Little bit new to using raspberry pi (used to Arduino) - I’m trying to create a portable setup for raspberry pi with speakers and display screen. I’ve thought about using these:
My main concern is whether the hat, bonnet and display will fit together, and whether there is ample power for all devices to work off of from a portable setup. Any suggestions would be greatly appreciated.
Hey there, @Keegan254705, and welcome to the forum, glad to have you here.
You can definitely stack those HATs together long as you have some Extra-Long Stacking Headers. You may have some issues if the individual HATs use dedicated GPIOs that overlap with the other HATs, but you should be able to change that in the software.
That UPS HAT, however, only supplies 2A to the Pi. The Display bills itself as low power, but I can’t see any official documentation on exactly how much power it uses, which makes it hard to say for certain if it would work. Otherwise, there are other UPS HATs that can supply more power.
That HAT would do the trick! I did some digging and was able to find a comment on the product wiki for the display from the manufacturer that states it will draw 1.2W (0.24A at 5V). The Pi 3B will need at most 2.5A, so your total current draw for the setup should be around 3A. The HAT you linked with 6A will be able to provide this easily.
As for the power consumption of this display, you won’t really find many displays that have a similar picture quality with a lower power draw. I would stick with this display. As long as your UPS HAT can provide over 3A you should be good to go!
That may be but nobody that I can see has mentioned the fact that the primary source (battery or whatever) has to supply this power (5 * 6 = 30W) plus any conversion factors involved.
Like 30W @ 5V = 6A. 30W @ 3.7V = 8.11A if your source is 3.7V battery. Add the conversion factor which could be 85% this required current could be 9.54A.
If all this is not considered the result at the end of the day could be somewhat disappointing and expensive.
Cheers Bob
Hi Keegan
Sorry but I could have been more explicit.
I just looked at the link to the Geekworm product. Those numbers I quoted are WORST CASE. That is asking the hat to provide the full 6A. I was also using (in the example) the nominal battery voltage of 3.7V as this voltage will drop to this fairly rapidly from full charge (4.2V). I also used 85% conversion loss which may well be anything up to 95%, depends on design I suppose but there WILL be some loss. Maybe if one looked a bit further down this figure might be quoted.
Does not matter. The method I used to arrive at the actual required current from the source still applies. Just have to change the numbers. In this case the source would be 2 X 18650 cells in parallel.
I also note Specifications
Power supply via Type-C socket : 5Vdc ±5%, ≥3A, Via DC power jack : 5Vdc ±5%, ≥4A
UPS output : 5.1V ±5% Max 6A
UPS charging current: 2.3~3.2A
Terminal Battery Voltage : 4.24V
Recharge Threshold : 4.1V
That 4.1V looks a bit strange. Depending on current requirements that would probably only get a few minutes as the drop from 4.2V is only 0.1V.
Be aware that both of these links sau this is a “UPS” (Uninterruptible Power Supply) device. Designed to keep a system alive long enough for a controlled shut down. UPS does NOT mean a power supply for longer term use. Whether this can be used as such depends on what happens when the device drops to 4.1V. It might shut down which means it will not be much use for longer times.
Sorry but I am afraid these are facts of life.
Cheers Bob
The “specifications” are from the Geekworm product sheet.
All the links I saw are for “UPS” NOT “Portable power supply”
