ArcherBoy27
Posts: 91
Joined: Thu Sep 29, 2016 10:36 am

Battery Powered PI

Fri Nov 11, 2016 3:28 pm

Hi guys,

I am looking into battery power for my raspberry pi 3 with the official touch screen and to power it i need an output of 5V and at least 2A. I have found many batteries that would be fine however they only output 3.7V. I know I can use a DC/DC converter to boost it however i then i don't get 2A. does anyone know a way i can get my required output?

Thanks in advance
There are 10 types of people in the world: those who get binary, and those who don't

ZedaZ80
Posts: 4
Joined: Wed Sep 28, 2016 10:04 pm

Re: Battery Powered PI

Wed Nov 16, 2016 12:56 am

I'm sorry, I don't have an answer, just a related question and I didn't want to start a new thread. Hopefully we can both get an answer :P

I have the battery, is there an easy premade circuit that can charge it and boost output to 5v, 2+A and make sure the battery doesn't dip too low and explode?

I got my hands on a lipo battery 8000mAh 3.7v. I've read a bunch of posts and articles on how to power a pi with it, but I'm honestly not experienced enough to know exactly what to do. I would actually like to make a portable battery pack to charge my phone as well as be able to power my pi. A while ago I bought a battery pack with something like 5v 12A output, but the Pi would turn on, then flicker off after a second or two (I think it was drawing too much).

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mikronauts
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Re: Battery Powered PI

Wed Nov 16, 2016 1:07 am

Make sure you get a DC-DC step-up converter that can output 2A+

2A 5V output will need a battery that can supply approximately:

(2A / 0.85) * 5V/3.7V = 3.18A @ 3.7V

The .85 is a good value to use for the efficiency of the step up converter.
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Advanced Robotics, I/O expansion and prototyping boards for the Raspberry Pi

Rabbit_Pi
Posts: 23
Joined: Fri Sep 23, 2016 3:03 am

Re: Battery Powered PI

Sat Dec 17, 2016 9:45 pm

Ada Fruit sells a 3.7v to 5v powerboot for such projects. You can use the 1000C model.

Project Overview: https://learn.adafruit.com/7-portable-r ... t/overview
Wiring Diagram: https://learn.adafruit.com/7-portable-r ... it-diagram

The files to take to a 3d printer for the case can also be found there. Note that you can upgrade to a higher aH battery as long as it is within the 3.7v range with this board. Mine was $28 US dollars off amazon.

Also some useful Info:
when dealing with batterys and runtime, aH(amp Hour) is used.
the rating means if the battery is rated at 2aH, than a device pulling 1 amp will run for 2 hours.
the scale of ma and maH is this. 1000ma = 1A (ma milliAmp)
so a battery(like listed on the links) that is 3.7v and 2500maH, translates into 2.5aH.

The Pi 3, disregarding the usb ports, the quad core at idol usually is around 250ma and at peak between 700-800ma. the hdmi port pulls about 200ma, bluetooth and wifi(if i remember double check this) between 60-120 ma range. Hence at peak proformance, + bluetooth +wifi +all four USB +hdmi the power consumption is a little over 2amps(2000ma) hence the reason for the 2.5amp(2500mA) requirement for power source. at 2 amps being pulled, the pi produces 10 watts of heat.

Also remember, in DC your Volts is your constant and your amps alter, where in AC your Volts alter and your amps are the constant. (AC 110 is the bottom of the wave and 120 is the top, U.S. at 60hertz(how many times the volts bounces between 110 to 120 per second)

Rabbit_Pi
Posts: 23
Joined: Fri Sep 23, 2016 3:03 am

Re: Battery Powered PI

Sat Dec 17, 2016 9:59 pm

One last input:

In the Electrical trade and field, everything is rated to carry 65% or 80% of your required load. Instance, when wiring a house, how many devices (light fixtures and receptacles) we add to that breaker is measured to ensure that in normal use 65% of the total amp compasity of the breaker is used, and at max draw only 80% is used. for instance, on a 20 amp breaker, we make sure that all devices cannot pull over 16 amps. (this varies on how many appliances are plugged in and power strips etc.) Therefore, on your battery compasity to get a optimal runtime, I suggest adding 65% or 80% of max load to your maH.

hblanken
Posts: 10
Joined: Fri May 06, 2016 11:43 am

Re: Battery Powered PI

Thu Dec 22, 2016 10:16 am

Would this work with a Pi? I am also looking for a batter powered Pi solution.
What adjustments to this UPS3 would you all recommend (if any?) to make this board work with a Pi?

ODROID-UPS3
http://odroid.com/dokuwiki/doku.php?id=en:odroid-ups3

Lonewolff
Posts: 144
Joined: Fri Dec 28, 2012 11:13 pm

Re: Battery Powered PI

Sat Dec 24, 2016 8:20 am

You could use any 'off the shelf' power bank (the same ones used to charge up iPhones etc on the fly).

That's what I currently use and they are as cheap as $10 these days.
Loving my peice of the Pi

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exartemarte
Posts: 373
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Re: Battery Powered PI

Sat Dec 31, 2016 4:07 am

Li-Po batteries are potentially dangerous and I would strongly advise against a DIY approach unless you are sure you know what you are doing (in which case you probably wouldn't be asking for advice here). As well as a suitable boost regulator you would need safe wiring, a Li-Po battery charger and some system for monitoring the battery voltage so that it doesn't discharge to a level that would damage it.

All that is taken care of for you if you adopt the powerbank solution. Powerbanks have charging circuitry and 5V regulators built in. They come in a variety of sizes/Ah ratings: the smaller ones often have only a 1A output but the larger ones generally have both 1A and 2.1A outputs, and the latter should be adequate for the system described in the original post. The greater the Ah or mAh rating the longer the battery will last before it needs recharging. Powerbanks can be charged from any 5V source such as a wall wart, phone charger or even a USB port (but don't hold your breath ...); some have built-in switches, and LEDs to show the state of charge. The only downside I'm aware of is there is no way, other than the aforementioned LEDs, of knowing how much charge is left in the battery. When it gets too low the regulator will switch the output off, but while it's running the output is a steady, regulated 5V.

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