For the prototype we have used an inexpensive(15$) Oneplus 10000mAh 2A USB powerbank to power the power hogging warmer system.

The recent Samsung Galaxy Note 7 explosions brought to light the fundamental flaws in Lion/LiPo chemistries and thus we decide to move away from it in the future.

A 6.4 V, 10000 mAh Lithium Iron Phosphate battery pack is to be in the upcoming revisions of our system. LiFePo4 chemistries are very safe and are unlikely to explode thus making us choose it over LiPo.

For powering the heating element at 7V we use a MT3608 boost convertor to get a stable 7V from the 5V input.

The net current consumption (Including sensor&MCU power) was about 550mAh with the heater on and total power consumption was a 2.75W.

Due to the lack of electricity in rural areas, We aim to make the battery packs hot swappable with solar charging system for charging the batteries individually.