Your explanation is right on target, especially the pressure/flow (like water in a pipe) being analogous to volts/amps. The eDGe "brick" is rated at 2.5 amps, and the Pocket eDGe adapter is rated at 1 amp. I have had no difficulties using the Pocket eDGe adapter to charge the regular eDGe device. The adapter does not overheat, and the charging time seems about the same, though I have never quantitated it. I dont know how much current (amps) the charging circuit of either device draws, but I suspect an adapter rated at 0.83 amps will be just fine. You should try it. AS long as its 12V, it should not in any way damage your eDGe. Let it charge a few hours and see if the adapter gets hot, and if the battery charges. I imagine it will be no problem, and it sure sounds convenient!