A user device can include a first battery configured to power the user device and a second battery configured to power the user device. The user device can further include a temperature sensor configured to monitor a temperature of the second battery and a heating element configured to heat the second battery to increase an operating efficiency of the second battery when a temperature of the user device falls below a threshold temperature value. A switch can be configured to switch on the heating element to heat the second battery when the temperature sensor determines that the second battery is below a threshold temperature value.