Marc's Public Blog - Electronics Hacking

And if you want even more details and history >>> See this full article on the why and evolution of my LED outfit <<<

Prototype of new version:

The previous v6 was an attempt at simplyfying v5 by integrating the batteries directly to the back of the panels. In the case of Lipo batteries that I cannot let run flat or they'll be damaged forever, and need for extra wiring for the balance connector, it was simpler to attach everything to the back of the panels, but it made the panels quite heavy and more bulky looking.
That outfit served me well, but outside of bulk and weight, one issue was getting the lipo batteries through airports. They are totally legal and allowed, but they had to be removed from the outfit every time I flew, which was a pain in unwiring/re-wiring, but even then, I would get stopped more than half the time I went through Xray while they got a supervisor to confirm that yes indeed the batteries were fine. A few times, I got less educated people who reacted in lesser ways, and called more people, a few times causing delays of 30mn or more. To be more specific:

The batteries are in green below, they showed up pretty reliably on Xrays and the whole thing would get flagged and then they would have to look at them and the wires, and often were not super happy:

So, I ended up making a removable battery pack that was wired correctly, and putting it the right way was tricky, so set it up to be correct and in one piece that could be removed and re-added with less work for each flight:

But it didn't take long to find out that even carrying the batteries separately that way still made TSA unhappy at times, and unless I unplugged absolutely everything and rebuild the whole thing every time, they would not be very happy and that was a pain for me to take apart and rebuild every single time. They still occasionally said it looked like C-4.

I wasn't being a contratrian for fun, and see how many world TSAs I could win an argument with, I just didn't really have many other options, I did need those big batteries because my outfit does need lots of power, and 5V USB battery packs simply do not output enough amps.

tried with USB packs

it was not fun, I had to segment power use in different busses plugged into different ports of battery packs, very cumbersome and the first tone to die could shut down everything

But after multiple years (and to be fair, it was many flights and most were fine, but the 5-10% that were not, were _not_ fun), technology finally evolved into whas that gave me better options: using less scary looking USB powerbanks that were finally able to output enough watts to power my panels without dipping power enough to cause reboots and crashes from the CPUs.

so I built a new system with dual 20V input (each one is sufficient on its own)

I have 2 USB-PD selector boards that output into a diode to avoid backfeed, and this goes into a DC-DC converter that takes the 20V down to 5V at up to 20A although probably only 5A max is really needed

It of course runs fine from a single battery:

At the same time, I made a big upgrade on the panel side by using flexible PCB panels that are differnetly thinner. At the same time I switched to RPI0 2W which is slightly more powerful than an RPI3a while being much smaller:

Now the whole thing looks nicer and lighter:

I did switch the big ESP32 to a smaller smaller ESP32 C3 (2 shown in this picture), which can still output to an LED strip if I really want/need. I also tried to switch to a smaller electrodragon passive-3 board that was custom designed to fit the RPI0 2W. It doesn't have the room for the level shifters, but turns out for an ABCDE panel, the passive board worked just as well (top on the picture vs the bigger red one in the middle):

The old setup had 300Wh of battery capacity, and that was real capacity, no BS. I measured it to give me a bit over 18H of runtime, which was very nice indeed, and helpful for places like tomorrowland where I had to camp and go 3 nights without ability to recharge.

This new setup differs a good amount because:

Same on youtube:

But of course, nothing can be simple, this new design brought some new issues:

After using it the first time at ASOT NL 2025 the wooden frame got detached in no time, failure of the 2.5mm screws

very early version without clips on both sides

just a bit of tape to hold things together, clips on sides and top

it was built until the flight and I didn't have time to add a protective frame

the panels were so cheaply made that the screws receptacles came unglued

Another issue I didn't like with these ABCDE panels is that the screws were 2.5mm instead of 3mm for unknown reasons and it was hard to attach to something that small.

Switching to a different 128x64 P2 Flex Panel vendor, but ending up with ABC panels that barely worked with rpi-rgb-panel

Sadly those ABC panels had different chips that required huge gpio slowdowns or suffered from noise and display issues:

new chips

It took a few weeks, and very kind help from board707 and multiple issues to make a new line addressing shift register pusher that was faster and didn't have the noise/corruption issue:

once I figured all that out, finally got the ABC panels to work almost as fast as ABCDE and now have a nice screet/pixel protector

USB powerbank failures

It took some tracking down to catch real time failures:

Flexible PCB solder point failures

flexing the PCB can cause any of those points to fail, causing the above

and they fail in different ways :(

Oh no, it looks terrible when it fails in the wrong place

Easier Replacing of Panels

This is not a great long term solution, but I have no better idea for now outside of going back to bigger and bulkier non flexible panels.

New Pants

looks more tidy

end result

New LED Hats

this was my old Dreamstate Hat, it looks cool but it's heavy

so I made new ones that are much lighter

funny thing is the very first time I flew with the new hats, I was detained because of them :)

Upgraded LED Shoes with bright Shoelaces

I got new brighter shoelaces but the batteries didnt even last a day

So I made a connector to plug into the shoe's bigger batteries I upgraded

End result:

Extending battery life

I have a "few" battery packs, different sizes and weights, but the weight adds up:

The good news is that I'm now able to use smaller packs that can still output 60Wh, but only up to 12V. The bigger packs can do 100W at 20V and output up to 75Wh on a good day, although most of mine often seem to do less (they are of course rated for 99Wh)

in the process, I found out the Wh totalizer in these meters, is garbage and can't be trusted

nicer/bigger 100W capable pack (more than I need) with better totalizer

new test at 15V instead of 20V (the red boards can be changed to ask any voltage) with diodes to prevent backfeed

measuring the loss between 15V input and 5V output

trying again with 12V, we can also note the voltage drop at 1.4A

some surprising results, some 75Wh packs emptied quicker than expected, only got 65Wh from thsi one

a fun part of this exercise is figuring out if the Wh totalizers are even good

Here are the results I got so far:

So, what comes out of this is:

The smaller packs seem to work almost as well for a much smaller size, their main downside is they don't charge nearly as fast (the 100W packs can charge in 1.5h at max speed given the proper power supply).