That's not really the nature of Lithium-ion batteries. Most formulations have <5% self-discharge per month, which is very good for a rechargeable (standard NiMh cells can drop as much as 30% in a month). In most cases of what seems like self-discharge, it's a "smart" Li-ion battery losing a little power due to its voltage monitor. And there's nothing magical about batteries being connected -- an open circuit is an open circuit, doesn't matter where that open occurs (and yes, I am an Electrical Engineer... CMU class of '83). So if there's a noticeable drain, that's an indication that something's still powered. Could be the voltage monitor (my JTV-69 arrives tomorrow), I haven't seen the battery, but if there are more than two terminals, those others are usually for monitoring... this is one of the things that keeps Li-ions, which are kind of a tricky technology, from being overcharged or drained. Overcharging can lead to explosions. Draining below safe limits cause a parasitic effect, pretty quickly killing the battery for good. I used to do lots of work with batteries, in robotics. NiMh were more common than Li-ion... much less energy density, but relatively few problems. Same reason Li-ion only recently made it into hybrid cars.... issues.