Does anyone have experience with fronting the Pi\LED panels with capacitors? (general power stability question)

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Hi all,

I’m building the cube and while everything is OK I wanted to make sure I’m getting clean power. I’m hoping to power the panels and the Pi (Zero 2) with a single 10000mah battery, largely connected to USB power at the same time. The brightness of the panels will be limited by software so the user couldn’t set all panels to white at 100%, so only really protecting against any spikes in draw. The only real issue I’ve found at this point is the Pi’s USB power for an internal mic seems to want more immediate power, despite the USB power and the battery fully charged connected (I suspect I’ve got some wiring inefficient), and wondered if anyway had similar issues they’ve resolved with capacitors, either bridging the Pi power or the panel power, or both, and at what rating?

Thanks, in general I’m hoping to get some audio-reactive visualisations but want to make sure my wiring is stable so I can move forwards.

kind regards,

Ross

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I’ve seen this problem in general, and basically you have 3 solutions

  1. use a multi output battery pack and dedicate one output to the Pi
  2. use multiple battery packs
  3. use a 12 or 15 or 20V capable battery pack, a USB cable that selects the voltage, outputs more than 5V giving you more watts (up to 100W) and then use a DC-DC converter to get up to 20A at 5V (which is what I do)
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Hi Marc,

Appreciate the response, in the end the solution was to build a proper power path, using a TP5100 charge board, TPS61088 boost board (as the 6000mah lipo is 3.7v), and two ideal diodes where the PSU (5v10A) and boost current enters the main 5v power bus. This way the PSU will provide power if connected and charge the battery, but can run on battery alone (brightness controlled in software), the supply is consistent, and had no drops due to power spikes.

Ross

1 Like
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sounds good. My solution is similar, I just make sure I have 10 to 15A available at 5V and power the Pi directly from the voltage source with its own thick wire to make sure there is no voltage drop.

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Thanks for replying Marc, I appreciate it. It’s good advice, for board to board stuff I’m using 1mm single core wire, then everything else is thick wiring (from PSU and to panels). I’ve added a PWM controlled MOSFET switch for the panel output as I noticed even unlit the 6x panels draw up to something like 0.7A then switch it in software when it lights them. There’s also a voltage divider for the PSU connected check and a MAX17043 board for monitoring the battery levels which makes it fun.

I did try to put a thing on Fiverr to see if someone would design a circuit to include all of the above bits together with the components for 2x active HUB75 connections on a single board with a GPIO header but this would have been tricky (Claude literally told me we have reached the level of being able to programmatically design circuits) not just because if there were mistakes I’d probably not understand them until the prototype boards were built, but eventually I’m going to need to go down that route! :grinning_face: