To recondition a rechargeable battery, you have to discharge it rapidly, then slowly squeeze every bit out of it before attempting to recharge it. Msuzuki777′s battery reconditioner uses an Arduino, some spare parts, and basic electrical theory to automate that process.
This particular reconditioner only works with AA and AAA rechargeables, but the design could be modified for mobile phone batteries or any others you may have lying around. It may not save time, but it’s a DIY project that will definitely save money.
Battery Reconditioner [Instructables via Hack a Day]
Tim
Tuesday, June 28, 2011 at 6:01 PMI wouldn’t suggest this for mobile phone batteries. While Rechargeable Alkaline, Nickel Cadmium and Nickel-Metal Hydride batteries all have a ‘memory’ of sorts and can be reconditioned like this, Lithium Ion and Lithium Polymer batteries actually suffer from any discharge at all, especially below a certain point. This would only cause any modern mobile battery damage.