Lithium Ion Batteries: The Future Of Power And Portability

If you live in 2013, the odds are almost 100% that you rely on rechargeable batteries.  Cell phone, computer, that cute little mustache trimmer you keep next to the sink.  And, of course, power tools.  No matter what you use rechargeable batteries for, the objective is always the same - getting enough power to do the job anywhere you need it.

Now, more than ever, that demand is impacting the entire power tool industry.  Drills, saws of all kinds and even impact wrenches are flooding the cordless power tool market from all sides.  Every major power tool manufacturer has launched battery-powered models.  A new rechargeable battery industry has emerged in the last decade just to support the need for more, longer lasting power.

Battery Basics

Lithium Ion Battery: Ryobi Lithium Ion power tool battery and recharger.Lithium Ion Battery: Ryobi Lithium Ion power tool battery and recharger.A battery is basically a place where you store electrons for later use.  You start by loading up the battery with billions and billions of electrons.  Then you flip a switch and the battery lets those electrons flow out into your cell phone or your power drill. The rechargeable kind allows you to load up more electrons when you run out.

All batteries rely on some kind of internal chemistry (cell type) to accept electrons, store them, and release them.  It is this chemistry the gives the battery most of its storage and release ability.  Different chemistries are used for different charge-release needs. Car batteries need to pump a LOT of electrons out at one time to crank your car. They use Lead-Acid chemistry.  On the other end of power consumption, the most popular cell phone batteries, which need a long-term, low-voltage slow release process, are Nickel-Metal Hydride (NiMH). They have a great usage cycle, and can be quite small.

Power tools need some of the muscle of a car battery, but they also need the long-term usage of a cell phone battery.  There are two dominant power tool batteries in use today - Nickel Cadmium (NiCad) and Lithium Ion (Li-Ion). The NiMH chemistry has similar capacities as the NiCad but it does not tolerate extreme work conditions so it is not used much in heavy duty power tools. While NiCad has owned the power tool market for about 15 years, Li-Ion is fast emerging as the cream of the rechargeable crop.

What’s So Great About Lithium Ion Batteries?

Energy Density Comparison: Energy Density comparison of the most commonly used rechargeable battery chemistriesEnergy Density Comparison: Energy Density comparison of the most commonly used rechargeable battery chemistriesWhen it comes to the portable power needed for heavy-duty tools, the battery objective is to generate maximum Energy Density.  This is the amount of energy than can be stored in the battery. The higher the energy density, the longer the charge will last.  Li-Ion has the best energy density of commercial power tool batteries AND it has superior energy to weight ratio.  They deliver the same power as the NiCad counterparts, but are about half the size and weight.  They cost about 20% more right now, but that will change when these batteries become more widespread.

Li-Ions also have a very slow self-discharge rate (aka “charge loss”).  They retain their charge when they are not being used. After a couple of months (sometimes weeks) of storage, NiCads will lose almost all of their charge.  Consequently, if you want immediate use of the tool, you must keep it on a charger full-time.

But the very slow rate of charge-loss in Li-Ions means they maintain most of their charge for longer periods, up to six times longer than a NiCad. They can also be recharged about twice as many times as a NiCad before their chemistry depletes.

The Future Of Rechargeable Batteries

Swamp Rat #37 Attempting World Record: The Lithium-powered dragster, designed by Lawless EV Racing, boosts over 1200 hp.Swamp Rat #37 Attempting World Record: The Lithium-powered dragster, designed by Lawless EV Racing, boosts over 1200 hp.NiCad is the current standard for rechargeable power tool batteries.  But there are no new frontiers with NiCad chemistry.  It has achieved its peak, and it’s going to stay that way.

Lithium technology is where the big money is going.  Driven by remarkable success in the automotive, defense and airline industries, Li-ion technology is drawing huge interest and HUGE investment.  As the quest for small, powerful, long-use, fast-recharging batteries heats up, Lithium Ion will be front and center.  If it works for dragsters, it's going to be awesome for power tools.


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Mar 2, 2013
by Anonymous

What about lithium polymer?

What about lithium polymer? I know those are kind of unstable, but some phones are using them I believe!