Small charger, big output?
 

Folks, I've read the ultimate charger solutions thread with interest. I think I'm looking for something a bit different.

The 'stock' Samsung/Blackberry chargers are cubes of about one inch with a single USB outlet. I love the small form factor and ease of packing, I don't love the relatively paltry output (often around 750 mAh.)

I know an iPad type charger would work, and it puts out 2.1A, but it's almost twice the size. Has anyone stumbled across a similar beast with a slightly smaller form-factor? I don't have multiple devices to charge (single USB is fine), but I do want to charge it more quickly.

I'm not interested in an investment here. Worst case scenario I stick with my own existing solution, but if you've come across a miniaturized USB charger with good output for $10 or so, I'd love to know about it.

I think the size is a function of the output: more output requires bigger size.

Apple's iPhone charger is small and puts out 1A.

I wonder if there are ratings of efficiency on these things? The limiting factor seems to be heat generation and heat dissipation.

Another consideration for the OP is to make sure to get a well designed power supply. You want a high quality switched-model power supply with good electrical isolation from the mains and ideally with current limiting. Does that come with being UL listed?

Just thought these factors should be considered in addition to raw power and form factor / size.

The ipad charger is about as good as they come. It has high quality components (typically costing twice what the cheaper chargers use) and is efficient, so the unit is small.

Form factor or volume is proportional to power/efficiency and is mainly driven by heat dissipation.

High quality components tend to give a high efficiency and usually incorporate better protection circuits.

The stock Samsung Galaxy S4 charger does 2.1 amps and is fairly small... maybe 80% the size of an iPad charger. I also have a smaller Samsung charger (the 1" cube size the OP mentioned) from a Rugby Pro that does 1.5a.

I've recently switched to this PowerGen 3.4a dual-USB charger for travel. The 2a side charges my Asus T100 Windows 8.1 Tablet/Hybrid just fine and the other (with ~1.4a remaining depending on the load of the tablet at the time) charges my Galaxy S4 enough in most situations, plus I can always get a full 2a to the S4 if necessary by switching ports.

The Amazon Kindle PowerFast charger (link) outputs at 1.8A, and it is tiny. It charges my phones just fine, and it will charge my HP TouchPad somewhat quickly.

I was fortunate to pick two up for $2 each when they had a sale in September. If it drops back down to $10 (which CamelCamelCamel lists as the lowest price ever), I'd recommend it.

From my experience, the size of the charger has little to do with the output. When I got my Samsung Galaxy S4, I found that many of the chargers I have didn't charge it fully (or at all), so I did a round-up of all my USB chargers to see which ones worked and which didn't.

Two of my smallest chargers (ones with foldable AC prongs) put out nearly 2A, which is enough to charge the S4 efficiently. One of these was the one that came with my Edimax BR-6258n travel router. That one might not be available separately, but this experience tells me that it's at least possible to get a matchbook-sized charger with 2A output.

Nice catch - I just bought a stock S4 charger on E-Bay for a grand total of $1.75 including shipping. At that price, I thought it was worth taking a gamble on. :)

At $1.75 from eBay it'll be as genuine as any good BallStar shoe.

Samsung charges $39.99 for the white 2A charger that came with my S4. I'd be skeptical of anybody selling the genuine OEM charger for less than $20 or so. Many "genuine" products are actually fakes that don't perform as well as the OEM product, so adjust your expectations accordingly. You might get lucky!