Cordless tool manufactures have embraced Lithium ion battery technology for their cordless tool battery packs. Most of the 14.4 volt and up battery packs use Lithium ion batteries.
There are several advantages to Lithium battery chemistry.
- Lithium batteries do not suffer from ‘memory effect’ like NiCad and to a lesser degree Metal Hydride batteries do.
- The recharge time is considerably less. DeWalt’s 18 volt and up batteries recharge in 1 hour. Try that with NiCad battery pack.
- Lithium batteries doe not need to be deep cycled. Deep cycling can actually shorten the lifespan of the of the battery pack.
- Provides more power for the same density of material.
With all of the advantages of Lithium batteries, there must be some down sides to these batteries. There are a few significant limitations with Lithium battery chemistry.
- Lithium batteries have a defined life time, which starts when the battery is manufactured, not when it is first charged up.
- If Lithium battery packs over heats it can explode.
- The warnings about not short circuiting battery packs are very valid especially for Lithium battery packs. It will cause the Lithium cells to explode. Most of the battery packs have circuitry to prevent a dead short.
Why does the Lithium ion battery have a defined life span?
The electrolyte slowly consumes the positive plate and the electrolyte decays. This chemical change causes the internal resistance to increase. In time, the cell resistance is raised to a level where the battery can no longer produce electricity.
The Lithium ion batteries prefer a shallow discharge. Partial discharges produce less wear than a full discharge. The capacity loss per cycle is minimized.
With that background here are some guide lines on how to extend the life span of your Lithium ion battery pack.
- Charge the battery pack often.
- Try to limit the number of times the battery pack is fully discharged.
- Do not fully charge the battery before extended storage time.
- Store the Lithium ion battery in a cool place. Most manufactures 59 degrees Fahrenheit (15 degrees Centigrade).
- Never freeze a Lithium ion battery pack. It will not help restore it. There is no known external method to restore a dead Lithium ion cell.
- When purchasing replacement battery packs, pay close attention to the manufacture date. Older battery packs will give you less working time before the die.
