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[Hardware] Power Help



  • Hey guys!

    So I'm trying to get my PSX system up and running, and I'm having a really hard time troubleshooting my power supply system.. I have a micro USB power supply .. this one to be exact:
    http://iessentials.com/power/home-power/2-5-amp-tethered-micro-usb-wall-charger-compatible-with-raspberry-pi.html
    I bought it at MicroCenter when I bought my Pi3 for this build. It advertises on the plug itself as being 5.1v and 2500mA. The package and website say it's designed to work with the Raspberry Pi. HOWEVER.. whenever I'm using it, I get a lightning bolt symbol on my screen, indicating under powered. At first I thought this was because I'm connecting through a Mausberry circit (spring loaded), but when I take that out of the equation and plug it directly into the Pi, I still get that lightning bolt. So my first question is:

    Is there a way to check and see how much power the Pi is requesting (via terminal) and how much it is receiving?

    Now for the interesting bit. I have an OLDER power supply, from a CanaKIT. It's label indicates 5v and 2.5A. So we're cutting away .1 volts, and the 2.5A vs 2500mA is the same right? Then why does THIS power supply work flawlessly when connected directly to the Pi? Does that .1v really cause the Pi to not work right? I thought the fault tolerance was +/- 5%? Also, why does this supply, that works when directly connected, not work through the switch? Thus leads to my 2nd question:

    Has anybody had any success with directly soldering to a spring loaded Mausberry circuit and the Pi without getting the lightning bolt?

    In my previous attempt using this style circuit (the mini Sega USB hub) I got that same lightning bolt. Is it possible my soldering job is bad?

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  • Global Moderator

    important to note that the claimed specs on a power supply often aren't reliable.



  • @hansolo77 first did you verify the power supply is actually 2.5 amps by looking at the rating on the charger? Ibhave had the wrong items in the wrong packages from microcenter before.

    Second, any time you pass power through another component wheather that be another wire, connector or switch you are adding resistance which causes a drop in voltage.

    Last, you are also experience voltage loss at your sauter connection. If you did a good job it should be minimal, but if you don't have a strong connection you could be seeing a large voltage drop. You have a lot of variables at play here so it is hard to determine the cause. I am assuming you are not running any overclocking?



  • On my setup which is a modded SFC with direct soldering only, I've had lightning bolt issues on a $6 2.5A charger sometimes. Once I got the official pi adapter, I've had no problems. I do notice more power than normal is required when rerouting through all these wires. For the inside I'm using wires from an old PC psu to prevent as many power issues as possible. My setup is Pi to power switch, power switch to usb port, usb port to 3-4ft of whatever gauge wiring the official pi ac adapter uses. Shorten the wires as much as you can.

    As it was already said, not all ac adapters are made equally.



  • Well it doesn't really matter now. :( I think I burned up the Pi. I decided to go back over the soldering because I noticed when I "jiggle" the wires, the power cut out. So I went back through and actually got a good solid solder with the Mausberry.. I actually managed to get the new wires all the way through the circuit board and soldered it on the other side like a real professional. Then I tried to re-solder the connection on the Pi. My 5v pad broke off, but I managed to get solder back on it to where it was a good blob and not just a tiny trace. But somehow I managed to bridge the 5v and Ground pads. When I tried to fix it, I soldered the 5V to one of the USB connector feet. When I thought I had it all fixed, and a good clean solder on the wires, I tried to power up. Nothing. I can't even get power on the original Pi power plug now either. So this Pi is now trash. UGH!!!! Gonna have to wait to get a new one now. I hate my life. Just can't win.



  • @hansolo77 i am sorry to hear that, it sounds like a bummer.



  • Yeah, it's pretty sucky!



  • @hansolo77 at least on the bright side the pi's are fairly reasonably priced.



  • True.. I'm going to go with my first best option.. the direct plug - inline switch. I ordered 3 of those spring loader ones during a sale when I did the Sega build. I just figured I could do the same thing, without remembering how badly I suck at soldering. I'm getting a heck of a lot better than I used to be. You'd die laughing if you saw my original PlayStation modchip solder job. All the contact points got lifted and I had to solder to traces, then I put down 3 sticks worth of hot glue to make sure it stayed. Not pretty at all!

    I'm going to go ahead and marked this as resolved then, since there's not really anything anybody can do at this point. The Pi is toast. The switch circuit might be ok, doesn't appear like any damage or crossed over traces exist. I'm off to the internet store for a new Pi and circuit.



  • While I've been soldering for over 15yrs, I'm still not that great at it. Instead of soldering the wires directly to the pi, I just bought a pack of microusb connectors for $1 and soldered the thick wires to that. Wasn't easy (I broke two of them) but it's tons safer. I finished it off with a ton of hot glue for support.



  • LOL! Hot glue... computer nerd's duct tape.



  • Hot glue is love. Hot glue is life. My wiring still works a year later :P



  • If you want an easy life, there are 5v and gnd pins hidden in the gpio pins they can be used for in and out.

    The lightning bolt is low voltage rather than low power. Some power supplies can't keep to 5v when the current draw increases



  • @moosepr correct, per my earlier post there is to much voltage drop with all the wires ands connections.



  • Yeah, the disappointing thing was that even with nothing connected other than the controller, I was getting the lightning bolt. But when I switched to a different power supply and had it directly connected, it went away. I thought a 5.1v would be better than a 5v because it gives it that extra .1. Guess I was wrong. What would happen if you used like a 6v? Would it burn out the circuits?



  • @hansolo77 yeah 6v would let the magic smoke out! The 5v one is probably more precise with its voltage



  • So whats a good power supply to get? That iEssentials one, even though specifically marketed with Raspberry Pi logos on the package is clearly crap. I have 2 of them and they both did that. I've had the CanaKIT supplies in the past, and they've been pretty solid. Is there a better brand? What about the charging adapters that are basically female USB plugs that you connect a standard USB->microUSB cable to? Like this:
    alt text



  • @hansolo77 What's wrong with with using the official pi power supply?

    0_1499556238943_pi.jpg



  • Nothing really. It's probably more expensive coming from the UK and overseas shipping can get crazy. I have to be realistic and use supplies I can easily get my hands on.



  • @hansolo77 I got mine from arrow.com, a US seller back when they had the free pi3 deal. Not sure if that's the best place but there are other US sellers. Not sure what made you think it was Uk exclusive.


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