Reviving old power tool batteries is something we all want, and need to do. These batteries are very expensive and tossing them away can be even more expensive.
There is a life span of these batteries, however we very seldom get to use them for that entire time. When charging and killing these batteries over and over again. It seems we have used them for their life span. When the actually truth is we have not. The more they get used, the better they perform. It is when we don’t use them that they become junk.
After sitting around on a shelf or in a drawer for long periods of time, they will form crystals around the battery. This process happens under the plastic protective coating. And since there are no screws to remove this shell, we don’t see the crystals. The crystals can melt back together providing the battery gets charged. But when you cannot charge the battery, there is no heat (energy) to melt these crystals.
When we plug a battery into the charger, the battery charger recognizes something is plugged in, but does not recognize that it is a chargeable battery. Therefore it does not turn on, it only throws a light meaning non chargeable.
The way the battery charger knows if it is a chargeable battery, is if there is a voltage, or amperage in the battery. So we must trick the battery charger by exciting the battery.
Look on the connections of the battery. There will be a positive and negative side to the post.
Connect any car battery charger to these post. Simply touch negative to negative, and positive to positive. Place the battery charger to no more than 20 amps and hold the connections for five to seven seconds.
You can do this same process with your car as if to jump start another car. Using jumper cables, connect positive to positive and negative to negative. Hold the connection for 3-5 seconds.
Once you have excited the battery. Place the battery back into its charging system and it will now take a charge.
If you do not get a charge light, repeat the steps. Try holding for 2 extra seconds. If at any time the battery becomes warm, or hot. Stop the process. You have over charged the battery.
So in short, most rechargeable batteries stop taking a charge because they have not been used enough. The battery has now crystallized a little and must be excited to start taking a charge again. This process was used years ago when coils would crystallize causing them not to send a spark to the spark plug. It was most common on motorcycles that would sit in the winter time. In the spring motorcycle riders would need to charge their batteries, and excite the coils. Some riders that didn’t know the process would replace their coils annually. Enjoy your power tools for many projects to come.