If you use a Ni Cad charger, or a charger for any other type of battery, they could possibly explode. The new alkaline chargers recharge the batteries in a very slow controlled manner, while monitoring the battery, and do it quite safely and effectively.
One thing people need to realize that WTSHTF electricity may be spotty or non existent, so you have to have a way to power the charger. Another possibility is to round up a bunch of batteries (see video here) and recharge them to have on hand.
Here are some battery chargers that work with Alkaline batteries, and while some have mixed reviews, you should do your homework before you buy one. One charger that costs, say, $30.00 could pay for itself in very little time. Another feature is most of the chargers will do AAA, AA, C, D and 9 volt batteries.
There are a few things you need to do when charging your batteries:
Check the battery to confirm what type it is. It needs to say Alkaline, unless the charger will do all types of batteries.
Always check the batteries for leakage before and after charging, and toss them if they have any.
If you plan on reusing batteries from your devices, don’t let them run completely down. As soon as the device starts to fall off, recharge them. Alkaline batteries come new around 1.6 volts, and if you catch them before they get too discharged, you will be more successful.
One nice thing, most of the new chargers will test the battery and let you know the condition of the battery automatically.
Some of the new chargers will also recharge all other types of batteries as well and here’s a rundown of just some that are available, so do your homework.
Maximal Power FC999 Universal Rapid Charger for Alkaline, RAM, Ni-MH, Ni-CD, AA, AAA, C, D, N, 9V
Viatek RE02G Renu-It Pro Series Gray Professional Grad Disposable Battery Regenerator/Used for AA, AAA, C, D & 9-Volt Batteries
Sierra Electric JB5411 Universal Battery Charger
One final thought, there are all sizes of rechargeable batteries available that can be recharged from a car cigarette lighter port. For WTSHTF, they would be the best option.
http://www.megabatteries.com has a good selection of rechargeable batteries and 120VAC/12VDC battery chargers as well.
Spending a little more and getting a charger that will charge more than one type of battery from a wall outlet or car lighter socket, would be a very handy item indeed.