LiPo safety - short title

Hey guys, hope all is cool with you folks.
I want to use the batteries in the link below for a small form project using the Arduino Pro-mini.

As you can see the batteries are 3.7 V each and obviously won't power up a ProMini.

Is it okay to put these LiPo batteries in series and get 7.4V?

I ask this because I am concerned that there might be some voltage imbalance of some sort ( or other unknown electrical variable) that might start a fire. I heard LiPos are pretty moody.

( I know this is not an Arduino related question, but I hear how LiPos are easy to catch fire if you do the wrong thing with them. In consideration for safety, I am asking this question )

Thanks for the replies!!!

Yes.. But why don't you just buy a 2S lipo? Something like this?

It will if you use a 3.3V Pro Mini. Also many other Arduinos that run on 3.3V.


Charge them individually, and watch them over their life to see if either starts to discharge and charge differently to the other.

Replace cells that can’t keep up.

And all the other precautions you are running into.

Tip: spare a pin on the microprocessor to measure the battery voltage and alarm or take action if you discharge below, say, 3.3 volts per cell under load.

That they really don’t like…

Also watch that cheap charger and flunk it if it ever goes over 4.2 volts per cell, or be there to remove cells when it is about to.

AND if you do god with 7.4 volts, and a 5 volt Arduino, consider using a buck regulator to give you the 5 volts, your battery will last longer if you get a decent one. See

and go conservative on the specs, test with the load you expect.


Too big for my project.

I bought a " IZOKEE Redesign Pro Mini ATMEGA328P 3.3V 8MHz Module Development Board Microcontroller for Arduino (3X 3.3V 8MHz)"

So it seems like it should work with the 3.7 LiPo battery I got. ( I thought that the 3.3 V was referring to the logic level or something)

( A spark fun datasheet said that these have built in regulators; so i wont worry about the need to solder a regulator )

Hey ty for the reply. from what aarg said above, it looks like my Pro-Mini will work with one 3.7LiPo cause my ProMini runs on 3.3V. Ty again for the reply!

Another option is to use a step-up power supply to deliver 5v.

Ty for the reply. The size of the entire project might not be able to accomodate a power supply.

Do yourself a favor.
Compare stepUP
And stepDOWN

Either way you will be using one.
Or using a different battery that outputs the voltage you need.

Hi @Mars-Sojourner

What is your project?
Why small profile?

Thanks.. Tom.. :smiley: :+1: :coffee: :australia:

That project incorrectly runs the Nano on 3.7V. It's out of spec, but the maker probably found that it worked and plowed on... but you could do it safely with a 3.3V Pro Mini.