Power Tool Battery Chargers

A lot of power tools are powered by rechargeable batteries these days. Each tool comes with a charger to recharge the batteries. Most people just leave the battery (or spare battery) in the charger all the time so that its ready when you want to use it.

As you accumulate more and more tools you end up with more and more chargers plugged in 24/7 -- here is a picture of the end of my bench with 5 chargers:

I have all the chargers plugged into one power strip so that I can switch the strip off and not have the phantom load of 5 chargers on all the time, but I'm not very good about unplugging the power strip, and it will go for weeks at a time with all the chargers plugged in.

I decided to see how much power the chargers used after they fully charged the batteries, and are just sitting there waiting for something to do. The answer was a surprising 18 watts! This amounts to 160 KWH a year and 300 lbs of CO2 emissions -- not to mention $20 a year of extra electric bill charges. What a waste.

Most of the chargers use 3 watts when idle, but the Panasonic drill charger used a whopping 5 watts sitting there doing nothing.

I'm going to get one of the wind up timer switches and plug the power strip into this. This way, when I want to charge the batteries, I just rotate to the switch to 45 minutes or a hour, and it will charge the battery up, and then turn off after the hour is up. Another approach would be to use one of the timers that runs things for a time period each day that you can set -- this way the chargers could run for an hour a day, and be off the rest of the time -- plenty to keep the batteries charged.

KillAWatt showing 18 watts for the
5 chargers at idle.

Gary December 14, 2008