The most popular battery voltage for lithium and lipo batteries used in battery packs for microprocessors and electronics projects is 3,7 volts. Microprocessors usually operate at 5 volts. Popular electronics often operate at 12 volts or higher. If you are now asking yourself something like: “Then how can I with a 3.7v battery, steer a 12v Car light with a 5V microprocessor all in the same circuit?” – then this guide is for you! In just 5 minutes you will be able to accomplish this. In this short guide I will teach you about step ups (also known as boost modules or adjustable power converters) , what you need to know about them, how to hook them up and which one you should choose for your project. Step ups are a great choice because you can buy them for as little as 0,50 USD if you know where to look!
Step 1: The Problem: You Are Trying to Power Something That Requires a Higher Voltage Than Your Power Supply / Battery Can Supply
Example: You have an arduino uno and want to make a 12v automatic off the grid garden light. You are powering it with lithium 3,7 volt batteries (because that is almost always the best way – I will make a battery guide soon). You could use 3 X 3,7V lithium batteries in series to power it but that would be to little voltage and expensive as batteries are often the most pricy part of your circuit. 4 X 3,7V would fry your circuit. BAD CHOICE!
Step 2: The Solution: Using a Step Up Module / Booster Module
You will find many complicated books, sites, diagrams and instructables trying to explain you how to step up voltage. The physics behind stepping up voltages are quite advanced. Some guides will encourage you to wind copper coils yourself and build large contraptions. Do not put yourself through this! This is 2016! Since 2015 small inexpensive circuit boards called “step ups” have become widely available from China in quantities of 1. A step up is a circuit board that takes your input voltage and multiplies it by a factor you choose by dialing a button (called a potentiometer and seen in the top right of the pic above). Seriously that simple? Yup! It can’t be? It is!
The most efficient solution for the problem we described in the previous step: You connect your single 3,7V
battery to a step up board. Step it up to 12v. The arduino uno as well as most other micro proceesors can accept 12v as input and the same input can power your 12v light bulb. You use a mosfet or voltage regulator on the arduino’s pins between the battery and the 12v light bulb to be able to control it with the arduino’s 5v I/O signal. See diagram above, the multimeter replaces the light bulb here.
So why are step ups so great? Because they are dirt cheap and precise! For less than a dollar you can regulate the voltage in your circuit to 100Mv simply by turning a screw clockwise for more and counter clockwise for less.
Step 3: What Is This Witchcraft? Which Step Up Module Would I Need? Where to Best Buy.
So now you know you need a step up in your circuit. But which one? There are four main types (pictures are above). Cheap low amperage modules with or without usb, step ups with voltmeter displays on them and finally high watt / amperage modules.
1) It is not magic that makes the voltage higher but current. If you multiply the voltage by a factor of “X” you will also drain “X” times more current from your power supply.
Example: If you have a 4V battery as input and want to power a 12V light bulb that uses 500ma at 12V, than the battery will need to deliver 4V and 1500 ma to the step up for it to achieve12V, 500 ma ( notice the input voltage is multiplied by factor 3 but the current is divided by 3).
2) Respect the current rating on your step up. Every step up comes with a max current input. This is often what causes the price differences between units.On the otherhand, do not go overkill because the step up in itself drains a bit of current.
3) Respect the minimum voltage: every step up has a minimum input voltage. If you put in less, it will not work properly. If you have a battery of 3,7V, the step up needs to function with an input below 3,7V as the voltage will drop a bit during depletion.
4) Units with a voltmeter are larger and more expensive. Only get one for prototypes.Personally I also experienced them to be more fragile.
5) Buy from China! This rule applies to most electronics.Step up boards are only available from www.aliexpress.com Some people on amazon and ebay buy them there and sell them at 5 times the price. Don't fall for it. Good low watt modules like the mt3608 start from 0,50 USD.
6) If you for example want to power an arduino uno and a 48V motor with the same 3,7v battery the solution is just as simple: Use two step ups, one for the arduino and one for the motor.
Step 4: How to Use Your Step Up Module
If you found the right step up module, hooking it up is super simple:
1) connect the battery or DC power supply plus and minus cables to their respective connectors on the "IN" side clearly marked on your step up.
2) Connect a multimeter on the "OUT" side of your step up. Connect plus to plus and minus to minus
3) Screw the dial shown in picture above untill your multimeter displays the desired voltage
4) replace your multimeter by whatever you wish to power.
Any comments, remarks and questions are welcome. I will answer! I am entering this instructable in some contests so if you liked it, please help me win by voting on this and my other "super noob friendly instructables" (more to come every day). Every vote means a lot! ;)