Which kinds of batteries do you have to be concerned about memory? I know on ni-cads i.e. my electric tooth brush, I am supposed to run it all the way out every six months. Why does it not hold the memory after each use? Is is okay to charge my cell phone (li-ion) each day or should I let it run out completely? What about the other rechargebles: lead acid and Nickel Metal Hydrid? (and any others you know of). Thank you. Tom.

Do a search on the web. BatteryUniversity and several others I can't think of off hand will tell you more than you ever wanted to know.