Hi,
I have a rocket application, where light weight is of importance. Assuming I have a 3.7v 400mAh Lithium ION battery, I am trying to find out how I can best connect it to a Raspberry PI Zero W (https://www.sparkfun.com/products/14277). I don’t need the USB ports for the application. Should I use charger/ booster (https://www.sparkfun.com/products/14411) to boost from 3.7v to 5v and connect it to the micro-USB power port? Can the micro-USB power port run on 3.7v, or does it need 5v?
Alternatively, can I directly connect the battery to the 3.3v terminal and ground?
Thanks,
Mike
Hi Mike.
The Pi needs 5 volts and 3.3 volts to work so you’re going to need to generate a 5 volt supply that can deliver 2.5A worth of current. Unfortunately SparkFun doesn’t carry a boost regulator that could turn 3.7 volts into the 5 volts your Pi is needing. We haven’t tested it, [but something like this might do the job. Chances are you’re going to need a larger battery than 400mAh though since the boost regulator is going to demand quite a bit of current from your 3.7 volt battery to make 5 volts at 2.5A.](Pololu - 5V Step-Up Voltage Regulator U3V70F5)
I am able to run my RPi Zero W from a Li ion battery (no boost)… functionally all the way down to 3.3V. Everything except for USB runs off the 3.3V buck regulated rail (from the 5V input). You can even run wifi and bluetooth below 5.0V.
Make sure you disable HDMI and other things to save as much power as you can. I run at 100mA @4.0V
https://www.jeffgeerling.com/blogs/jeff … rve-energy
Thanks for the advice. I am currently using the SparkFun battery: https://www.sparkfun.com/products/14367, but they are somewhat heavy for my rocket application, where weight is a consideration. The nice thing about these batteries, is they indicate a % of power left, which helps in preventing the PI from having a hard shut-down. I have a few 3.7v batteries that I will try, as the application only requires about 10-15 minutes of operating time, and the 3.7v batteries are considerably less weight.