Embodiments of negative pressure wound therapy devices, systems and methods are disclosed. In some embodiments, a negative pressure wound therapy device includes a negative pressure source configured to provide negative pressure to a wound via a fluid flow path, a power source configured to power the negative pressure source, and a charging circuit configured to monitor a temperature of the power source and charge the power source. The charging circuit can be further configured to in response to a determination that the temperature of the power source is below a temperature threshold, provide a first charging power to the power source. The charging circuit can be further configured to in response to a determination that the temperature of the power source has reached or is above the temperature threshold, lower the first charging power to a second charging power.