What would you do without them? Seriously, if every single battery of every single type were suddenly zapped out of every single thing that it operated, what would any of us do?
If you have your PC case off you will see something on the motherboard that looks like a small thick silver coin. That is the battery. There are other types of battery used on newer machines (Ni-Cad, NVRAM) but these much less frequently found and so I won't discuss them further.
4) Size: terms like slim, ultra slim, main, and extended are commonly used by different vendors and is normally determined by the battery type and capacity. You can offset this by selecting a battery made from lithium ion stocks ion or lithium polymer since they pack more power in the same amount of space.
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.
For the most part, laptops do not come with batteries with extended life periods. For example, the typical laptop Lithium battery stocks will only last around an hour or so, which leaves you little to no time for work or communication while on the go, unless you happen to be nearby a place for charging. Then it kind of defeats the purpose of a laptop for most people anyways. The laptop is supposed to be mobile. In order to make your laptop fit your lifestyle best, you will need to make sure you look for high quality laptop batteries.
The battery will re-charge a little if placed on a hot surface, like a radiator. Never place a mobile phone battery on a hot surface! There is a significant chance of explosion with extreme heat. A modern Lithium mines Ontario battery becomes less efficient the warmer it gets.
That's why manufacturers have created external laptop batteries that can be attached to the laptop with the help of an AC adapter. These external batteries can run for 5-7 hours with on a single charge. The battery life depends on the type of battery; lithium or Nickel, and the brand.
Grooming items are iffy but worth checking out. Shampoo is a decent find as are scrubbies/loofahs. Items like Chapstick and Vaseline can often be found there and my very favorite soap (Yardley oatmeal and almond) is almost always available at the dollar store. Nail files, packages of combs, tooth flossing sticks are of value. Skip the cotton swabs (too flimsy and could be dangerous), make-up (due to lack of regulation), and make-up remover pads (can I just say UGH!?).