Battery care for power tool users

—Sponsored article by Fein Canadian Power Tool Company

Manufacturers know equipment reliability is one of the most important contributors to an efficient and cost-effective shop floor. Not only is it important to select the right tool for the job, it’s just as vital to keep the tools in top operating condition.

Good maintenance and power tool care often hinges on the battery. Fein Canadian Power Tool Company offers answers to some common questions heard from manufacturers in industries such as automotive, metalworking and shipbuilding:

How should batteries be stored?
NiCd/NiMH batteries should only be stored for long periods in a fully-charged state. Recharging is needed at least every three months as the batteries will self-discharge.

If the tool won’t be used for a long time, should the battery be removed?
Yes. Even when the device is switched off, a little current may flow. Over time, it will result in total discharge. This will damage—and in extreme cases—destroy the battery.

What is self-discharge?
If it isn’t used for three months, an NiCd/NiMH battery will lose around 60 per cent to 80 per cent of its charge. The figure for lithium-ion batteries is three to five per cent per month. Self-discharge is temperature-dependent and increases with temperature. Room temperature is ideal for storing tools.

What is total discharge?
Total discharge means squeezing out the last drop of current from a battery. The battery’s voltage then falls to 0 V. If this status is maintained, chemical reactions occur at the electrodes in the battery, which render them partially or totally unusable. As a result, the battery loses huge amounts of capacity and in extreme cases, can’t be charged any more. Therefore, avoid discharging batteries below a type-dependent final discharge voltage.

NiMH batteries are not suitable for use at temperatures below 0°C. They show signs of significantly reduced capacity even at temperatures close to freezing and are totally unusable below approximately −10°C. NiCd batteries are suitable for use down to -10°C.

What is the battery service life?
NiMH batteries can be charged 400 to 700 times; NiCd batteries can be charged roughly 500 to 1,000 times and Li-ion batteries up to 1,000 times (depending on capacity). These figures are only attained under optimum conditions, however. Depending on how the battery is treated and cared for, lower figures may apply. Battery capacity decreases over the battery’s life. Batteries with less than 70 per cent nominal capacity are generally considered to be worn out.

What does memory effect (for NiCd technology) or lazy battery effect mean?
The battery records how much it has been used. If the battery isn’t fully discharged before charging, small crystals form on the electrodes and make it harder to charge.

If you fail to fully discharge the battery several times in a row, you’ll experience shorter and shorter availability times. With NiMH technology, you might experience a ‘lazy battery’ effect, similar to the classic memory effect.

Lithium-ion batteries and lithium-ion polymer batteries can and may be recharged at any time. These batteries don’t experience any kind of memory effect, but you should avoid charging for short periods too often.

Can I reverse the lazy battery effect?
If the capacity of the NiCd battery decreases over time, it can be restored by reconditioning: fully discharge the NiCd battery (don’t go quite as far as total discharge), fully recharge and repeat several times. Each time this cycle is repeated, it improves the power output. For NiMH batteries, a refreshing device is needed.

Can batteries be repaired?
Batteries can’t be permanently repaired to a high quality. Even if other providers claim they can repair batteries cheaply, the results will be short-lived because the new cells aren’t matched to existing components. FEIN and its agents offer long-term quality. We always replace defective batteries.

FEIN has been a world-leading power tool manufacturer for over 140 years. Fein Canadian Power Tool Company, located in Mississauga, Ont., provides a range of high-quality power tools and accessories. Visit www.fein.ca for more information.

To view more articles on power tools and battery care, see the Technology Showcase