chargers that we use for Electric Model airplanes, have technology that we only dreamed about ten years ago. They sense Internal resistance of the cell, charge at full capacity until the cell gets to 90 percent, then drops the charge rate for the last few milliamps...as the top end is where the cells are damaged in a fast charge, but you can get 90 percent very quickly. some of the chargers are less money cost wise, than one set of batteries. i have three of the up to ten cell chargers that I purchased for less than a set of decent nimh batteries. At the moment I use Lithium ion batteries to power one of my midi accordions.....they give me roughly 10 hours play time...and the advantage is, if I charge them today, and don't use them for a month or two, they lose nothing in storage. I say roughly 10 hours, but I have not ever run them down to where they need a charge before I change them...I just put a fresh pack in every Gig. I have though played over ten hours on a charge and still register 60% on my battery checker.
being heavily into electric powered Rc airplane models BIG ones...I have become fairly up on batteries in the last 25 years.
todays chargers also sense battery temp. and if the temp goes high, they shut down automatically. When you hook up, the charger will tell you if you have a bad cell.
