Secondary (Rechargeable) Batteries
Secondary batteries are the rechargeable batteries. They have the advantage of being more cost-efficient over the long term, although individual batteries are more expensive. Generally, secondary batteries have a lower capacity and initial voltage, a flat discharge curve, higher self discharge rates and varying recharge life ratings. Secondary batteries usually have more active (less stable) chemistries which need special handling, containment and disposal. Ni-Cd and small-size lead acid batteries require special disposal and should not be simply thrown away.
Best solution for high drain applications
For high utilisation applications the cost of the charger is soon paid back.
Cost of charger. For low cost applications such as toys the charger could cost much more than the product it supports.
Safety issues with mains power.
Lower energy density than primary cells unless exotic chemistries used.
Lack of standards
Many custom pack designs and limited interchangeability. (Disadvantage for the user but creates a captive aftermarket for the manufacturer)
Typical Battery Chemistries
Nickel Cadmium (NiCad)
Nickel Iron (NiFe)
Nickel Metal Hydride (NiMH)
See also Primary Batteries and Alternative Energy Storage Methods