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That God %$#@ Lightning Bolt

  • @unrealduke said in That God %$#@ Lightning Bolt:

    RPi's are designed to use USB power

    Not true, they are designed to use a micro USB connector to receive power!

    I should be easily able to power the RPi with at least 4.75 Volts without trouble

    Why do you think this?, it is just not true, especially if you are using a charger. It may boot but when you try to draw current from that, the voltage collapses and so does your Pi. A power supply is regulated - this is a very important concept to understand. In my cabinet builds, I use boxed regulated power supplies similar to those found in PCs but smaller. With those, you can power all sorts of other stuff together with your Pi. RGB LEDs for example. Then there is the whole USB cabling issue - choose a poor one and it will fail to deliver the required power even WITH the correct specifications.

  • @unrealduke Take a look at this for an example. You can wire these up to a build with your own wire and they are rock solid. That said, I have no issues with the official PSU with an Ipac, keyboard and two controllers connected at once with an LED Marquee. I have had issues with a dedicated usb power supply rated at 3A. Each socket was not capable of delivering the minimum spec. It's obvious use would be to charge three things at once like a headset, a phone and a camera. I think this is the issue you are facing. A typical USB 2 port will source a maximum of 500mA and a USB 3 port around 900mA. Some dedicated charging ports source about 1.5A which gives a false sense of security as your hardware appears to work until you stress it. All are inadequate regardless of the rated voltage.

  • @unrealduke Finally, there is a script that I saw on here quite a while ago. It disables the power restrictions. I have not tested it and when disabling things like this, you should be cautious as these are in place to preserve your pi over time. Anyway, you can take a look here.

  • If you know anything about building electronic circuits you'll know that there are hundreds of difference schematics of varying quality for any given task.

    You can make a 5v power supply from 2 diodes, an LM317 with 2 electrolytic caps, 3 resistors, a potentiometer and a breadboard... or you can make a 5v power supply from a 4 diode bridge rectifier, noise reducing ceramic caps in parallel with electrolytic filter caps, dropout and linear voltage regulator ICs and a host of other components.

    Both will show 5v on the output rails when you connect a multimeter, but the cheaper supply may have voltage drops and spikes ranging in the milli to nano second range, signal noise or a host of other problems.

    When you get a cheap supply (aka charger), it's cheap for a reason, the builders cut corners and did the bare minimum to get the "required" output into spec . Phone chargers do not need to hold consistent cc/cv since batteries have wide voltage tolerance, sensitive electronics relying on clean power and cv will not fare so well.

    The only way to accurately check the quality of a power supply is to connect it to the pi, power it up and check the test pads (+pp7, -pp6 on a pi 3) on the bottom of the pi with a scope and view the spikes and dips in voltage when the pi draws a load. A multimeter is too slow to show voltage differences in the milli/nano second ranges, but a decent scope will show you just how crappy that mystery wall wart from Goodwill really is.

    To put it simply, you get what you pay for.

  • Let's see how cheap these things really are...
    alt text
    Interesting enough they are rated at 5 volts.

  • @unrealduke Canakit are decent supplies. If youre getting a lightning bolt from a those, then theres something wrong with your setup. Too many connections to the GPIO, power hungry usb adapters or just a bad pi board.

  • @unrealduke i haven’t seen any problems with my Canakit PSU, admittedly it only drives a Pi and a zero delay joystick interface with illuminated buttons.

  • @capeman my canakit gives me the occasional lighting bolt on my overclocked pi3. I have heard others say the same. I switched to a different power supply and no longer have issues.

  • I had no intention of overclocking my RPi. Just the idea of using a regular USB power supply that is commonly available to power it. Since I have two RPi's I bought 2 proper power supplies which hopefully will never give me a "Lightning Bolt" ever again. Unfortunately I had to wait until the guy who sold the things opened his store. Frequently he had a sign in the door that said "Back in 1 Hour".

  • @quicksilver said in That God %$#@ Lightning Bolt:


    This is the power supply that I'm using with my pi3, I am also using the super kintaro case. I have had no issues with this power supply and I'm overclocked.

    Just an update to reclaim my thread. ;)

    This has been working just fine for me. Haven't seen a lightning bolt since I started using it. Only hardwired 3A cables for me from now on. Thank you all for your suggestions. :)

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