Apogee Powers Ahead With LiFePO4 Battery-driven Tools

Increasing popularity of a variety of portable electronic devices, including notebook PCs, mobile phones, PDAs, netbook PCs, PNDs, mp3 players, etc., has helped to foster the development of practical, green power sources over the past few years. Among the most widely-used is the lithium-ion battery, which, able to be combined with cobalt, manganese, nickel and iron phosphate, is vastly installed in electric cars, electric bicycles and handsets. Now, Li-ion battery has found one more application in Taiwan's power tool segment, with Apogee Power Inc. having launched the island's first power tool driven by Li-iron-phosphate (LiFePO4) batteries.

Taiwan is gradually gaining ground in the global supply chain of power tools, such as power screwdrivers and drills, ranking among the world's top-10 power tool exporters in 2007. Most Taiwanese makers tend to be OEMs (original equipment manufacturer) or ODMs (original design manufacturer), due mainly to deficient sales and marketing capabilities, such as having inadequate distribution channels and poor consumer recognition due to weak branding. However, having excellent production and R&D capability enables Taiwanese suppliers to be sought-after contractors for international, major brands as Bosch, Stanley and Black & Decker.

Drawing on its expertise in electric circuit design and R&D of power management solutions, Apogee, also known as National Energy Technology Co., Ltd. in the battery solutions segment, has successfully built LiFePO4 cells and its independently- developed Ultra Capacitor in the production of battery packs for power tools, and unveiled a couple of power screwdrivers and drills under its own label this year, setting the works in motion to develop more power tools driven by the most stable, safest and eco-friendly energy source in the industry.

Innovative Move

There are good reasons why few power tool makers in Taiwan believed that LiFePO4 batteries can drive power tools, until Apogee proved it can be done. According to Went Lin, general manager of the firm, generally Taiwanese makers only use lithium cobalt or lithium manganese batteries, mainly because LiFePO4 cells supplies 3.2V, less than 3.5V generated by others. In other words, it costs more to use bigger quantities of LiFePO4 cells, and, above all, suppliers have to redesign the whole body of power tools to hold a larger battery pack. Hence, Apogee has made a breakthrough of sorts by using LiFePO4 batteries in power tools, and for justifiable reason.

Asked why Apogee opted to build LiFePO4 batteries to drive power tools, Lin answered that the power source is safer than lithium-ion batteries that has cobalt and manganese as cathode, because the strong chemical bond between the phosphorus and oxygen in the phosphate (PO4) reduces oxygen emission to avoid possible explosion of LiFePO4 batteries. In comparison, lithium cobalt batteries aren't reliably safe when discharged in electronic devices, while lithium manganese batteries can overheat when discharging, or even ignite if overcharged.

Very Green

One of the eco-friendly features of LiFePO4 batteries is significantly longer lifespan, which can be discharged and recharged for around 2000 times, quadruple that of lithium cobalt and lithium manganese counterparts. Such capability, especially in an era where millions of electronic devices are tossed yearly, is not only more convenient, enabling less frequent batter replacement, but also green, according to Lin.

Plus, LiFePO4 is non-toxic, non-contaminating and RoHS (Restrictions of Hazardous Substances) approved as entirely harmless to the environment. "Enhanced safety, extra-long lifespan and green make LiFePO4 batteries a promising power supply solution," he said.

The firm's efforts to develop LiFePO4-powered power tools have piqued intense interest among Japanese and European buyers.

But LiFePO4 batteries still has an inherent weakness: having comparatively low energy efficiency as a power source for tools, which call for peak-power delivery instantly to achieve high torque. The solution is, Lin said, to use more batteries, which results in the dilemma of having to raise prices due to a bigger battery pack and giving users unwanted bulk. Fortunately, Apogee's Ultra Capacitor untangles such dilemma.

How It Works

The Ultra Capacitor is developed in-house by Apogee's founder Dr. C.K Tsai, Ph.D. of the University of Texas Austin, as a solution to prolong the lifespan of all lithium-ion batteries, according to Lin. He explained that, while operating electronic devices, a lithium-ion cell is subjected to high power pulses or current discharge pulses, causing rapid capacity degradation-the reason why the service life of lithium- ion cells is short and battery capacity slowly diminishes with time.

The Ultra Capacitor features a proprietary ceramic coating system inside, which is highly conductive and corrosion-resistant, with the pore size in the range of 50 to 100 angstroms. Coupled with a highly conductive electrolyte, this capacitor helps to produce 100 times higher power-to-weight density than a conventional lithium-ion battery, and offers 100 times greater energy density than an electrolytic capacitor.

The capacitor's energy boosting capacity enables the reduction of battery pack size and provide peak current shaving for enhanced battery performance and extended service life. Able to be configured in series or parallel circuits and stay optimal over a wide temperature range from minus 55 to plus 70 Celsius, the capacitor is quite multifunctional.

Lin said that most lithium-ion batteries are specifically designed to offer high power pulses, and, however, are usually compromised to a lower energy-density tradeoff. Therefore, Apogee's Ultra Capacitor, being very compact and highly efficient to boost battery performance, can help to alleviate such shortcoming. Most consumer surveys, he added, show that beefed-up battery packs play a decisive role to sway consumers to buy an electric product.

Extra-long Operation

Installed with LiFePO4 batteries and Ultra Capacitor, Apogee's power tools feature standard voltage output of 14.4V and over six-times as long in operation time relative to competing models powered by nickel cadmium batteries, or twice as long as other LiFePO4-powered tools. Also, it is remarkable that Apogee's power tools, while providing enhanced torque with beefed-up performance, weigh less than 2kg, according to Lin.

Lin said that his firm has applied such capacitor technology to enhance performance and electrical storage in solar panels, some of which have been used to develop special tool caddies that can help users to recharge battery.

"Apogee is concentrating on high current pulse applications, aiming to put its cutting-edge capacitor technologies, including the world's first IC chips to protect lithium-ion cells, to good use," Lin stressed. "We have also started to contact carmakers and car-repair shops to promote products as well as carve out niches. Meanwhile Apogee does not see immediate threat against our technology and commercialization of a competing system well into the future."