For most uses, rechargeable batteries are more effective, economical, and better for the environment than disposable alkaline batteries. Regardless of battery types, all batteries purchased at MEC can be returned to the store for recycling.
Disposable batteries are less economical over time, than rechargeables. They are however, recommended in safety-related devices such as avalanche transceivers because their power output declines slowly and predictably. The sudden power drop or NiMH or NiCad batteries can prevent built-in power level indicators from giving adequate warning of battery failure.
Given equal power output and run time, NiCads are about 25% lighter than SLAs. You can expect around 700 or more recharge cycles depending on usage. They don't mind deep discharge, and perform better than SLAs at low temperatures. Today's industrial grade NiCad batteries do not suffer from memory recharge problems, but over time they can develop crystals that reduce their capacity. Most experts recommend that you periodically cycle these batteries through a complete discharge or full charge cycle. Be aware that toward the end of their supply, they go from good power to zero power rather abruptly, a rude surprise if they are your sole source of light or energy.
Their performance is similar to NiCads, but they provide a power-to-weight saving of 25 to 40%. They are more robust and can be recharged at any point in the discharge cycle. Moreover, they are much less toxic during the recycling process. Unfortunately, not only will you notice these benefits on the trail, but also in your wallet: NiMH batteries are fairly expensive. They also lose their charge faster than other types, whether or not they are in use. If stored for more than a week, they should be topped up before use.
Capacity of rechargeables is measured in mAh (milliamp hours) or Ah (ampere hours). For comparison, 1000mAh is equal to 1Ah. Given the same current draw, the higher a battery's capacity, the longer it will run between charges. But, it will take longer to fully charge a high-capacity battery.
Get more details on MEC's battery recycling program