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Raspberry Pi Zero - portable power source? Beginner's question

sawik123

Hello everyone,

 

First of all (a rather long intro) - I'm not sure if this is the right place to ask a question like this. If it's not, do let me know. It's a very very *very* basic question - mostly because my knowledge of electronics is also very basic. The last time I had anything to do with them was back in college, and even back then I didn't understand a lot about what I was doing. But after watching most of Ben Heck show's episodes, I've decided that I want to build a handheld gaming system using a Raspberry Pi Zero.

 

So anyway - I have most of it kind of figured out. I'll use the Raspberry Pi Zero, I got this screen that takes 5v voltage and connects via HDMI, and I'm planning on using the guts of a SNES controller (since I have tons of these) as an input (it also takes 5v; I'll should be able to use the GPIO on Raspberry Pi and I'll just have to write some driver for it).

 

I'm trying to figure out the best way of powering the whole thing. I'm kind of afraid of using lithium-ion batteries, because I don't want them to accidentally explode or something like that. So I've figured that I'll simply use batteries. And now the question is - does that make any sense?

 

I could use 4x AA battery. That will be 6V with ~2500mAh (I think). I'm estimating that the whole unit will use ~1A. So that should give me ~2.5h of work (which is fine by me, I probably won't use the thing a lot anyway - right now I just want to build it). However, I'm worried about the voltage. It will be 6V, but from what I understand, that drops when the batteries lose charge. I was thinking of using a DC-DC power converter like this one: LM2941CS/NOPB - TEXAS INSTRUMENTS - ADJUSTABLE LDO VOLTAGE REGULATOR, 5V TO 20V, 1A, TO-263-5 | Newark element1. Will that work? Will it be able to take whatever voltage the batteries give out (even if it's as low as 3V) and produce 5V output?

 

Or is there some option better than the batteries, but still fairly safe to use in very unexperienced hands? image

 

Thanks!

Tom

  • 0

    Hi Tom,

     

    One of these types of things could be used, it is pre-built so should be safe:

    http://www.maplin.co.uk/p/lithium-ion-2200mah-portable-power-bank-n49lk

    (That particular one supports up to 1A).

    The LDO you mention would not work, the voltage would drop below 5V as the battery supply dropped below 5V.

    Alternatively this part will provide you with 5V at up to 1.2A, with any input from 4.5V to 9V, which should cover the

    battery terminal voltage as it drops over time, and rechargeable (NiMH for example) cells too (check the datasheet,

    you will probably also need a capacitor or two):

    http://uk.farnell.com/xp-power/jcd0605s05/dc-dc-converter-6w-5v-dip-24/dp/2065280

    E-bay has some cheap DC-DC converters but they could be more trouble than they are worth.

    Overall I think the 'USB power bank' type thing could be the most cost-effective way all-round.

     

    Basically, just take sensible precautions, like avoiding non-reputable sources for DC-DC converters, batteries

    and even wire. Personally I would never buy a battery from ebay for instance, because as you say there is a

    high risk of bad things happening. Make sure your wiring is tidy and secure, check for short circuits with a

    multimeter before attaching the battery.

     

    Do show your project! : )

  • 0

    SNS-002: for use with the

    SUPER NINTENDO ENTERTAINMENT SYSTEM

     

    INPUT: 120V 60Hz 17W

    OUTPUT: 10V - 850 Amp

    How which do i need NINTENDO AC Power Supply cable NES-002 SNS-002 NUS-002 DOL-001

     

    Duracell AA Rechargeable Batteries 2400mAh Long Life Ion Core (4-Batteries)

    would fit your plan. But look at above 10V at 1.3A goes to SNES system.  But the 1A current is not enough budget for zero/snes/screen. You need give details of screen like maker & model.

    Clem

  • 0 in reply to shabaz

    Huh, a power bank - haven't thought of that, but it does seem like a pretty obvious choice. I'll look into that, thanks for the idea.

    I will show my project, once there is something to show image

  • 0 in reply to shabaz

    Definately a power bank if you are new to electronics it simplifies the whole power management and charging whilst been relatively cheap and effective with a good power density.

    Other  solutions require a lot more hassle to do right and obviously a very un happy owner when  they are done wrong... Good luck with your project.