If you're going to purchase a cordless tool, then you should really think about getting one with Lithium ion batteries. They cost more, and it's easy to think you could just buy a cheaper model and get a spare battery, but it's not the same. Lithium ion batteries are a true hassle free solution.
Weight - this is an important factor which you must keep in mind. You will find that some drills are lighter than the rest and hence you can hold onto these for a longer period of time and you will also be able to operate it for a longer amount of time. If you wan tot work on an installation project then these ones are the best for you. Weight is something which you really need to pay attention to. If you see that it weighs a few oz you will think that it isn't a big deal but then after you hold onto it for a long time then you will start to feel the difference.
Why is this important? If you have a relatively new PC the only problem you will get are error messages relating to the clock on start up. No big deal. If your PC is older then a low battery could be a nightmare. I had a PC which once lithium battery stocks every few months refused to boot. Rather than take the PC in for repair or start replacing parts myself the first thing I did was look at the BIOS settings. It was soon obvious that the BIOS settings were corrupt (wrong bus speed). I put a volt meter on the battery and sure enough it was reading 2.2 volts.
Batteries - Many of the battery products found at the dollar stores are made with carbon zinc, as opposed to lithium, so they do not last as long. Carbon zinc can also leak, thus doing damage to your electronics.
External power supply delivers power the motors. Power supply to micro controller circuit board should be Lithium battery stocks separate and powered by computer universal serial bus USB Universal Serial Bus connection. Both power supplies ground connections must be in common to each other, for the servo motors to function properly.
My.Vu offers the Crystal which is an elegant Lithium mines Ontario hand-free viewing eyeware device with earbuds and VGA resolution and a USB rechargeable battery with up to hours viewing time.
If your drill didn't come with a second battery (my cordless Bosch drill did) than you will either have to purchase a second battery or take a short break until your battery is ready.
Recharge the battery to full again and repeat the above steps a few more times. This will allow you to use the battery for a longer time and you can do this no more than once a month. Replacement batteries can be expensive and stretching out their use when you are on a budget can help.