When fired point blank, plastic BBs can hurt as much as rubber bullets, however most people engaging in military simulations with airsoft guns wear thick military garb. Additionally, precautions are taken to protect the neck, face, and eyes. Many people chose to wear a balaclava around their face and neck and edison battery ANSI approved eye protect is a must. The only place that plastic BBs can really cause damage is to your eyes.
Deterioration is a function of temperature and charge level. Don't make the mistake of storing the battery fully charged, as that is the state where it breaks the fastest due to heat. Charge it to take it out and put it like that on the back seat of your car avoid direct sunlight and preferably put the mini lithium facts notebook on a firm flat surface while operating it.
ONickel Metal Hydride (NiMh) - Popular battery about 1-2 years ago. They are lighter than Nickel Cadmium batteries, but heavier than Lithium batteries. These should be cycled once in a while for optimum performance.
On the second point, iPOD batteries are smart charging. Now, you can't use your iPOD Nano battery to help study for a test! Rather, they're smart because they can tell the charger when they're almost full. When your iPOD is charging, it charges up to 80% capacity in no time flat. Then the iPOD battery tells the charger to slow down so the charging process goes lithium bettery stock from warp speed to snail's pace. This ensures that the battery doesn't overcharge, and makes certain that you're spending your time with your music, and not spending your cash on iPOD batteries.
You have more power to perform work better and faster such as drilling and screwing than the smaller model. Once I used the 18v model I found that I prefer to use it more often because it gives me more power to complete the same task with less effort. At the end of the day it is better and faster, productivity counts.
So, in summary, if you have a PC which is showing clock errors or BIOS problems look first at the little 3 volt battery. It could save you a fortune. Happy computing!