Actions
Forum Thread Details
  • Replies 2 replies
  • Subscribers 30 subscribers
  • Views 351 views
  • Users 0 members are here
Related

Portable Pi - Battery Questions

bikr

Ok.

 

So I've begun slamming through my portable pi / mame build.  So far it's going amazingly well.

 

I've got all of my parts 3D printed and my pi slimmed down. 

 

I have my analog stick in place and working on button arrays as well.

 

I've split my battery to change the orientation and that's when I started to get curious.  I may have missed it in the trillion times I've watched the videos, but how and what do I wire up my batteries to?  I am using the same exact setup and parts as Ben did, but I'm left with a red and black lead (+ and -)  and if I wire them into the screen then I can't charge.  Do I need a charging board that will allow load / batt etc?

 

If so, which board did Ben use?  Or did he build one himself?  Based on the system he setup, is there an off the shelf that will work?  I'm thining the wiring will go like this:

 

 

Barrel Connector ----->  Chargerboard Input 

Battery leads ----> Chargerboard Batt

Chargeboard Load ---> LCD

 

5V tap on LCD ---> Raspi

 

 

All else is going great, so if someone can clue me in there that'd be amazing.  image 

 

Oh and here's a shot of my progress so far:

 

image

 

--Josh

  • I believe those batteries had their own protection circuit, though I could be wrong, if they did, he re-used it.  If they didn't, I doubt he added his own and probably just went in series with them.

     

    As for charging, he's using a universal battery charger by Tenergy, like this one

    http://www.amazon.com/TLP-2000-Tenergy-Universal-Charger-3-7V-14-8V/dp/B001BEXDRQ/ref=sr_1_5?ie=UTF8&qid=1378945302&sr=8-5&keywords=universal+charger+tenergy

     

    It doesn't load balance, so its not the best, I think the board the battery connects to maybe alleviates that some.

     

    Our next rev I'm thinking of putting the batteries in parallel and having separate boost convertors for the Pi and for the screen, with the screen one having multiple voltage outputs for possibly different screens.  Also I plan on having an onboard charger so you can just hook up either a barrel jack or a usb cable to charge the device (from a wall wart or something that can sustain 750mAh or so of current).  Unfortunately I'm a busy guy and haven't gotten around to working much on this project with him.

  • in reply to colecago

    Related question. I apologize if I should have turned this into its own thread.

     

    I've done a few portable console, computer mods in the past but I've always relied on premade battery packs (tekkeons, energizers, etc.) to provide power. I'm in the process of making my own portable Pi and I've watched the video a ton of times. I'd like to use similar batteries to the one's he's using (they do come with the recharge circuit and overload protection.) What I'm having trouble with is understanding what's going on with the DC barrel jack.

     

    If I were wiring the barrel connector in a typical fashion (no batteries), I'd be attaching the ground from the Pi to the barrel shell pin and power from the Pi to the center pin. The switching pin also goes to ground. Once you plug in a DC plug (connected to a power source, wall wart etc.), positive from the plug goes to the Pi via the center pin connection. But what Ben's done is hook up power from the batteries to the shell pin and power from the Pi to the disconnect pin, so that when something is plugged into the barrel the Pi disconnects.

     

    What I don't get is: am I connecting ground coming from the Pi to the center pin? and what about ground from the batteries, also to the center pin? Plus the DC plug connector coming from the battery charger, normally inside the connector is + and outside is -, should this be reversed as well?