Adjustable power supply to charge tool batteries

A reliable power tool battery is essential for anyone using cordless tools, whether for professional work or DIY projects. However, improper charging habits can lead to shorter battery life, weaker performance, or even dangerous situations.

Use a charger specifically designed for NiCd or NiMH chemistry. Avoid overcharging; remove the battery once it's fully charged. For NiCd, fully discharge before recharging to reduce memory effect. For NiMH, avoid full discharge to prevent capacity loss. 2. Charging Li-ion Batteries Use a smart charger that stops charging once full.

Here's how to charge them correctly: 1. Charging NiCd and NiMH Batteries Use a charger specifically designed for NiCd or NiMH chemistry. Avoid overcharging; remove the battery once it's fully charged. For NiCd, fully discharge before recharging to reduce memory effect. For NiMH, avoid full discharge to prevent capacity loss.

You can also use the power supply to equalize a lead acid battery by setting the charge voltage 10 percent higher than recommended. The time in overcharge is critical and must be carefully observed. (See BU-404: What is Equalizing Charge) A power supply can also reverse sulfation.

Charging nickel-based batteries with a power supply is challenging because the full-charge detection is rooted in a voltage signature that varies with the applied charge current. If you must charge NiCd and NiMH with a regulated power supply, use the temperature rise on a 0.3–1C rapid charge as an indication of full charge.

If you have just a constant voltage buck converter all you can do is adjust the voltage. That's good enough to power all kinds of cool and interesting and awesome loads, but it's not good enough for battery charging. For battery charging you have to be able to set both the voltage and the current.