The only up-side to the current one is that its lifespan roughly matches one day at work, so it's pretty convenient for the battery running out at the end of the day (if it's a day I'm getting out early, I turn the light on to wear out the battery faster) so it's a clean recharge. It struck me just now that it'd be really handy if things with built-in rechargeable batteries had a Discharge function, that drained the battery to zero for you, upon activation (since recharging a dead rechargeable is better for the battery than charging one that still has some life in it).
It reminds me of when I'd use rechargeable AA batteries in my Walkman and Diskman. When they'd died enough so I couldn't get any more standard playback from them, I'd take the tape out, trick the Walkman/Diskman into thinking there was a tape in there, then have it fast forward until the batteries wore out enough to not support that. Then, I'd plug them into this little dancing skeleton I have to eke the last bits of juice out, before popping them into the recharger.