Have you ever attempted to use a battery operated tool only to find the charge was only good for a few minutes, or it was totally dead? What if you only used this tool occasionally? Most batteries on the market today will last anywhere from 3 to 5 years if treated well.
Getting a dead battery right off the charger can happen to a battery that has not even been used all that much. Depending on the manufacturer, the charger can have a maintainer option that keeps the battery at its peak as long as it is plugged into the charger and your power is good. Except most chargers only charge the battery when you first connect it to the charger. If you have a charger like this, you need to “reset” your charger from time to time if you are not using the battery for extended periods. To reset a charger, simply unplug it and plug it back in. You should notice the charger going into the “charging” cycle after it has been reset. If this isn’t being done on a regular basis, the battery can actually be drained over time by some chargers. If left too long, this can put the battery’s voltage lower than what the charger would recognise as being a good battery. When most chargers run into a battery with an extremely low voltage, they won’t even attempt to charge the battery, and they might even have a “defective battery” light come on to tell you this battery won’t charge properly. This can be a little discouraging, especially if you have not even used this tool very much.
I have had batteries that had such a low charge that it would not be recognised by the charger. What I tried and it appeared to be successful, was to give the battery a little boost with another fully charged battery of the same voltage. This seemed to be enough for the battery to be recognised by the charger, and the charger would do the rest of the topping up. But what I noticed was the life of the battery was significantly shorter if it had been drained to this level.
This same principle applies to your cell phone battery, your laptop battery, or even your car battery. If a battery does not get cycled (used a little between charging), it can limit its useful life as well.
Again, if your charger has no indication of having a “maintainer” function, you probably need to unplug it and plug it back in again periodically. Also don’t forget to actually do something with the tool once in a while (you’ll get more done this way), and put it on the charger as soon as you are done. Pay attention to these minor details and your batteries could last a long, long time.