Cordless Power Tools

Charging a cordless tool battery seems like it would be an easy thing to do. Something that many of us have probably done time after time. Step one, remove the battery from the cordless tool as soon as you are done using it. Step two plug the battery into the charger that came with the cordless power tool. Step three let the battery sit on the charger until the next time you need to use the tool.

I know this does not seem like a helpful article thus far. I have just told everyone how to do what they already know. What you don’t know is this is not the best practice for charging your batteries. (Unless you are using the new Lithium Ion power tools) There are 2 things wrong with that step by step guide, can you spot them?

The standard battery for cordless tools (until recently) has been the Nickel Cadmium or NiCad battery. Cordless tool Ni Cad technology has been evolving since its inception, but it still suffers from a few side effects that can be easily negated if you know more about how the battery works.

NiCad battery side effect number one, memory. When you place a Nickel Cadmium tool battery on the charger before the battery has completely discharged, you are creating battery memory. What exactly does this mean. The battery just remembered the point at which it was discharged and thinks that this point is the point of full battery discharge. The battery will remember how much it had to charge from this point to get back to a full charge.

This will not happen over night. It will not happen the first time you place a half discharged cordless tool battery on the charger. If you are an avid weekend warrior or even if you only use your tools once a month. The odds are that you are used to placing your tool batteries back on the charger so that they have a full charge the next time you need them. This is your bane, the time and time again half charges will eventually lead to your batteries only holding a half charge at max charge.

So what should you do. That is actually an easy answer. Buy more batteries for your cordless tools. Always wait until your Ni-Cad battery fully discharges and then replace it with your spare and fully charged tool battery. You are ready to go, and you will never run into battery memory again.

NiCad battery side effect number two, overcharge damage. Simply put, if you keep your cordless power tool batteries on a standard charger until the next time you need it, you will shorten the total life of the battery. I say a standard charger because this is the normal single battery charger that comes with cordless tools. Most of the chargers that come with say cordless drill, are single cycle full power chargers. These chargers are meant for fast charging and removal when the tool battery is full. So what happens when you leave the battery on the cordless tool charger until the next time you need to use it. You will have been sending full charging power to the battery for too long and be over charging. You will notice that the battery will be very hot when you take it off the charger, this is bad and this will shorten the life of your battery.

What is the solution. Simple again, buy a two stage battery charger. Stage one, charge the battery at full power until it is full. Stage two, detect when the battery is full and adjust power to a trickle just enough to keep the battery at full charge for an extended time. With a dual stage battery charger, you can leave the battery on the charger for as long as you like with no damage. What’s more is you will not have a hot battery to put back into your cordless tool, that is good.

With a few simple changes or should I say with a few simple purchases, you can insure a long life for all of your NiCad cordless tool batteries.