. . . about the charger: most of the inexpensive chargers I see are for 2 AA batteries. The flashlight I have uses 3 AA (am contemplating another flashlight using 3 AAA's). My concern is that the 3 batteries should be charged at the same time for the same duration to prevent damage or early death of the batteries. Is this concern reasonable? Should I look for a charger for 4 AA's?
For the very best in a battery charger for NiMH batteries you are looking for two specific things:
~ First of all you want a smart charger that detects when the cell is charged and isn't just a simple "dumb" charger that just has a built in timing circuit that charges the cell for a set amount of time and then shuts off. Be careful with cheap chargers on that point because some will try their best to pretend to be true smart chargers with lights that change color when the battery is charged and such but on the inside are just regular dumb charger. What you are looking for is a charger that uses "delta V" detection to detect when the battery is fully charged.
~ Secondly it is best if the charger has individually regulated charging slots. There are many chargers out there including many of the smart chargers including the charger made by Enloop that charge the batteries in pairs and are not capable of charging just a single cell or an odd number of cells (such as three cells) but must charge in pairs. This will often lead to slight imbalances developing with one of the two cells in the pair not getting fully charged.
Here are some links to some chargers I know of that are both true smart chargers and that charge the cells individually:
http://www.amazon.com/La-Crosse-Tech.../dp/B0031ERMO4
http://www.amazon.com/La-Crosse-Tech.../dp/B000RSOV50
http://www.amazon.com/La-Crosse-Tech.../dp/B004J6DLD4
http://www.amazon.com/Powerex-MH-C90.../dp/B000NLUSLM
http://www.batteryspace.com/ch-v3150...irectplug.aspx
http://www.batteryspace.com/CH-V9228...-USB-plug.aspx
I personally own a La-Crosse Tech. BC-500, La-Crosse Tech. BC-1000, a PowerEx MH-C9000, and several CH-V3150 chargers. The La-Crosse Tech. BC-500 and the CH-v3150 chargers are the ones I use most of the time and I only end up using the BC-1000 or MH-C9000 units as "reform school" for straightening out "problem child" cells and getting them to behave themselves again.
The CH-v3150 is a cheap charger that is a true "Delta V" smart charger with individually controlled charge slots and it just does its job and does it well without any problems. The BC-500 is a nicer charger with a nice display and some additional functions that can come in handy (think reform school light version capabilities if needed). Either would do just fine for a beginner. I should note that there are other chargers out there that are basically the same as the CH-v3150 some even looking like they came out of the same mold on the same factory line just with different colored plastic and a different logo on them. That is design is basically the bottom rung of the good chargers that have both true "Delta V" intelligent charging and individual slots just without any fancy options or display screens.