Batteries can be very important to a self reliant situation. We will deal with lead acid and sealed lead acid types, and the small AA, C, D types, as related to this subject. Some of these you are going to use anyway, so having a plan for storage or recharge isn't a waste of time. First, the small flashlight type applications.
The AAA, AA, C, & D battery choices have come a long way since the carbon type batteries that leaked and corroded whatever they were used in. The alkaline, NiCad, and NiMH chemistries available for these small batteries offer much better longevity, power density, and for some, rechargeability. A good program would probably involve a mix of alkaline sizes bought in bulk (when on sale, obviously), and some rechargeables along with AC and DC powered chargers. The quality alkalines store well, and usually have a 'use by' date on them. The best deals are usually bulk packs of 10, 20 , 40 etc., from a Price Club/Costco type outlet, or watching the ads from various stores, particularly around Christmas. Routinely changing the batteries in the several quality flashlights (like a Mag-Lite, the construction of which allows double duty) you should have around, rotates the stock over time, and keeps fresh batteries in the device, for the occasion when you need it.
The rechargeables, NiCad and NiMH, have their uses, and their peculiarities. The NiCads were first, and have a tapering internal discharge that occurs over time (when not used), and a tapering discharge output voltage (the flashlight gets dim). They also have a memory effect which can develope, and reduce their available output power, unless corrected. The NiMH chemistry came later, and has a relatively flat internal discharge, where the voltage drops off rapidly near the end of the storage/use period (the flashlight goes out). The storage time tends to be shorter for the NiMH, so they recommend their use in devices that are used frequently, and recharged frequently. These both have their places, again selecting quality batteries of higher capacity (mah). Good chargers are available for both types, and charging options for purposes of self reliance will be covered in the charging and solar sections.
Traditional lead acid batteries, a.k.a. wet cells or flooded cells, are very prevalent, both in starting and deep cycle versions. For self reliance applications, deep cycle types would be more appropriate, excepting the starting batteries for the generator, ATV, 4WD, or any other similar application. Most deep cycle batteries can be used for starting applications, and many are rated with cranking amps, CA, or cold cranking amps, CCA, right on the battery. Starting batteries don't last well in deep cycle applications, possibly lasting only several deep dicharge cycles, because the plates are so thin. Using a starting battery in a short term emergency as a deep cycle, is viable, and sometimes necessary, but to plan on it for your self reliance program is not wise or recommended. Flooded batteries require checking the electrolyte level every so often, topping off with distilled water if necessary.
Flooded cells may have a beneficial characteristic for our purposes: they are available dry (acid not added yet). You can get a non activated battery, and an acid pack, and if you keep the battery sealed from a moist environment, it would be a new battery with full life expectancy when activated. They develope some voltage when activated, but do need a full charge cycle.
Flooded lead acid batteries have a higher internal discharge (self discharge) rate than a sealed battery, because of the lead alloy used. This can lead to sulfation on the plates, which will decrease battery capacity over time, and lead to premature failure if not addressed. Keeping them fully charged when not in use, by a routine charging cycle, or using a floating charger, helps with this. Also, the electronic desulfation devices (such as the PulseTech units which we will be offering shortly) are excellent for eliminating the sulfation issue. Bottom line - don't throw an activated lead acid battery, sealed or otherwise, in the back of the garage and forget about it, and expect it to be viable when the storm hits in 3 years.
The sealed lead acid batteries, Absorbed Glass Mat (AGM), and true GEL, are more expensive than wet (flooded) batteries, but have some advantages. The internal discharge rate is much lower in the sealed types, and though they still may sulfate, it is at a slower rate. They do not need water levels checked, and don't corrode around the terminals, because there is no escaping gases under norman use, making them safe for indoor use or storage. Betwen the AGM and Gel types, the AGM would probably be preferable to use, since they don't require a special charge profile as a Gel does, and can be charged from alternator output if necessary. A couple of good examples of high performance AGM batteries to have around the house/shop are a yellow top Optima, and any of the Odyssey batteries. They perform well, can be deep cycled (up to 400 times for the Odyssey), can be used for starting batteries, jumper batteries, etc., and all we ever tested were well above the advertised ratings (CCA). They are not cheap, but can be used for a variety of things until the time comes.
As with any lead acid battery, the sealed types need to be maintenance charged occasionally, or float charged. They will last a long time in standby mode. If they do become sulfated, they can be desulfated with the PulseTech devices mentioned earlier. For more information on amp hour ratings and how this applies to storage and available power, see the regular battery tutorial. The batteries for the trolling setup in your bass boat qualify for this purpose, as do any storage batteries in an RV or toy trailer, as long as you keep them up, and fresh (if they are 5 years old, that is not fresh).
An appropriate quantity of AAA, AA, C, or D batteries, depending on your device needs, in both alkaline and rechargeable, date checked or rotated as needed, to be fresh. One or two deep cycle batteries of at least 75 amp hours, kept on a solar maintainer or float charger (unless you have a non-activated wet cell and acid pack). More storage capacity in amp hours is required for longer term, or high amp load discharge use.