[Coda]

If your battery is swollen you should really stop using it RIGHT AWAY. Swollen batteries are EXTREMELY DANGEROUS. They're an EXPLOSION HAZARD, and swelling only happens when the battery has been damaged in the first place.

Fully discharging a battery isn't bad for it -- in fact it's actually healthy for the battery to occasionally go through a complete drain-recharge cycle. Overcharging the battery is what's bad for it.

When you've got a swollen battery, it's from one of a few causes:

* The battery overheated. Don't leave batteries in a hot place, and ESPECIALLY don't charge them when they're hot.

* The battery has been physically damaged, perhaps by being dropped or stepped on. You can't necessarily see the damage from the outside. (There's no need to be paranoid and stop using a battery just because you dropped it, but if it swells, stop using it.)

* The battery has been electrically shorted, perhaps from water (which can include being operated in a humid environment or cold enough to form dew).

* The battery has been overcharged. Most modern devices are SUPPOSED to automatically disable the charger when full, but there are reasons this might not work or not be enough. You should avoid leaving a battery plugged in longer than necessary.

* The battery has been charged with dirty power. Don't buy cheap chargers. You'll break stuff. (Sometimes you can even see the problems in action from the touchscreen misbehaving while plugged in.)

Furthermore, due to the fire and explosion hazards, you should never dispose of lithium batteries in the trash. (It's actually illegal.) And if it's swollen, you shouldn't even use a battery recycling drop-off bin; you should take it inside some place like Best Buy and give it to someone in person for safe disposal.