Hi I am very new to electronics and Arduino but I am loving the experience thus far! I was hoping someone would be so kind as to clarify a few things for me.
I used to just run my projects from my pc USB, now however I want to run my project from a 3.7v LiPo battery. I thought this would be very basic but after some research I am not so sure anymore. I also have a couple of breakout boards and motors i want to connect to the Arduino. These are listed below.
Motor Driver 1A Dual TB6612FNG
2x 3.3v dc motor
Sparkfun Bluetooth Mate Gold
USB LiPoly Charger
LiPo Fuel Gauge
First question
Is the voltage of the 3.7v LiPo enough to power a Ardunio Uno R3. If not will I need to get a step-up boost module or is there another alternative?
Second question
All of the above components seem to work with a voltage of around 3.3V. The output pins on the arduino outputs 5v if I am not mistaken? How could i get these to output around 3.3v instead of 5v? Could I use a voltage divider (new concept to me) to reduce the 5v to 3.3v going to a specific component?
Sorry for my lack of knowledge on the topic of electronics and Arduino. Any help and explanation of concepts relating to the above would be greatly appreciated.
A Lipo will be about 4V fully charged and fully discharged around 2.5V so you really do need a boost converter to convert to 5V. You can then use a 3.3V linear regulator if you don't need much current at 3.3V in order to convert the 5V back down to 3.3V.
A Lipo charger and motor driver should pretty high current things. A good 2A boost converter should be capable of supplying the arduino and motor driver.
It does seem a bit odd that you are using a lipo to power a separate lipo charger though. You won't get good efficiency charging one lipo from another.
Hi thanks for the assistance. I will read up a bit about linear regulators.
Sorry if there was any confusion regarding the charging. How i though of rigging it all together was, the LiPo battery connects to the fuel gauge module. The fuel guage then connects to the charging module so I can charge the battery with a micro-b cable (or whichever connector it has). I was then going to connect the charging module sys out to the arduino.
Here is a link that demonstrates it Uh-Oh Battery Level Indicator Hookup Guide - SparkFun Learn
Would this be feasible? Also judging from you previous answer I take it I would need to connect the charging module to the boost converter and then go from the converter to the arduino to get the needed 5v?
What battery were you planning to use?
Some have built in battery protection circuits.
My personal approach would be to use a TP4056 based charger and get one with built in battery protection to protect against over discharging, high discharge currents and over charging. Something like :-
www.ebay.co.uk/itm/5pcs-TP4056-with-Battery-protection-LIPO-Charger-Module-Board-Micro-USB-TE420-/301905672102
You can then use cheap 18650 cells which don't have protection but very good capacity for the cost. Beware of ones off ebay though as vast majority are fakes with poor capacity.
These are an easy way for the Ardiuno to measure the battery state:-
I have used this to convert LIPO voltage to 5V at a decent current
http://www.ebay.co.uk/itm/152080552199
But your suggestion would work just as well. My comments above are just based on the modules I have played with.
Great man thanks so much for the info. Ever bit adds another piece to the puzzle that is my growing knowledge on the topic =]
Currently I have a tendency to go for the sparkfun products as it feels like they are pretty widely used and well documented. They seem however to be substantially more expensive so those components you suggested may be more viable alternatives.
Thanks again for the assistance!