The methods to safely and effectively re-charge batteries vary considerably from type to type. I would recommend that you become very familiar with the techniques that are supposed to be used for the NiMH batteries you have. The best source of information is from the battery manufacturer within white papers that they have written regarding their own technology!!

There are a number of things to keep firmly in mind regarding re-charging...

** Many consider the subject childs play and think that simply a wire connected to a voltage source constitutes a charger.

** There are many that portray themselves as experts in the field when in actuality they are all wet.

** Many think that all batteries charge alike similar to the of attaching a clip on charger to the 12V lead acid unit under the hood on an automobile.

** There are dozens of commercial battery chargers on the market that claim to be made for one particular type of cell technology or another and in the end these same units end up destroying your cells. (I have disassembled some of these units, traced the circuits, and confirmed this to be true).

** And lastly keep in mind that whilst the manufacturers of cells are in the best position to offer effective re-charging information that it is still common for them to private label or endorse a battery charger technology that ends up curbing the life time of their cells. (After all their main goal is to sell batteries and not chargers).

Michael Karas

PS. You may want to consider researching the subject from the aspect of companies that make support chips for charging and monotoring batteries. These companies have some excellent applications notes on the subject of various battery charging techniques. TI and Maxim are two places to start. (Look for info regarding TI's BQ2014 and BQ202 devices for example).

The information provided at this link:

http://www.powerstream.com/NiMH.htm

...is a good start on the path to understanding NiMH charging. The discussion there is a no-nonsense, on the mark discussion of the subject.

Michael