Explain charging process change, please

The older iPods can charger on either/or USB 5V or FW 12V. The new IPT G2 and Nano G4 can only charge with the USB 5V option.

The explaination is simple:

Over two years ago Apple switched to USB charging for iPods. They maintained compatibility with Firewire to give other manufacturers a chance to make the change. Unfortunately, the other manufacturers, for the most part, just 'sat on their hands' and didn't make the change in their accessories.

Firewire charging and USB charging use different pins in the docking connection. Firewire voltage can vary from 8 to 30 volts while USB is just 5 volts.

Apple has never explained the reason for the change. We aren't supposed to speculate on Apple's plans.

Let me just say, as one who has been involved in the design and construction of electronics equipment for years, if I were trying to make a small device with lots of features, I wouldn't maintain two sets of charging circuitry and would drop the higher voltage charging for size and heat reasons. Apple may well have a completely different reason for making the change.

BTW, according to http://pinouts.ru/Devices/ipod_pinout.shtml , pins 19,20 are the Firewire + charging pins and pin 23 is the USB + charging pin.

F Shippey wrote:
Let me just say, as one who has been involved in the design and construction of electronics equipment for years, if I were trying to make a small device with lots of features, I wouldn't maintain two sets of charging circuitry and would drop the higher voltage charging for size and heat reasons. Apple may well have a completely different reason for making the change.

We shouldn't speculate, but since we are 😉, let me say that Apple may have chosen USB over FW because all those Windows machines out there don't usually have FW, but they have USB. No more excuses for PC owners not to own an iPod.

You get "Charging is not supported with this accessory" if you plug an iPod nano 4th generation, iPod touch 2nd generation, or iPhone 3G into older accessories including Bose SoundDock I, other older speaker docks, and and some built-in iPod car adapters.

To charge your new iPod with older accessories, you need an adapter from Scosche (among others):
http://scosche.com/products/productID/1667
http://scosche.com/products/productID/1695
http://scosche.com/products/productID/1694

The reason for the charging issue? The new iPods only charge from "USB power" while the older accessories only provide "Firewire power". "USB power" is 5 Volts on pin 23 of the 30 pin iPod connector and "Firewire power" is 12 Volts on pins 19 and 20.

Hi there - just wanted to ask a question re this 5v 12v. My daughter was running an itouch 2nd generation of a JBL Stage II for the last two months. I had no idea about this 5v 12v change so poor thing plays the iTouch it runs out has to charge it then can play it again some hours later - I know it cant charge due to the 5v/12v.

BUT today the iTouch wont play out through the docking station - I tested an iNano - an Itouch generation 1 plus an iPhone generation 2 /3g all played through the speakers (JBL) no probs - Is it possible that running the iTouch 2nd gen on this has broken the iTouch inside? you gusy seems to be well up to speed on the technical side - is it possible you can do damage to the iTocuh running it on a docking station that cant support charging? many thanks guys