About Lithium Ion Batteries

Lithium Ion Batteries have been in use in the electronics and computing industries for several years already.   These are the preferred form of rechargeable power supply because unlike other battery types Lithium Ion does not develop a memory, doesn't self discharge as quickly and can be made lighter and smaller for a given power rating that other types of battery.

Lithium Ion is Lighter

Each cell in a Lithium Ion Pack is approximately the size of an AA battery and delivers 3.6V, compared to NiCD and NiMH where each cell is C sized and delivers 1.2V.   To make an 18V supply with NiCD/NiMH requires 15 C sized Batteries but willl deliver a battery pack capable of supplying up to 2.4Ah (3.5AH for NiMH).     Lithium Ion Cells generally supply 1.1Ah so an 18V pack is made up of 10 AA sized cells, connected in 2 banks of 5, giving 18V 2.2Ah for the pack.   So instead of 15 C cell batteries to give 18V 2.0AH, a Metabo 18V Li-Ion pack only has 10 AA cells, reducing the weight by nearly 40% plus allowing for more secure mounting for the batteries as well as improved airflow around the cells to prevent overheating.

Lithium Ion Is Stronger

Li-Ion batteries, unlike other types, deliver 100% of their capability from fully charged to completely flat.   A NiCD or NiMH battery will expend nearly half it's charge driving the tool at below optimal because the voltage drops as charge is used.   So using the tools with a battery at half charge means the tool works harder and draws more current from the pack than it would at full voltage.   Li-Ion will supply full voltage and full current right up until the pack is flat.   Because there is no way to recognise the battery is going flat by normal methods, every Li-Ion Pack has a charge indicator built into it to make sure you don't start the job with a nearly flat battery.

Lithium Ion Lasts Longer

Lithium Ion Battery packs do not develop a memory or suffer from " lazy battery" problems.   They can be charged at any part of their discharge cycle without problems.   NiCD and NiMH batteries have a high rate of " self discharge" .   If you fully charge a NiCD or NiMH battery then leave it in the case, it will be flat after approximately 5 months and will begin to suffer damage to the cells.   These batteries are recognised to have a self discharge rate of between 20 & 25% per month meaning that if you don't use the batteries regularly, they will gradually lose capacity and die completely.   Li-Ion doesn't suffer the same problems. With a self discharge rate of approximately 2% per month, you can charge a battery pack and leave it sitting for a year, confident in the knowledge that the pack will be ready for use and still hold nearly a full charge.

Lithium Ion is Better

There are lots of little reasons why Li-Ion batteries will be a major boon for the cordless tool user.   Li-Ion can be used at temperatures between -5 and 50 degrees celcius, where NiCD & NiMH can suffer damage at temperatures above 35 degrees.   Li-Ion tools can be made in higher voltages that NiCD & NiMH without being unusable.   Milwaukee has produced 28V Cordless Tools and Bosch Cordless is now available in 36V.   These voltages are possible thanks to the weight savings of Li-Ion and provide the kind of Cordless Tools that users have been waiting for......tools that will perform as well if not better than their corded counterparts.   The Bosch 36V Rotary Hammer Drill has the same bit rotation speed, higher blows per minute and more joules per blow than the 2kg electric version Bosch has on the market.

 Lithium Ion Is Nicer

NiCD batteries, as the name suggests, contain nickel and cadmium.  Cadmium is one of the nastiest heavy metal toxins on the planet.  Cadmium in drinking water supplies causes physical and mental degeneration and severe birth defects.  NiMH batteries contain pressurised Hydrogen when charging.  Hydrogen is a lighter than air highly flammable gas and can easily ignite from a spark that may be caused by an improper battery connection to the charger.  Li-Ion contains neither of these dangerous materials.  It is better for the environment and better for the people handling it, and much better after disposal.  Regulations also require that a battery pack can be no more than 8% lithium, which explains why the cells are smaller but the battery packs are still reasonably large.

At this point, there is no downside to this new technology.   There is no " trade off" of features or functions for more power. Lithium Ion is stronger, lighter, longer lasting and better than any other form of cordless tool battery on the market.   All tools have been thoroughly tested and reviewed by the manufacturers before being released on the market, but nothing really replaces user feedback, so watch this space.........