even solar panels that spit out USB power for your device. You can get these in any shape or form, from cheap emergency chargers to more expensive ones and not to mentioned heavy duty ones. Grahm reviewed the second one of these just last week. I’d highly recommend a durable, high quality recharger one and not one that run off AA/AAA batteries as the rechargeable ones are generally more reliable. Especially packs that use 4 batteries can be a bit shaky since the cheap ones don’t always have power regulators. This means that it feeds the 4×1,5V = 6V directly into the USB connector without downscaling to 5V. This doesn’t matter for most equipment out there, but there have been reports of such packs frying devices.
The bottom line is that USB charging is perhaps the most universal method of charging something ever as it can be done from any USB socket regardless of country or other “normal” limitations. With the exceptions of greedy companies blocking USB charging, you can be sure that any USB chargers you buy will work with your gear. I highly recommend getting some of the types of chargers mentioned here as they are cheap and very useful the day you find yourself without power and a computer.