Has anyone ever had this problem? Raspberry Pi3B+ running under voltage all the time in a car. I have purchased a high quality 5V power supply rated to 10 amps but not put it in yet, so I'm running off a 2.4 amp tablet charger.

I have two USB hubs attached and they CAN be powered but I have not yet. They are attached with 6 foot cables that run through the cars interior and while its not impossible a cable got pinched it is unlikely. They were routed carefully and protected. then I attached the USB hub and put just those visible in the car. Each USB hub is attached to a single port on the raspberry pi.

Initial setup in December; iNext controller fries after about a week. No reason I can determine, but its in a car so... maybe it got stepped on/spilled on/who knows what. I went through 3 more that fried, and it seemed to be happening at an increasing rate. Bought a single Buffalo controller. That seemed to be doing well, and either the next Buffalo controller I bought was DOA or fried instantly. And it was at that point that it occurred to me that I think all fried controllers came out of my LEFT USB hub.

I am not positive, cause cords get tangled up and I've definitely just pulled some out and gone into the house to test them.

Has anyone ever had a Raspberry Pi fry controllers? Has anyone ever had a USB hub fry controllers? At the moment I am not using that hub, and if I get no more controllers fried I will assume that is the problem (I'm looking at YOU SABRENT!), but I must confess--I'm so curious if anyone else has ever had a similar problem and if anyone can speculate how it is even possible to fry these things with such low power!?

As an aside the Car itself did have a bad ground. A strap that attaches to one of the motor mounts got pinched by the motor mount and broke. I replaced it with a fantastic ground and the LAST controller fried after this repair I think.

  • what does this mean? running under voltage
    – jsotola
    Mar 8, 2019 at 6:44
  • what is the output voltage of the left USB hub? ..... have you done any troubleshooting? .... it seems like you are expecting the problem to go away by itself if you throw enough controllers at it.
    – jsotola
    Mar 8, 2019 at 6:46
  • It's pretty much impossible to troubleshoot an electrical problem without taking a good look at the wiring and making measurements. One thing I'm certain about is that a USB hub will not fry controllers when it's powered properly. Mar 8, 2019 at 9:34
  • Running under voltage means that the Rpi is indicating, at many if not all times, that it is running at less than acceptable voltage. 4.65v I believe. No. I had no intention of throwing controllers at the problem. I thought the problem was cheap controllers until it duplicated with an expensive one. Mar 9, 2019 at 11:59
  • Thanks Dmitry. That helps, because I was not certain of that. So I will be testing elsewhere. Mar 9, 2019 at 12:01

1 Answer 1


The USB Jacks on the Raspberry Pi simply passes through the input power supply. I suspect a wiring fault would fry the RPI before it fries the controller . Instead , too high a voltage is my suspicion I would use a multimeter to confirm the USB voltage at the business end of your USB cable

. Short circuits between power lines would not likely affect the controller but damage the pi or it's power supply , short circuit between data and power may damage the logic on USB SNES controller but would likely also be associated with intermittent connections and other glitches. The fact that your controllers fail with such regularity after functioning fine indicate to me some fundamental power supply issue, but may still be associated with a short circuit , a multimeter would be useful there as well .

I would try a powered hub and replacing the power supply for the Raspberry Pi . I would also replace the cabling while I was at it .

Note that significant power AND ground voltage spikes may be present in a car environment , so isolated supplies are highly recommended . Never use chassis for return current/ground as it is extremely electrically noisy. Note that if the ground "jumps" or "falls" due to noise, the effective input voltage also jumps, even when using a regulator.

Internally the raspberry pi has a regulator for 3.3V that can handle a wider range of input voltages even up to 9V, however if your power supply is supplying too high a voltage it may still cause damage to downstream devices.

The USB spec is very narrow, the required tolerance is 4.4-5.25V so devices can be very picky about input voltage and may not tolerate much more than 5V even if the RPI is ok, the input votlage clamp on the raspberry pi is at 9.2V so up to that voltage may be delivered to attached devices if there is a faulty or incorrect power supply delivering too high a voltage.

  • Thank you so much. Using that info I will test with a multimeter first. I have a powered hub just waiting to go in, along with a step down transformer rated at 10 amps. I know, overkill but I was hopping it would be very clean and stable at a third capacity. I didn't want to put them in until I knew what was wrong (and I did not know Rpi just passes input voltage along). I WAS planning on grounding to the chassis, so thank you for that too. I'll--not do that. :) Mar 9, 2019 at 11:54

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