Charging/Discharging circuit for multiple 18650 batteries

Thread Starter


Joined Oct 5, 2016
Hi all,

Basic information:
I am planning to power up Raspberry PI3 with 3 or 4 Latium iron (18650) batteries (batteries will be connected as parallel mode) which will have 3.7v and 3800maA in each cell. To turn on a PI, you need to provide 5v and 1A current.

What I need:
I realize that, I need to have a step-up convertor to change the voltage from 3.7 to 5v. This can be done using a step-up or a buck convertor. Can someone suggest me a circuitry design for this or perhaps a good step-up convertor module, where I can purchase from eBay or Amazon.

I also need a battery charging indicator (2 or 3 LED bulb will be sufficient) circuit to indicate the battery level, along with auto discharging circuit. I also need a way to figure out if the voltage drops below 3v, the Raspberry Pi should turned off. This can be done using GPIO pins of PI but I need to know how to find out whether the voltage has been dropped below 3volts.

Can someone help me on this please?

Thanks in advance.
Good day