The Galaxy Tab line from Samsung does what other manufacturers (e.g. Apple) do and add a level of proprietariness to chargers by requiring a the data pins to be connected by resistors of a certain type. This means that while the connector is physically USB and the charger uses the same voltage and amperage as other USB charging gear, none of the Tabs will charge off gear that hasn’t been specifically tailored to Samsung. This means that even if you have several devices that can charge off the same charger in theory, you’re forced to carry around more chargers just for the heck of it. Another major issue is that while Apple sells enough units with their version of the system to make most accessory manufacturers add support for its products, the same can’t be said for Samsung.
The solution comes in form of an accessory – or rather a type of accessory – that simply adds that “charge activation hardware” to your existing USB cable. There are many such adapters out there, but the one I bought was a $2.70 OEM adapter for the P1000, which you simply plug between your Samsung USB cable and the charger. While it’s intended for the P1000 (original Galaxy Tab), it also works on the newer models. It adds about 15 cm to your cable and “magically” makes your Tab charge off otherwise unsupported chargers. Now my 7.0 Plus is happy to charge off my iPad’s charger, which saves me from having to bring both.