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I’m trying to create a battery-powered RPi 3B+ system and am running into issues almost immediately due to the Pi’s power requirements. I’m testing using a 5V 3A wall power supply which is running into the official 7” Touchscreen, and from that to the Pi via the GPIO 5V pins. That seems to be working as long as I only use a mouse and keyboard, but if I plug in any other USB devices, such as an SSD, I start getting low power warnings. Trying to power it via a Nitecore 10000 mAh Powerbank rated to 5V 3A I get immediate low power warnings with only the screen connected and no other peripherals at all!

I admit I’m a neophyte when it comes to electronics, but I can do basic addition and I’m not running anywhere close to 3A of power draw with only the screen and RPi connected and idle.

One solution I’ve seen is to use a DC to DC buck converter, but how can I be sure that whatever I get will maintain the 5V above 2A? Seems like many of them drop low enough to cause problems as soon as there’s any load. It doesn’t help anything that the Pi seems to want 5.1V instead of 5.

Thanks for your help. I apologize in advance if these are basic questions, but I’ve researched it quite a bit and finding many people complaining about this but no verified solutions offered other than wall power. I’ll throw a car battery in there if I have to, but what needs to go in between?

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  • What diameter are the wires in your power connections?
    – CoderMike
    Feb 14, 2022 at 22:10
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    That’s a good question—the cables were thick, but who knows how much of that is insulation? But I think you’re on the right track, because bafflingly when I connected an unpowered hub to the battery and then connected up everything else via either the hub or the pi itself I managed to get everything working without any low power warnings! I guess I need to start sourcing USB cables from providers that list the wire gauge. Feb 14, 2022 at 23:50
  • Yeah, usually it's the cables for me when I get low voltage warnings. If the cables gauges are to small, the resistance will be too high, which in turn gives you a low voltage on your devices. You could verify this by making your own cables which are too thick. (Or buy cables which state their gauges, like you mentioned) Mar 29, 2022 at 7:58

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I have had similar problems in the past (Pi 4 + 7" HDMI screen), low voltage warnings. Solved it by using good quality USB cables (found this BASEUS brand on Aliexpress).

Using batteries (with associated circuitry) may be tricky due to voltage regulation under load, etc, but it can be done Powering Raspberry Pi 3 with 5v/3A Buck converter .

I am powering my system (cited above) with a LM2576 (a switched voltage regulator) getting 15V from a BMS (which is supplied by 6 lipo using this https://pt.aliexpress.com/item/32783727347.html ) with no issues.

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