bomby587
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Powering pi via battery?

Fri May 28, 2021 6:19 pm

Anyone have any recommendations for any solutions to power a pi 4 via a battery etc battery hat (specific model) or power bank eg?

LTolledo
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Re: Powering pi via battery?

Fri May 28, 2021 8:46 pm

doing what type of task? how long do you plan to have the RPi operational?
1Hr?
10Hrs?
1000Hrs?
1,0000Hrs?
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bomby587
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Re: Powering pi via battery?

Fri May 28, 2021 9:45 pm

I plan to use the pi as a programming/ general pc on the go. So between 5-10 hours on batteries

I’m more asking the questions of do I use a power bank or a battery HAT and power through gpio

I’m also not sure what size battery?


I’m thinking of going with the HAT way however is there any risks powering through gpio eg passes rip protection and what products would u recommend as I have heard mixed reviews about certain models

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Gavinmc42
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Re: Powering pi via battery?

Fri May 28, 2021 10:17 pm

Try a Cordless drill battery and a switching, step down regulator.
The Pi draws max 2Amp at 5V, 1Amp 10V, 0.5amp at 20V
2Ahr battery is 4 hrs, 4Ahr is 8hrs.

A powerbank is rated at 3.7V and has a step up regulator.
5Hrs at 5v 2A is about 7Ahr powerbank, 10hours is 14Ahr.

Napkin calculation ;)

Pi4 is the only one equal to portable PC, it can use up to 3Amp 5V
Portable screen?
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bomby587
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Re: Powering pi via battery?

Sat May 29, 2021 9:30 am

I’m running pi 4, I won’t need a screen since I’m blind

I don’t want to use a drill battery as I’m building a portable case

Should I go powerbank or battery power hat?

bomby587
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Re: Powering pi via battery?

Sat May 29, 2021 11:18 am

Im using a screen reader, which conveys whats on the screen in audio format.

Fun fact: Blind people can use a raspberry pi through the use of the screen reader Orca which is built into raspberry pi os

Im also using an hdmi dummy plug which allows the pi to behave normally without a screen.

Im appalled at the ignorance of some members of this forum!

LTolledo
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Re: Powering pi via battery?

Sat May 29, 2021 11:26 am

bomby587 wrote:
Sat May 29, 2021 11:18 am
Im using a screen reader, which conveys whats on the screen in audio format.

Fun fact: Blind people can use a raspberry pi through the use of the screen reader Orca which is built into raspberry pi os
well... that clears it...
as it was not clearly stated in the previous post lead me to suspect something dubious was going on...
"Don't come to me with 'issues' for I don't know how to deal with those
Come to me with 'problems' and I'll help you find solutions"

Some people be like:
"Help me! Am drowning! But dont you dare touch me nor come near me!"

bomby587
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Re: Powering pi via battery?

Sat May 29, 2021 11:35 am

LTolledo wrote:
Sat May 29, 2021 11:26 am
bomby587 wrote:
Sat May 29, 2021 11:18 am
Im using a screen reader, which conveys whats on the screen in audio format.

Fun fact: Blind people can use a raspberry pi through the use of the screen reader Orca which is built into raspberry pi os
well... that clears it...
as it was not clearly stated in the previous post lead me to suspect something dubious was going on...
Is a powerbank better than a battery HAt through gpio for raspberry pi? and how long will 10000mah last?

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mahjongg
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Re: Powering pi via battery?

Sat May 29, 2021 12:18 pm

well, if you are blind, then this post is eligible for the “Assistive technology and accessibility” section, which is precisely created for these kind of subjects, and if you had posted there wouldn't have caused misunderstandings.

so moved there, and removed offensive posts.

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mahjongg
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Re: Powering pi via battery?

Sat May 29, 2021 12:21 pm

bomby587 wrote:
Sat May 29, 2021 11:18 am
Im appalled at the ignorance of some members of this forum!
You did not mention you were blind, so things like that will happen, also most people have no idea blind people can use a raspberry PI with a screen reader.
bomby587 wrote:
Sat May 29, 2021 11:18 am
Im also using an hdmi dummy plug which allows the pi to behave normally without a screen.
a dummy HDMI plug is not necessary, just force a fake display setting in config.txt, and a frame buffer for that size will be created.

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Re: Powering pi via battery?

Thu Jun 03, 2021 5:05 pm

Unless you actually require the processing power of a Pi4B, I'd suggest and earlier--and less power hungry--Pi to reduce power consumption. Something like a Pi2Bv1.2.

To determine required battery capacity, covert all power to Watts and capacities to Watt-hours. Recognize that voltage conversion will incur losses. Also that you can't safely drain a battery all the way to zero charge. Rough rule of thumb is to assume that the powered device will be able to use about half of the quoted capacity.

Since a Pi4B is specified for 3A at 5V, or 15W, to run for 5 to 10 hours, you should look for a battery capacity that exceeds 75Wh and approaches 150Wh. If you're going to travel with it, TSA rules prohibit Lithium batteries exceeding 100Wh. TSA limit works out to about 28Ah for a Li Ion/ LiPo powerbank.

I have run a Pi2Bv1.1 with 7" RPF display (which you don't need) from a 10Ah (=37Wh) powerbank for 5 hours, so a 20+Ah (=74+Wh) one should meet the upper end of your range and still fall within the TSA limit.

bomby587
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Re: Powering pi via battery?

Fri Jun 04, 2021 11:15 am

The 15w of pi 4b is at peak power draw and from research general use of the pi for programming and general computing the pi draws about 3-5W

What would this be in milli amp hours?

Should i go for a battery HAT/ board or a powerbank?

W. H. Heydt
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Re: Powering pi via battery?

Fri Jun 04, 2021 5:14 pm

bomby587 wrote:
Fri Jun 04, 2021 11:15 am
The 15w of pi 4b is at peak power draw and from research general use of the pi for programming and general computing the pi draws about 3-5W

What would this be in milli amp hours?
"milliAmp-hours" is a measure of energy. It's power (an instantaneous measure) times time. Since a Pi runs on 5 volts direct current, the power rating, Watts, is volts times amperes. So 3-5W would be 0.6-1A.

While 3-5W may be idle power, if you want to do anything, or have attached devices, it will require more. I don't recommend using idle power to gauge battery requirements. Better to use the specified--maximum--power requirement. That way, you are far less likely to discover that your battery can NOT supply enough current for higher loads.

Keep in mind as part of this advice that I majored in EECS, so I bring a conservative, engineering perspective to this sort of discussion. I prefer to, at least modestly, over-spec a power source than to find out by experience that trying to hit a minimal spec leads to failure.

bomby587
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Re: Powering pi via battery?

Sat Jun 05, 2021 3:13 pm

I have read that certain power banks have fried a pi zero in the past because they had Qualcomm fast charging or similar fast charging and this lead to the pi receiving over 5v.

I take it the power bank was faulty, I’m afraid of buying a power bank which can deliver above 15w

Another question is would a 20000 mah battery be enough?

Do I need a battery with USB PD? I don’t understand what this technology is?

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rpdom
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Re: Powering pi via battery?

Sat Jun 05, 2021 3:24 pm

bomby587 wrote:
Sat Jun 05, 2021 3:13 pm
I’m afraid of buying a power bank which can deliver above 15w
The Watts can't be too high. That is only what the power bank can supply if needed. As long as it can provide enough it is good.

The Volts are critical. It must be 5V. Offer a Pi 4B 5V at 5000W and it will take 5V at 5 to 15W. Offer it 7V at 3W and it will die.
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Re: Powering pi via battery?

Sat Jun 05, 2021 4:56 pm

bomby587 wrote:
Sat Jun 05, 2021 3:13 pm
I have read that certain power banks have fried a pi zero in the past because they had Qualcomm fast charging or similar fast charging and this lead to the pi receiving over 5v.

I take it the power bank was faulty, I’m afraid of buying a power bank which can deliver above 15w

Another question is would a 20000 mah battery be enough?
20Ah (using mAh is silly marketing-speak) at 3.7v (nominal cell voltage) is 74Wh capacity. That would, in theory, provide 15W for a bit under 5 hours. In practice, perhaps 4 hours. If running at less than full load, more. Possibly considerably more.
Do I need a battery with USB PD? I don’t understand what this technology is?
"PD" is "Power delivery". It's a way for the device being powered to "negotiate" how the power is delivered (voltage as well as current). The default (assuming the powering device is built correctly and follows specification) is 5v. There was a design error in the early Pi4B that wouldn't negotiate correctly and PD power supplies would provide the correct 5v, but limit current to around 100mA, which is far too low to run a Pi4B. If you've bought your Pi4B in the last year or so, this will not be an issue and a properly made PD PSU will work.

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Re: Powering pi via battery?

Sat Jun 05, 2021 8:28 pm

W. H. Heydt wrote:
Sat Jun 05, 2021 4:56 pm
bomby587 wrote:
Sat Jun 05, 2021 3:13 pm
Do I need a battery with USB PD? I don’t understand what this technology is?
"PD" is "Power delivery". It's a way for the device being powered to "negotiate" how the power is delivered (voltage as well as current). The default (assuming the powering device is built correctly and follows specification) is 5v. There was a design error in the early Pi4B that wouldn't negotiate correctly and PD power supplies would provide the correct 5v, but limit current to around 100mA, which is far too low to run a Pi4B. If you've bought your Pi4B in the last year or so, this will not be an issue and a properly made PD PSU will work.
All true, but you do not need PD, nor will it give any benefit whatsoever when used with a Pi.
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TheRedReactor
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Re: Powering pi via battery?

Thu Jun 10, 2021 6:22 pm

In my experience with power banks is that they are mainly designed to supply a steady current as you would see when charging a tablet or phone, and whilst they might power up a Raspberry Pi, they are terrible at keeping their voltage constant when the current demand is very peaky. Not only will you see the lightning symbol but if I plugged my USB hub in with things like keyboard/mouse/webcam it often crashed the whole system.

I would recommend choosing a battery power supply designed for the Pi, that is capable of delivering the amps you need for more robust operation. Remember that as the battery voltage drops, it has to supply more current to deliver the power you need. So check carefully how much current the battery can supply - a design with 2 batteries in parallel will obviously cope more easily here. Likewise, your external power source should be able to deliver the current for your system as well as the current to charge the battery at the same time.

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