US Patent 7816057 Fuel supply method for direct methanol fuel cell

In a direct methanol fuel cell, fuel efficiency is maintained by periodically adding a higher methanol concentration mixture through a cartridge into the primary fuel container. The cartridge replenishes methanol and partial water losses due to the consumption of fuel in the power generating process. In a typical system, the fuel replenishment mechanism is controlled through an electronic apparatus that monitors the power conversion process and is capable of predicting remaining operating capacity.