Leaderboard

Fairly simple. Assuming all your current batteries are functional and hold charge, buy a cheapest, worst looking, not holding charge battery off ebay for the experiment. Pry the case open, as neat as possible. Consider how you'll glue the case together for the later use - batteries do not have to be pretty, but must fit. Look what's inside. Chances are that it'll be something of a standard size (AA, 2/3 AA, AAA, etc). For the refurbishing, you'd need to solder tabs or wires to the new cells. It is not a big deal. You would need a 20W or bigger soldering iron for that, the bigger the better. The quicker the soldering action the better - do not overheat the cell. Modern NiMH cells are night-and-day comparing to the old cells. The are low self discharge, getting closer to alcalines for that, the capacity is also getting close. The good ones are AmasonBasics and Panasonic Eneloop (former Sanyo). Tenergy are fine, many are already with tabs.There are others too. Any new cell would be better than the old depleted cell.

In my case, as a Chaplain Responder, "Relying on communications equipment for family safety, as well as coordination with other GMRS licensed Chaplains in post-natural disaster situations when phone service is interrupted for days or weeks."

and some photos https://goo.gl/photos/sVnU5TNpzWXnXqFm9