I'd like to find a power bank circuit with 2.7V input

[emtae55]

TL;DR

I'd like to buy a power bank circuit board which input voltage with 2.7V. 'Cause I'll make power bank with super capacitor.

Hey, can you find me a power bank circuit which has 2.7V input?? Because I'm in a project which makes power bank with super capacitor, and you knows that we can't input voltage above the maximum voltage of capacitor, right?

You can refer this video.
Thanks.

 

[Rive]

Maybe there is such thing, but I suggest you consider something first: the circuit will work only in a range. So, maybe between 2.2 to 2.7V => around half (or more) of the energy will remain in the capacitors, inaccessible.

You can make it better by using two capacitors in series instead of sticking to the 2.7V.

 

[emtae55]

Maybe there is such thing, but I suggest you consider something first: the circuit will work only in a range. So, maybe between 2.2 to 2.7V => around half (or more) of the energy will remain in the capacitors, inaccessible.

You can make it better by using two capacitors in series instead of sticking to the 2.7V.

Thanks. And can i ask you something else??
If i make a power bank with capacitor, should i use a protection circuit?? Because I can't find protection circuit for capacitor. There were only protection circuit for Li-ion Battery.

 

[Rive]

Depends on how deep do you want to dig into the topic. For limited capacity DIY project protection circuit is optional, not necessary: you can start without it.
But you have to keep in mind that supercapacitors are very different from batteries, so you have to be very careful with the charge/discharge circuitry.

Honestly, this size/application is not really part of the economical usage of supercaps. Still, it qualifies as a DIY project.

 

[berkeman]

Hey, can you find me a power bank circuit which has 2.7V input?? Because I'm in a project which makes power bank with super capacitor, and you knows that we can't input voltage above the maximum voltage of capacitor, right?

As you start to learn about battery-powered circuits and using supercaps for energy storage, it is good for you to learn about how to efficiently manage voltage conversion for such circuits using DC-DC converters.

As @Rive mentions, if you can only use a small range of the output voltage of a battery or supercap, you will likely not be able to use most of the stored energy before recharging is required. If you try to make a 5V power supply from `1.5V batteries, it is hard to come up with a configuration of them that will efficiently get you to 5V when using a low dropout linear regulator. Instead, it's better to use 2 of the 1.5V batteries in series, and follow that with a DC-DC "boost" converter to boost up the ~3V up to 5V and keep it regulated. Using such a circuit you can get 90% or more of the energy out of the batteries before they have to be recharged. Similarly for supercap-based circuits.

https://en.wikipedia.org/wiki/DC-to-DC_converter

Also, you can use a DC-DC converter topology called "buck-boost" to let the input voltage from your batteries or supercap start above the output voltage, and droop below it as they discharge. You might do this when using 2 x 1.5V batteries in series to make a 3.3V power supply, for example.

https://en.wikipedia.org/wiki/Buck–boost_converter