Originally Posted by jthiemann

Is that charging the battery directly, or a supply for the tablet?

Originally Posted by jthiemann

Then those numbers make sense, since the (nominal) battery voltage is 3.7V (I think) so the charging voltage just needs to supply something higher than that at a controlled/fixed current. (Including _usually_ a temperature sensor to prevent flaming battery situations :-) Actually, a temperature sensor is usually built into the LiIon/LiPol battery packs, that's what the third contact tends to be there for)

As such, the device can't be compared with the tablet power adapter, but rather, the charging circuitry inside the tablet itself. The tablet power supply can be 'dumb': supply voltage X at current Y. A LiPol battery charger needs to have some brains: Supply current A until voltage at battery reaches B, then switch to supply current C until voltage is D, then shut off (or supply trickle current E); unless temperature reaches F in which case kill the current. Or some variation of this.

I think the battery charger would make a very poor general-purpose power supply :-)