Sax Maniac's Journal: All USB chargers are not alike

So I have a bunch of chargeable USB devices around the house, phones, PDAs, GPS receivers, and the like. The good ones these days all charge off of USB, instead of relying on a bevy of proprietary connectors. Most of the time they come with a wallwart that I more or less ignore. After all, it's USB. Why unwrap an extra wart, only to lose it? Surely USB is a standard and they are all compatible, right?

I got the first taste of this when trying to plug my wife's KRAZR into a USB charger, the device complained "Unauthorized Charger". Say what? Obviously this is a corrupt vendor's decision to make proprietary connectors, not for technical reasons, but to gouge more cash out of customers. We ponied up for the car charger. Now the nuvi (GPS) doesn't like it, as it thinks a computer is connected and switches into data mode. Bad USB citizen. We're stuck with two chargers for the wife's car.

I finally looked at the wallbricks, and lo and behold, they *are* different. Turns out the USB spec allows a device to draw 100ma when first plugged in, and up to a maximum 500ma if it asks nicely and the computer allows it.

A wallbrick has no such restrictions. Taking a quick look, I have three different wallwarts, one for 500ma (an old Palm), 750ma (the KRAZR), and 1A (G1 phone).

Try charging a device that wants 1A at 500ma, and it takes a long time! On the flip side... well, I'm no EE, but I imagine you could cook your devices to a nice toasty black, should you plug a 500ma device into the 1A adapter.

Back to a pile of wallbricks. Is it the future yet?