- A rechargeable battery (also known
as a secondary battery) or cell. Common varieties include
the lead-acid accumulator and nickel-cadmium (NiCd) batteries. However, more and more environmentally-friendly
batteries such as NiMH (nickel metal hydride) and NiH (nickel hydride)
are also becoming available.
- A component of a heat pump that
stores liquid and keeps it from flooding the compressor.
The accumulator takes the strain off the compressor and improves the
reliability of the system.