Carry rechargeable spares, that should take care of your runtime. Buy the highest quality batteries and charger you can afford that meets your needs. Rechargeables are fine for blinkies, less cost long term, and less waste versus alkalines.
Don't overthink discharge rates, putting them in a refrigerator won't help unless you're not using them for 6 months. A good charger will minimize those drawbacks and maximize the performance and lifetime of your batteries.
Last edited by flipped4bikes; 11-07-07 at 10:50 AM.