Batteries
The Rover uses rechargeable lithium-ion (Li-ion) batteries, which can operate at low temperatures. The batteries are primarily recharged by the solar array.
The Rover's battery cells are rated down to -40C, but their operating voltage and energy capacity are greatly reduced under such conditions, which is one reason for the heaters inside the Rover's body.
Over time, the batteries will degrade and will not be able to recharge to full capacity.