Power Tool Batteries

Bosch BatteryManufacturers and technology have come a long way in the development of cordless tool batteries.  What was once a dream to have a power tool without a cord has become a reality.  Not only for a drill but high demand power tools.  Tools that were once thought would always be married to a power cord are now becoming cordless. Over the years manufacturers have primarily use three types of batteries.  First, there was NiCad and NiMH, the were the two primarily types of batteries.  Over the years, these types of batteries have been dropped for a more favorable Lithium-Ion battery.

Types of Batteries

Nickel Cadmium (NiCad) – This was the battery that started it all.  NiCad is the oldest and most reliable battery.  NiCad stands the test of time.  They have a high recharge cycle life, meaning they can be recharged over and over, longer than the NiMH.  They are not as temperature sensitive as the NiMH, which means you can use them in cold or hot weather.  NiCad is cheaper than NiMH.   NiCad batteries tend to be more harmful to the environment when disposed of, that's why you see companies such as Dewalt sell NiCad in the states and NiMH in some European countries.  Some European governments put heavy taxes on NiCad, so the companies will not sell the batteries. 

Bosch produced a line of NiCad called Blue Core Technology.  This adds 50% more to the battery life while allowing the user to recharge the battery in 30 minutes instead of 60 minutes.  Bosch created rods inside the battery that cool the battery as it charges, allowing a quicker charge.

Nickel Metal Hydride (NiMH) – NiMH is a newer battery that manufacturers started to experiment with.  In terms of run time and amps, they have a slight advantage by going up to 3 amps while the NiCad is 2.4 amps.  Because they can have more Amps, they have a longer run time than the NiCad.  Another key advantage to NiMH is they are lighter than the NiCad.  The NiMH has downsides such as they are very temperature sensitive. They will not work below 32 degrees Fahrenheit and degrade quickly with temperatures above 105 degrees.  NiMH have a shorter battery recharge life.  Which means you basically have to buy two batteries for everyone NiCad battery.  Manufacturers argue that because they have longer run time between charges, they basically have the same total work hours as the NiCad.

Lithium Ion (Li-Ion) – Newer technology (used in cell phones, cameras, and other small electronics) cost more, but offers longer run time, lighter weight and are not temperature sensitive.  All power tool manufacturers have moved to this technology.  Milwaukee was the first company to produce Lithium-Ion batteries in their V28 battery platform.  The key advantage to Lithium is they produce the same power through the whole discharge of the battery.  While older technology batteries will lose power gradually, the Lithium-Ion batteries will not.  

The one problem with Lithium batteries is they are extremely volatile and need to be controlled with a reliable circuit board.  There is a circuit that balances the cells when in use and charging.  This balance makes sure all the cells are working as a team, and one not harder than another.  This will help even the wear and provide longer use.  However, the circuit actually presents one downside.  NiCad and NiMH can cool their tools through the design of the tool, while Li-Ion is dependent on the circuit.

*** You should know that there are three types of Lithium Ion batteries.  The three types are: Cobalt,  Manganese, and Phosphate.  You can read more about Lithium Ion Batteries Here.

Battery Myths

More volts and amps in the battery mean the power tool is stronger and better.

False, actually the motor, transmission and other components that produce the power also have a great effect on the tool's performance, along with the quality of the magnets in the motor, metal gears, and the chuck that transfers to the bit.  Basically, it is everything from the battery to the blade or bit, to how efficient it can transfer the power.  While battery voltage and amps does tell a lot about the tool, it's not everything.

Batteries have a memory

This is false, but it use to be true.  Back in the 80's when battery technology was just getting started, a battery did have memory.  Nowadays with new technology, manufacturers have developed batteries with no memory.  So currently this is a myth. 

Draining a battery all the way will actually cause more harm to the battery than good.  When you drain a battery all the way, you can actually damage cells and they will no longer hold a charge. Consequently, you might only be using 11 cells instead of all 12 cells. This lowers your power and battery life.  Because Lithium batteries use circuit boards to monitor the discharge, the technology will not allow the battery to fully discharge and ruin the battery.

Keep Batteries in the freezer

Sounds goofy, but I have seen contractors bring a cooler with ice packs to the job sites.  This will not help your power tool batteries.

Batteries can be rebuilt

Some people say yes and some no.  I have read a lot about this and still get both answers.  The best thing to do is take them to a store and recycle them.  With older NiCad batteries, yes you could rebuild them.  With newer Lithium batteries, I wouldn't even try.  Yes, I know people do, but Lithium is a very volatile battery and why mess with it.  You are better off spending a couple extra dollars and getting an OEM battery. 

Battery Tips

  • Consider what the tool will be used for.  Volts help, but it is not everything.  The tool is just as important.
  • Heat hurts batteries.  Normal heat from use is OK, but don't do anything to create more heat.
  • Keep your battery in a charger will not hurt them.  Battery technology and chargers have come a long way.  A charger will not make them explode.
  • Do not leave Lithium Ion batteries in cold places, as they will not operate at peak performance.

Helpful Terms

  • Cycle Life – The number of times a battery can be charged and discharged. 
  • Total Working Hours – The raw number of hours a battery will work before it will not accept a charge.
  • Amp Hours – Energy hold or gas tank.  Higher amps is a bigger tank and will run longer.
  • Volts – Horsepower, the more volts the more work.