I have just successfully put together a Pi 4 and a RP 7” Touchscreen into a Smarti Pi Touch 2 box. I installed RP OS (full).
And it’s brilliant!!!
It works perfectly using the RP power adapter,drawing around 1 to 1.5 amps.
Problem is when I power the unit from a battery pack (with the eBay seller claiming it would start a tractor - well almost) the screen now flickers. The little usb dongle thing says the battery pack is putting out a consistent 5 volts, and showing a current drain around the 1 to 1.5 amps.
As it’s perfectly fine with the RP adapter I can only assume the battery pack is at fault.
Has anyone else successfully powered this same setup from a battery pack, and if so what brand and from where?
firstly let me say welcome to the core forum.
we need a little more info pls make and models and or exact part numbers…the more we know the more we can be of assistance…
cable your using…
did you purchase from core if so you should have all the part numbers etc…
ok pls check all your cabling and connections…here is a core tut on hooking up rpi displays pls have a read/look…
it sounds to me more a cable connector without seeing it in motion could you share some pic`s of it pls…
if you could monitor the 5 volt from the rpi-4 gpio pin with a dmm if it falls below by more than point 1 of a volt this could be a problem… pin 2 is 5 volt rail…
Nice setup! Do you know the capacity of the battery that you’re using as well as its voltage and chemistry? It’d be a great help in letting us identify your issue.
Thanks for the welcome and the tips.
Brian, I read your comment regarding the cables and connections being a candidate, so I had a good look at the quite long thin power cable carrying between 1 - 1.5 amps, an asked myself if I actually remembered any of my basic electronics from 40 years ago about voltage drops at higher amp pulls. I didn’t bother to check the voltage at the pin you suggested (as I figure it was going to be dipping low), I instead decided that I should try a short fatter cable keeping Ohms law in mind. And you know, the short fat cable is working perfectly, no more flickering, so I think you were 100% on the money in suspecting my cabling. So thanks. Cables aint cables.
true…18 or 16 gauge we used more commonly and yes the voltage drop over a longer run at such voltages/currents can be quite dramatic and very easily over looked.thx.
And hopefully I have managed a couple of pictures of my set-up.
The battery pack I am using is an unbranded eBay item with the usual amazing claims that should be dived by 2 and taken with a pinch of salt: 500000mAh LCD Portable External Battery Charger USB Power Bank Backup For Phone
The cable to now power the unit is the USB C cable that came with my Olympus EM-1 Mk2 camera.
I am now quite happy, onto the Command Line next.
Glad to hear it’s sorted out! Excellent call on the wiring Brian! That power supply should provide more than enough current for the whole rig if running properly. If you do run into any other issues with it I’d suggest switching that out for an official supply so that you’re ensuring the voltage and current requirements of the board and peripherals are met. Best of luck with the project!
d be dubious of any small sized lipo type batterys boasting 50Ahr like that though …my op and i`m guessing others…although it could but at what current drain is that rating at and what stable current by life span…??
500,000mah and 203g?! That seems ludicrously overrated for the size, I’d say that claim on ebay is a bit false! A 50ah single cell lipo would be big. 500ah, that would be uuuge! Only rated for 2.4A too… I think thats a discharge rating of 0.005C
Might be worth staying away from cheap Ebay Lipos, they scare me personally! But in any case I honestly wouldn’t put the problem past just being the battery just not being decent and being able to hold it’s voltage under load too However sounds like the cabling suggestion was on the money.