Power up, nurture and revitalize rechargeable AA and AAA batteries with this sophisticated but easy-to-use battery recharging system from La Crosse Technology. The unit charges all NiCad and NiMH "AA" and "AAA" rechargeable batteries simultaneously, if necessary, and features four different modes to help your batteries along. A charge mode powers up batteries the standard way, a discharge mode discharges batteries and then recharges them for optimal efficiency, a recharge mode discharges and recharges up to 20 times to bring old batteries back to life, and a test mode rechargeable battery charger displays battery capacity. Seven easy-to-use function keys and automatically switches to trickle charge when charging is complete to ensure maximum battery capacity. Four separate LCD displays show progress and capacity. And, a handy overheat detection feature prevents over-charging for longer battery life.
A battery charger can be a source of DC voltage for experimentation. It may, however, require an external capacitor to be connected across its output terminals in order to "smooth" the voltage sufficiently, which may be thought of as a DC voltage plus a "ripple" voltage added to it. To see the difference between industrial battery charger connecting and not connecting a capacitor, connect also an oscilloscope across the output terminals. Note that there may be an internal resistance connected to limit the short circuit current, and the value of that internal resistance may have to be taken into consideration in experiments.
On the other hand, many rumors circulate about the best practices smart battery chargers to prolong battery life. What practices are best depend on the type of battery. It is "rumored" that Nickel-based cells, such as NiMH and NiCd, need to be fully discharged fast AA battery charger before each charge, or else the battery loses capacity over time in a phenomenon known as "memory effect". However, this is only partially accurate: nickel alloy cells can be charged at any point throughout their discharge cycle – they do not have to be fully discharged. Memory effect should instead be prevented by fully discharging the battery once a AA Nimh battery charger month (once every 30 charges).[20] This extends the life of the battery since memory effect is prevented while avoiding full charge cycles which are known to be hard on all types of dry-cell batteries, eventually resulting in a permanent decrease in battery capacity.