I remember a few years ago one of the sales people at my local hardware store told me they were expecting the arrival of new battery powered circular saw, I think it was a Makita. On hearing the phrase battery powered circular saw, I laughed out loud and told him to call me when the battery powered table saws arrive. Within a couple of years I had purchased one of those battery powered circular saws that I so willingly scoffed at just a couple of years earlier. I soon discovered that having portable tools had huge benefits. Thats why companies like Porter-Cable, Makita, Delta and others have focused on these areas.

These days battery powered tools are available is drills, drivers, impact drivers, routers, jig saws, portable planers, circular saws, reciprocating saws and chop saws, and even Ryobi has battery powered chain saw that works well for big jobs that other tools cant handle. So to see how to get the most from these tools.

Lets stop for a moment and look at batteries that power these units. Most power packs that drive these tools are a series of small rechargeable batteries all wired together to give the optimum power. These rechargeable batteries are very similar to the flashlight batteries that you buy for your TV clicker and garage door opener and various other home products.

The difference between rechargeable batteries like Duracel and Eveready, are that the rechargeables have higher quality shells and consist of slightly different components to make them safe to recharge. The rechargeable batteries that are wired together are normally nickle cadmium (nicad) 1.2 volt batteries. When they are wired together in series ... 8 together equals 9.6 volt, 10 together equals 12.2 volt, 12 together equals 14.4 and so on. That is how more power is generated, more little batteries, more power, and of course, more weight.

The more batteries that are wired together, the greater the torque (or twisting power) of the tool. Torque is created by a combination of horse power and speed, and high speed does not necessarily mean high power. Conversely high power does not necessarily come with high speed..

You will find another type of battery on the market called a nickle-metal-hydride (Ni-MH). These batteries use compounds that give the batteries a slightly longer life (they also cost a bit more to purchase). Some contractors prefer tools that will give them longer battery life which is the reason for this more advanced rechargeable battery version.

As woodworkers, we all know one thing, HEAT is our greatest enemy. When saw blades get too hot they lose their tensility and become dull, screws that are driven into hardwoods can snap because of the high heat created by friction, and heat can burn out the electric motors of our machinery if we are not careful. Heat is also the enemy of batteries. All batteries heat up when they are being recharged. The larger battery packs such as 18 volts and larger tend to heat up even more because there are so many batteries in the packs and they dont have heat dispersion characteristics as smaller packs because there are so many batteries next to one another. Batteries tend not to take a charge when they are hot, so keeping the ambient temperature normal to cool is a benefit.

On the flip side, batteries do not do well in cold either. Once the temperature drops below 14 degrees Fahrenheit ( minus 10 Celsius) batteries do not perform well (if at all). Most batteries will lose their power when the temperature gets this low.

The recharging of batteries is a bit of a mystery to a many people. The tendency is to keep batteries fully charged all the time. In truth, batteries need to be exercised in order to keep them in top shape. This means they should be fully discharged every few months, then fully re-charged. Topping up battery charges will make the batteries lose their effectiveness, and after a time they will only take a partial charge because that is what they have become accustomed to. This means they will lose their ability to use the full charge. If your older cordless device is doing this, sometimes you can rejuvenate the battery by charging and FULLY discharging it several time.

My old 9.6 Craftsman portable drill, which is now 10 years old has been one of the best tools I have ever owned. I have no idea how many screws it has driven, holes it has bored or blades it has ground, but its batteries have almost given up now. I checked on the price of new batteries and it will be more cost effective for me to upgrade to a whole new unit ... but I have no intention of getting a big hulking unit, with tons of power, I dont need it and I refuse to pack around all that battery weight, so I am currently investigating some 12 volt units and looking forward to another 10 years of service from my new drill, and when I need more power, I always have my trusty plug-in drill, and the hassle of extension cords that goes with it.