Solved Trying to Power a Raspberry Pi and 5" LCD Screen with 1 Battery

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Hello everyone,
I've been working on making a portable Raspberry Pi for a while now, and it's so close to being done. Here's a link to my worklog that has more details: hackaday.io. Everything is working except my power setup. Basically I am trying to power this 5" display and the Raspberry Pi from one 3.7v lipo battery. The display runs on 5v, so you'd think I'd just need a simple boost converter to boost the 3.7v up to 5v, right? Wrong. I purchased this boost converter on Amazon, and it works perfectly fine for powering just the Pi or just the display, but plug both of those puppies in and the voltage drops down to 3v faster than you can say green eggs and ham. I'm assuming that the voltage booster doesn't supply enough amps (although its rated up to 3A) to power both devices. I also tried powering the screen directly from the 5v GPIO pins, which also drops the voltage down to 3v.

And that's what led me here, So I guess I should ask a question at this point, or maybe a few questions. Why is the voltage dropping? What is the solution to this issue? Is there a better boost converter that I could use or should I use the converter I have and use a different method to power the display?
 
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Maybe you can test how much power each of the components consume individually with a multimeter, and also individually how much power the booster can supply. My theory is that that converter cannot actually supply 3A @ 5V, but also your components can draw more than 3A (peak). Looking at the product page it seems its suitable for 2A constant and 3A peak. Could be that your total current draw is a bit over that. A Raspberry Pi 4 can already draw 3A peak. So your display is probably 0.5A. I'm not sure what the input voltage rating of the Pi or the screen are, but maybe you can boost the voltage a bit (to 5.5V or so) to bridge the gap. But I suppose measure first just to get a better idea.
 

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Hello everyone,
I've been working on making a portable Raspberry Pi for a while now, and it's so close to being done. Here's a link to my worklog that has more details: hackaday.io. Everything is working except my power setup. Basically I am trying to power this 5" display and the Raspberry Pi from one 3.7v lipo battery. The display runs on 5v, so you'd think I'd just need a simple boost converter to boost the 3.7v up to 5v, right? Wrong. I purchased this boost converter on Amazon, and it works perfectly fine for powering just the Pi or just the display, but plug both of those puppies in and the voltage drops down to 3v faster than you can say green eggs and ham. I'm assuming that the voltage booster doesn't supply enough amps (although its rated up to 3A) to power both devices. I also tried powering the screen directly from the 5v GPIO pins, which also drops the voltage down to 3v.

And that's what led me here, So I guess I should ask a question at this point, or maybe a few questions. Why is the voltage dropping? What is the solution to this issue? Is there a better boost converter that I could use or should I use the converter I have and use a different method to power the display?
Your problem is almost certainly that cheapshit regulator. Nearly everyone who tries to use those runs into current supply issues, and occasionally they catch fire. You'll want something of better quality, but I'm afraid I don't know any drop in solutions that can supply the required current. I can only suggest maybe having a go at designing a custom boost reg PCB yourself, or changing the battery setup to a 2S arrangement and using something like a PTR08060W step down reg.
 
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Maybe you can test how much power each of the components consume individually with a multimeter, and also individually how much power the booster can supply. My theory is that that converter cannot actually supply 3A @ 5V, but also your components can draw more than 3A (peak). Looking at the product page it seems its suitable for 2A constant and 3A peak. Could be that your total current draw is a bit over that. A Raspberry Pi 4 can already draw 3A peak. So your display is probably 0.5A. I'm not sure what the input voltage rating of the Pi or the screen are, but maybe you can boost the voltage a bit (to 5.5V or so) to bridge the gap. But I suppose measure first just to get a better idea.
Ok, I tried increasing the voltage up to 5.72v, but it still diddn't work. This time the voltage fluctuated between about 3.15v, 4.15v, and 5.65v, but wasn't stable enough to power both devices.
 
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You need a RetroPSU from Helder. It'll power everything without low power warnings.
Yeah, that's probably my best bet. I wanted to try my current setup with the cheap voltage booster first though since the RetroPSU is expensive and takes forever to ship all the way to the US.
 
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I would like the RetroPSU but they don't ship to England, so using this
Not sure if you can get it in the USA, seems to be working ok
 
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Yeah, that's probably my best bet. I wanted to try my current setup with the cheap voltage booster first though since the RetroPSU is expensive and takes forever to ship all the way to the US.
I think we are talking about two different things.

Helder ships from the USA and they're not as expensive as the PowerBoost 1000C.

 
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I think we are talking about two different things.

Helder ships from the USA and they're not as expensive as the PowerBoost 1000C.

Oh yeah, that's what I was talking about. I guess I assumed it came from the UK or something since shipping time says it takes up to 30 days to arrive
 
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I would like the RetroPSU but they don't ship to England, so using this
Not sure if you can get it in the USA, seems to be working ok
The link doesn't work, could you comment on this and post the link again?
 
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Oh yeah, that's what I was talking about. I guess I assumed it came from the UK or something since shipping time says it takes up to 30 days to arrive
That might be a general shipping frame for sales overseas. I know I'm CONUS and they always get to me in a very reasonable amount of time.
 
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