# Supercapacitor To Lithium Battery Converter

Published February 14, 2022

# Comparison

Crudely, the efficiency cuts down the capacity by 75%, and it only works (for smartphones, depends on current load) down to around 1.25V. At peak, the supercap is 2.85V, so we can use 1.25^2/2.85^2 = 80.7% of the power in the cap. This means when we calculate the equivalent lipo capacity of a supercap, we need to downrate it to 60% of total capacity. Ouch!

Could another boost converter be better? Well, the 80% downgrade is inherent to the supercapacitor at certain current output needs, and I don't think many boards can boost and output >0.5A below 1.25V. I did see one more TI part which was out of stock for two years though, and it can do a bit higher current. The 75% efficiency can be better, but not at high current draws, and is capped at 90%. A realistically perfect converter would yield around 90%x90% = 80% of the supercapacitor power, which is a lot more than this board's 60%. However, this converter board works pretty well, and it's not like supercapacitors don't already have a supply issue already.

# Conclusion

One day I will get my hands on that TPS chip, but until next time, cya!