Over time rechargeable batteries of various chemistries will lose their ability to hold a charge, and thus you tend to put them in a dark cupboard (or worse) and move on with life. However in some cases, you can restore them with a desulfating circuit. This process has been described by Instructables user "technovative" and includes the sketch, circuit and some sample output captures on a CRO, for example:
There is a possibility that these methods could be dangerous, so please heed the advice of the author with respect to the battery type you can use and also seek your own advice. However it's an interesting concept and may prove useful, so click here to find out how it can be done. And for more, we're on twitter and Google+, so follow us for news and product updates as well.
If you'd like something that's much more fun and quite safe - check out our Experimenter's Kit for Arduino:
The package includes a wide variety of parts, sensors and modules including: a servo motor, lights, buttons, switches, sound, sensors, breadboard, wires and more. Furthermore a Freetronics Eleven Arduino-compatible board is included to make this an extensive hobby experimenter, inventor and starter kit. However we don't leave you alone to figure it all out, included is a great project and instruction booklet, plus access to a supporting web page and software examples. In other words - this is everything you need to get started for a fun range of electronics and Arduino related projects!
So to get started or for more information and to order, check out the product page.