What other cordless tools would you like to have?

Take a look at what voltages those are available in. Some power tool will only be available in 12 or 14.4 versions. Others will require Li-Ion to get the full line of tools available. With so many cool tools to choose from, plan carefully for future purchases before you commit to a battery voltage and technology.

How much power do you really need?

Higher voltage will give more power. But how much power is really necessary? If you're only drilling some pilot holes or driving screws into drywall, then power makes no difference. If you want to drill into concrete, you'll need more power. More voltage isn't always needed.

Do you already have other cordless tools?

If you already have some cordless tools, getting something that matches up will be useful. By doing that, you'll end up with more batteries for each of those tools. That can be a big point and certainly something to consider. You may also think about what other people you know have, in case you borrow a tool or loan one to them. Also you know where to find the right battery for your power tool in case you run out of one.

How often will you be using this tool?

If you're using the tool not too much, the weight may not matter much. Larger voltages are achieved by using more cells, so the batteries get much heavier as the voltage goes up. The exception is that Nickel Metal Hydride batteries are slightly lighter than Nickel Cadmium, and Lithium Ion is lighter yet. There is also the Amp Hour rating to look at. More Amp Hours means the battery will be heavier as well.

How long will you be using this tool at one time?

Are you going to be doing jobs over your head? If so, light weight is going to be important. Material will be important as well. Drilling through pine and drywall doesn't take much. Oak and concrete takes a whole lot more. Carefully considering all of the jobs you'll be doing will help decide what exactly you'll be needing.

How much do you want to spend on this tool?

Lower voltages are still incredibly useful, yet the cost will be significantly lower. If you want to save on cost, 12 V or 14.4 V may be your best option. 9.6 V may even be the best option in some cases. Just remember that buying too little could mean problems down the road with too little power. Buying too much may be too heavy and make the tool less usable in that way. Pay attention to the tool weight, battery weight and torque, then balance them so you can get what's important to you in a tool. Keep in mind that bigger isn't always better, so buying for the biggest numbers is pretty silly.

source:
toolbarn.com