How useless is shortening power train wires for voltage devices?

Electronics
#1

I have a rasberry pi 3B + that has had voltage problems. From what i understand the load on usb and gpio of raspberry proportional voltage. This means more the load the more i am going to get the low voltage error. Is that correct? and if so how useless is shortening the power cord on power supply to increase the feed back and voltage regulation from power supply to pins of processor. As well i believe this stop varying voltage drops across the input of raspberry pi

as loads increase and decrease.

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#2

Some versions of the pi do better if power intensive USB accessories are plugged into a powered USB hub.

The issue on some versions isn’t even on the power supply side, but rather a poly fuse on the board that drops too much voltage as the current draw goes too high.

#3

I would get a power supply and cable known to be good for a Raspberry Pi. There are many good options that don’t cost a lot. For example this one on Amazon.

https://www.amazon.com/Listed-iUniker-Raspberry-Supply-Switch/dp/B0B79FVPQ4/

Micro Center has some too. I suspect the power supply you have is fine. The micro USB adapter look sus. Most micro USB stuff isn’t capable of handling 3 amps. This is probably why they went to USB C for the Raspberry Pi 4. It’s so much more reliable for 3 amps (and more).

#4

One more thing. If you have a USB power supply that does 3 amps then these cables are fantastic. They’re thicker gauge than most USB cables. I’ve used then for years with USB battery packs and USB adapters for Raspberry Pi and some other relatively high current stuff (flashlights, custom boards).

https://www.amazon.com/Sabrent-6-Pack-Premium-Cables-CB-UM63/dp/B011KLFERG

1 Like
#5

The short answer here is it is effectively useless in this case as the problem with earlier PIs is the way they condition and protect the 5V USB power lines.

IIRC (without looking at the schematics) you need to either supply 3.3V to the 40 in connector to guarantee performance, or separate the 5V supplies for all external USB devices to not pass though the PI. I used external powered hubs in most cases, but Y cables are available that do this. Supplying 5V to the 40 pin connector might work, but I don’t remember.

I see the problem on some Zeros and 3s that have no external USB loads. It’s annoying.

Oz

#6

Couldn’t help myself.

Suppling 5V to J8 pins 2,4 (and using the ground pins on 6, 9, 14, 20, 25, 30, 34 and 39) bypasses the troublesome 3B USB current protection circuit.

Oz