JPrograms
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Battery Options for handheld gaming device

Mon Dec 18, 2017 5:24 pm

Not sure if this is the right place to post this.
I am thinking of making a handheld gaming device with an RPi 3 and official 7" touchscreen (Nintendo Switch style?) and was wondering what battery options I would have for it. I've never really powered an RPi from a battery, so I'm a little new to this. I've looked at the PiJuice but that isn't released yet, is bulky, and is pretty expensive. Would a LiPo battery work? If so what mA should I use? It would have to be able to power both the pi and touchscreen.I would also like a battery that can be charged while powering the device, and possibly a way to monitor battery level. Any feedback is appreciated!

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jcyr
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Re: Battery Options for handheld gaming device

Mon Dec 18, 2017 7:43 pm

I've used Lipo. It is available and relatively safe technology provided you adhere to proper charging protocol. This probably means you'd rely on a commercially available charger rather than building your own. Lipo charging can be a delicate thing, where over charge/discharge can destroy the battery.

Now to answer your question:

You could use Lipo. The size of the battery required depends on your power requirements and how long you wish to run between charges. The math is relatively straight forward. Based on what you say (Pi3 + screen at aprox. 15 watts), you'll be surprised at how big a battery you'll need to use to run for even an hour. You'll also need to regulate Lipo voltages down to 5 volts. The RC crowd consumes volumes of these regulators (I think they call them BECs) so you can buy them for next to nothing.

Not sure the Pi3 is the best choice for handheld due to its high power needs.
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JPrograms
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Re: Battery Options for handheld gaming device

Mon Dec 18, 2017 8:50 pm

Thanks! I was thinking pi3 because of wifi/bluetooth/fast processor, but I might try a pi 2. I was thinking this battery: https://www.adafruit.com/product/354, along with https://www.adafruit.com/product/2465 to regulate power/charge the battery. Even if I have 1-3 hours of run time I would be happy with that. I could just use a power cable, but having a portable device would be nice. If you know of other batteries/regulators that work that would be great.
EDIT:
This url: https://learn.adafruit.com/7-portable-r ... t/assembly show how to make a Raspberry Pi 2 tablet with a 2500 mA battery and they say that lasts a little over two hours. The battery I was thinking is a 4400 mA battery, so that should last around 3 hours with the Pi 3, correct?

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Imperf3kt
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Re: Battery Options for handheld gaming device

Mon Dec 18, 2017 9:20 pm

You cannot use the Adafruit 1000C with a Pi3B as it is current limited to 1 Amp. For a 3b + screen you'll need at least 1.5, more if your Pi will be doing heavy tasks or have USB accessories.
Stephen Hawking, rest in peace.
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JPrograms
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Re: Battery Options for handheld gaming device

Mon Dec 18, 2017 9:34 pm

Ok thank. So the PowerBoost will not work, but the battery would (If I got a regulator)?
Would the Adafruit regulator work for a pi 2?
EDIT:
One other idea I had was using a pi A+, as that has a touchscreen interface. I will have to check power requirements though
Last edited by JPrograms on Mon Dec 18, 2017 9:42 pm, edited 1 time in total.

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jcyr
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Re: Battery Options for handheld gaming device

Mon Dec 18, 2017 9:39 pm

Why not a Pi0W. It has much lower power requirements and also includes WiFi and Bluetooth. Much less CPU capacity though, but for sigle threaded gaming it might work.
If you want your child to get the best education possible, it is actually more important to get him assigned to a great teacher than to a great school. -- Bill Gates

JPrograms
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Re: Battery Options for handheld gaming device

Mon Dec 18, 2017 9:43 pm

I was thinking a pi 2, 3, or A+ since those have an official touchscreen interface, and that is what I am using.

JPrograms
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Re: Battery Options for handheld gaming device

Mon Dec 18, 2017 9:50 pm

So it is looking like a pi A+ would be the way to go. It only uses 700mA, so the battery I was thinking would work for it. The problem would be processing speed, but I don't know where to find that information.

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fruitoftheloom
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Re: Battery Options for handheld gaming device

Mon Dec 18, 2017 9:59 pm

JPrograms wrote:
Mon Dec 18, 2017 9:50 pm
So it is looking like a pi A+ would be the way to go. It only uses 700mA, so the battery I was thinking would work for it. The problem would be processing speed, but I don't know where to find that information.

https://www.raspberrypi.org/help/faqs/#topPower


The A+ / B+ / Zero's all use the same SoC:

https://en.wikipedia.org/wiki/Raspberry ... ifications
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JPrograms
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Re: Battery Options for handheld gaming device

Mon Dec 18, 2017 10:14 pm

So, maybe A+ isn't such a great idea for speed. I've used a Pi0W and it seems slow, so 3/4 the speed of that would seem very slow. Although for my purposes it may be fine. I am planning on just running some homemade python/pygame games on it, so it could be fine.

So going back to my original thought, I could use a PiJuice once they are in stock. That would be more expensive, but it would be much easier (and safer :P ) for me. That would allow charging while powering, smart shutdown, and some RGB LEDs too :D .

JPrograms
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Re: Battery Options for handheld gaming device

Mon Dec 18, 2017 10:15 pm

One question about the PiJuice: Would that supply the power needed for the touchscreen too?

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Imperf3kt
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Re: Battery Options for handheld gaming device

Mon Dec 18, 2017 10:36 pm

After some thought, allow me to correct some slight misinformation I spread.

The Adafruit 1000C should not be used to power a Pi3b.
Thats not to say it cannot, but rather that your Pi will only have 1A available.
An average Pi3b uses around 350mA to 700mA, IIRC (need to check toppower link again)

What you could do, is power the Pi with the 1000C module and power the touchscreen's backlight from the battery directly by piggybacking the input on the 1000C

I have a 5" screen which uses around 600mA, so you're looking at about 1500mA once you account for USB accessories.


The only thing you do need to be careful of is the battery. Look for one that is at least 2200mAh (you have 4400mAh, so should be okay) and has a discharge rating of 2C or more, preferably more.
Also beware the battery may be say 6C, but the wires connected to it may restrict that to 1C. Be prepared to replace wires as necessary.
Stephen Hawking, rest in peace.
8 January 1942 – 14 March 2018

JPrograms
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Re: Battery Options for handheld gaming device

Mon Dec 18, 2017 10:44 pm

I probably will not have any USB accessories once I have it finished and running off the battery, and if so I will probably have it plugged in differently (Probably will have removable back panel to access components) That being said, the battery will only power the RPi and touchscreen, along with about ten buttons and two joysticks connected via GPIO

JPrograms
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Re: Battery Options for handheld gaming device

Mon Dec 18, 2017 10:46 pm

Also you said "piggybacking" the touchscreen, what exactly does that mean? (Sorry, a little new to battery/power stuff :) )

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Imperf3kt
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Re: Battery Options for handheld gaming device

Mon Dec 18, 2017 11:51 pm

Stephen Hawking, rest in peace.
8 January 1942 – 14 March 2018


JPrograms
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Re: Battery Options for handheld gaming device

Wed Dec 20, 2017 11:46 pm

So just the RPi, touchscreen, 2 joysticks and ten buttons, the original battery/regulator will work?

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Imperf3kt
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Re: Battery Options for handheld gaming device

Thu Dec 21, 2017 8:45 pm

Possibly.
It depends how hard your Pi is working.
Stephen Hawking, rest in peace.
8 January 1942 – 14 March 2018

JPrograms
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Re: Battery Options for handheld gaming device

Fri Dec 22, 2017 12:25 am

So if it was working too hard, what would happen?
Also, I found this: http://www.stefanv.com/electronics/a-co ... ablet.html, and this: https://learn.adafruit.com/7-portable-r ... it-diagram, and both use the Adafruit PowerBoost 1000C.

JPrograms
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Re: Battery Options for handheld gaming device

Fri Dec 22, 2017 3:45 pm

I found out that the PowerBoost has a 2A internal switch, so it can produce a 2A output. Does that mean it will automatically output 2A if needed, or is that a manual thing?

JPrograms
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Re: Battery Options for handheld gaming device

Wed Jan 03, 2018 9:15 pm

Never mind about the last post.

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