I started making a "case-top" as I like to call it. Raspberry pi 3-based laptop. Took an electrician's case emptied it and started putting the components in.

https://www.sparkfun.com/products/12711 connected to 4 18650 3400mah protected batteries which are in parallel, and each one has a TP-4056 JUST to avoid explosions. An XL6009 takes the power from the charger and drops it on the pi @ 5V, and another XL6009 takes the the power from the charger and drops it on the LCD CONTROLLER @ 12V.

The afformentioned board is similar to this http://www.ebay.com/itm/NJYTouch-M-NT68676-2A-HDMI-DVI-VGA-AUDIO-LCD-Controller-Board-for-LTN170X2-L0-/282420095187.

When I use the 12V 4A it requires instead of the batteries it works perfectly. Power, sound, light. The screen works like a treat. But when I try to power it from the batteries, one small LED on the button board flashes once and I get nothing. No power, no light, no nothing.

I know the XL6009 WORKS, because I did measure the out volts and i do get 12.1V constant on the plug, not on the board. So both the board and the cable/plug I have soldered have power.

What am I missing, (apart from a brain)?

enter image description here please notify me if it is not readable. Thank you😊

The batteries are these http://www.keeppower.com.cn/products_detail.php?id=375

and these are the step up modules http://www.gearbest.com/other-accessories/pp_227265.html

  • 3
    \$\begingroup\$ Your brain is great and if you could use it to get your hands to draw a schematic, it'd reach genius :-) Please draw one, the schematic tool's a doddle to use. \$\endgroup\$ – TonyM Apr 9 '17 at 22:27
  • \$\begingroup\$ Did you measure it under load? A scope would be great help here. \$\endgroup\$ – Passerby Apr 9 '17 at 23:04
  • \$\begingroup\$ @TonyM up untill a month ago i had not touched a soldering iron ever i am not an electrician i have not gone to any classes or been taught by anyone about electronics. Just one day someone told me abot Pis and i looked into it. Had a busted laptop and thought hey. Make a new one with the pi. Can't be that hard. Well it is apparently so i can't draw you a schematic cause i don't know how to. Yet. I am not of much help cause i do know you need these things to give me a helpful answer but unfortunately i have to learn it myself first lol \$\endgroup\$ – N.Graps Apr 9 '17 at 23:30
  • \$\begingroup\$ @Passerby I would love to but i don't have access to an osciloscope or to a lab/desk regulated power supply. Only thing i have is a multi-meter :/ And hopes and dreams and a few 18650 batteries. And eventually i will end up blowing something up hahaha \$\endgroup\$ – N.Graps Apr 9 '17 at 23:32
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    \$\begingroup\$ I understand. I'm sure you can hand-draw a diagram of what you describe and post that, though. You can scan it or use a mobile phone camera to do so. Without it, we can't go any further, I'm afraid. \$\endgroup\$ – TonyM Apr 10 '17 at 5:39

Pretty elementary: your boost converter (Datasheet: http://www.sunrom.com/get/283300) can't supply enough power (not even close).

The IC is rated at 4A absolute maximum input current. At depletion your Li-Ion cells will be around 3v. 3V*4A = 12W (theoretical). Even at 100% efficiency this equates to just 1A of available current at 12V, so you need to juice your power delivery capability by 300% (and then again my another 20% over that (minimum) since you can't run PS components at redline and expect things not to mushroom cloud.

My advice ?

Ditch the 1S4P battery design, get one of those cheap car starters off Amazon that include MicroUSB charging. Use the 3S LiPo battery, inside it and add your 3Ah cells to it (having one left over) for a 3S2P config and ditch the boost converters entirely, using the 2A USB buck converter in the pack for the RPi and run the peripheral board direct from the cells.


Have fun on your journey to realizing just how cheap laptops are ! ;)


  • \$\begingroup\$ Thank you very much sir. You have been a lifesaver. I am sure it is elementary to you but I was not familiar to watts amps and so on up until a bit of time ago. Thank you very much. I will surely try it. Again, a big thank you😊 \$\endgroup\$ – N.Graps Apr 15 '17 at 12:13
  • \$\begingroup\$ It says I have less than 15 reputation every time I push the vote button. It says it's not counted but it is recorded😠 \$\endgroup\$ – N.Graps Apr 17 '17 at 18:17
  • \$\begingroup\$ You think if I go with something more expensive like this: amazon.com/gp/aw/d/B00ZZGE4LU/… I can forego opening the power bank and use the batteries and other components in another project? Is the 5 volt 2.1 amps port going to be sufficient for the raspberry pi 3 b with minimal peripherals? \$\endgroup\$ – N.Graps Apr 17 '17 at 19:32

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