Cordless Tools Powered by Lithium Ion
Grainger Workbench Ep. 5
Lithium-ion technology is continuing to redefine the cordless power tool industry. As tool manufacturers continue to search for that “Holy Grail” of the perfect power tool, advances in battery technology keep changing the game.
Lithium-ion battery technology is considered to be one of the biggest innovations in nearly 20 years. Its use in cell phones and laptops has driven weights down and run-times ever higher.For cordless tools, the NiCad technology has been entrenched for years. The 18-volt NiCad continues to be the best balance between performance, weight and price. However, the improved features of lithium-ion is replacing its NiCad counterpart.
Lithium-ion offers one of the best energy-to-weight ratios and a slower loss of battery charge when not in use. As professionals continue to demand more powerful, efficient and comfortable tools to work their trade, lithium-ion seems to fit the bill.
You Can Use:
More Power/Less Weight
Just like in cell phones and laptops, the lithium-ion battery is providing more energy in a lighter weight tool. We really don’t think about this feature when we use cell phones or laptops. But for a professional contractor using cordless tools all day, the lithium-ion battery can provide extra benefits. With more power, they can get the job done faster. Less weight means less fatigue and stress on the body. The result can be improved productivity.
No Loss of Power
Anyone who has used a NiCad cordless tool has experienced the dramatic dip in performance near the end of the battery discharge cycle. Lithium-ion provides a consistent level of performance from the beginning to the end of the cycle. With more consistent power, the job can get done faster. To a professional contractor, time is money.
Older NiCad batteries suffered from “memory effect.” That is, a battery will no longer charge to full capacity after being partially charged and discharged a series of times. However, improvements have been made to the NiCad battery technology that eliminates this problem. With lithium-ion, users can recharge their batteries to full capacity at any point in the discharge cycle without causing cell damage. Typical lithium-ion batteries also have a low self-discharge rate of 1.25% - 5% per month compared with over 10-30% per month in common NiCad batteries.*
Advances in Technology
Many researchers and companies are still working on improvements to the lithium chemistry. The focus is on cycle life, output power and safety. These improvements are made by experimenting with chemical formulations. As these formulations change, additional cordless tool features may be developed.
Cordless tool manufacturers are attempting to distance themselves from their competitors by adding features to the tool/battery product. These include:
- Battery fuel-gauge – displays remaining run-time to let user know how much charge remains before starting a job
- Slide pack battery design – easy-to-use design that provides a more secure fit to the tool
- Impact and vibration protective rubber on the battery housing – helps protect battery cells and packs during accidental drops
- Motor redesign – new 4-pole efficient design optimizes size and weight for use with lithium-ion technology
- Ergonomics – improved grips and better balance helps reduce strain on the user
As an example, Milwaukee Tool has an exclusive Digital Power Management (DPM) feature to their lithium-ion 18-volt power tool line. The features of the DPM include overload protection, temperature management system, individual cell voltage monitoring, cell discharge protection and a battery fuel gauge.
These types of design features can help extend the cycle life of a battery and reduce the number of replacements needed making lithium-ion a worthwhile investment.
Guidelines For Prolonging Lithium-ion Battery Life
Here are some tips and guidelines for you to follow. Lithium-ion batteries:
- Should not be fully discharged frequently
- Should not be depleted to below their minimum voltage (2.4V to 3.0V per cell)
- Should be kept cool. Aging will take its toll much faster at high temperatures
- Should not be used in temperatures below 0 F.
Users can be expected to migrate to the lithium-ion technology to experience the benefits of more power, increased run times and lighter weights. In the meantime, professional users have a wide choice of the cordless tool voltage spectrum – from the workhorse 18-volt NiCad to the more efficient lithium-ion at lower (10.8 volts) and higher (36 volts) capacities.
Source: Milwaukee Tool