Electronic device case

A protective enclosure for a mobile computing device having a rechargeable battery, the protective enclosure comprising:

• a device interface for electrically interfacing with the mobile computing device;
• a supplemental battery;
• a memory containing computer-readable instructions;
• and
• a computer processor configured to execute the instructions to:
• monitor a charge level of the rechargeable battery of the mobile computing device;
• monitor a charge level of the supplemental battery;
• determine a first charging current level for the mobile computing device and a second charging current level for the supplemental battery based on the charge level of the rechargeable battery of the mobile computing device and based on the charge level of the supplemental battery;
• supply a first charging current at the first charging current level to the mobile computing device through the device interface if the monitored charge level is below a charge level threshold for the mobile computing device;
• and
• supply a second charging current at the second charging current level to the supplemental battery.

A non-transitory computer-readable medium including computer-executable instructions that, when executed by one or more computer processors of a case for an electronic device, direct the one or more computer processors to:

• receive electrical power from an external power source through a power interface of the case;
• receive a communication from the electronic device through a device interface of the case;
• determine a device charging current for a rechargeable battery of the electronic device based on information included in the communication;
• determine a case charging current based on the device charging current;
• supply the device charging current to the electronic device through the device interface;
• supply the case charging current to a battery associated with the case;
• receive a subsequent communication from the electronic device after a period of time;
• and
• adjust the device charging current and the case charging current based on the information from the subsequent communication.