Anyone powering Pi 4 from Pegasus box

[Richie092]

I’m currently powering my Pi4 from a 3 pin power supply but once my Pegasus power box (finally) arrives I will want to power it via a USB port but apparently you can’t. 
 

anyone got round this?

[MarkAR]

If you have the UPB V2 then the variable power output can be set to the necessary 5.1v for the RPi. 

Well I hope it can as that's the route I will want to go in the future when I get a Pi.

Or if you don't have the V2 then I think you could feasibly use one of the 12v outputs stepped down to 5v.

[Richie092]

It is the V2 the problem is going to be cable I think. I just tried to buy one and after a bit of research have discovered an issue with the RPi 4 that it doesn’t like peer from a USB cable. Something to do with incorrect architecture. 
 

checked Pi hut for a lead and they aren’t advertising one so may need a work around. 

[vineyard]

11 minutes ago, MarkAR said:

If you have the UPB V2 then the variable power output can be set to the necessary 5.1v for the RPi. 

Well I hope it can as that's the route I will want to go in the future when I get a Pi.

Or if you don't have the V2 then I think you could feasibly use one of the 12v outputs stepped down to 5v.

I think USB port 6 on the v1 UPB provides 5V/3A "always on" so no need for a step-down.  (At least that's what I hope - am switching to that!).

[MarkAR]

Well if port6 can provide the correct output then there is no reason it shouldn't work but as Richis says, it may not like it.

My bets on the variable output port which supposedly is for mini computers.

[Richie092]

Sorry, missed these replies.

UPBV2 Still not in stock so no testing done yet. I am going to try it with the USB type C cable that came with my ZWO 120 when it arrives. It isn't the power supply that is the problem but the type of lead the RPi 4 will take power from. It wont accept power from any of my apple cables for instance.

Last piece of the puzzle then I will be happy with my setup.

 

[MarkAR]

I've been hacking the net for possible solutions and can only really come up with making a DIY USB-C to Pegasus jack plug. Looks like you just solder on Ground and 5v.

 

[TerryMcK]

When I'm not using the Pi4 for actual imaging (when doing a few test scenarios for example) I just plug it into a spare USB socket on a computer. Never had any issues. So I can't see why you can't power it from the Pegasus.

Edited July 13, 2020 by TerryMcK

[Richie092]

MarkAR - yes, that would bypass whatever it is in most USB cables that stops them working properly with the RPi

Terry McK - from what I can gather, most USB cables allow a max of 2,5 amps whereas the RPi needs min 3 amps. Just what I have read, as yet I don't has a USB - c cable in the house that powers it.

[MarkAR]

Excellent, that sound like it'll work then.

Also sounds like one of these from the USB port will work as well.

https://www.amazon.co.uk/TecMad-usb3-0-Braided-MacBook-Devices/dp/B0756WJPZQ/ref=sr_1_10?dchild=1&keywords=usb-c+male+to+usb3.0+male+cable+short&qid=1594656663&s=electronics&sr=1-10

[Richie092]

ordered one, will let you know. 🙂

 

[Corncrake]

9 hours ago, Richie092 said:

isn't the power supply that is the problem but the type of lead the RPi 4 will take power from. It wont accept power from any of my apple cables for instance.

I dont know if this will help or not as I dont know the Pegasus but for what its worth :-
It was only the early RPi4 that had a problem with the fast charge cables.
It did not implement the USB spec. correctly ie. it did not have the correct configuration of resistors on the usb power input to tell the high capacity source to deliver high current. But a standard cable from a regular USB port capable of delivering the RPi current will be ok.

 later models (revision 1.2 ? I think) corrected all that.

Edited to make better sense of what I was trying to say !

Edited July 13, 2020 by Corncrake

[Richie092]

OK I must have an early one. What you have just described is what I ineptly have been trying to say for the whole thread 🙂

When the Pegasus turns up I am going to try with the cables I have and if I have no luck I may just buy a later 8gb version now Stellarmate supports 8gb.

 

 

[SiD the Turtle]

Just bumped into this thread as I'm looking at buying the Pegasus Powerbox Advance. Indeed is it 'just' the early model Pi 4s?

Mine are new-ish and I am running Astroberry and an ZWO guide cam off of a random Anker power bank that I used to use as an emergency mobile phone charger. That outputs at 2.4A if I am correct, and it's stable with no issues in the last few months I've been using it.

Sorry if that doesn't help you if you have an older revision.

[Avocette]

On 13/07/2020 at 16:34, Richie092 said:

from what I can gather, most USB cables allow a max of 2,5 amps whereas the RPi needs min 3 amps.

This seems to have become one of the ‘myths’ that are more difficult to stamp out on forums. The RPi4 doesn’t ‘need a minimum of 3 Amps’. The RPi4 typically runs on a lot less - but if you load all the USB sockets to their maximum with heavy consuming devices or those with high startup current demands. My setup needs 6 USB connections so I use a T-link 7 port USB hub. This is powered in my case by 12V from my Pegasus Pocket Powerbox. Three of its USB hub ports are ‘charging’ outputs each delivering potentially 1.5A. In my case one of these is used to power the RPi4 via a 20cm USB Type A to USB-C cable. 

Edited July 19, 2020 by Avocette
Corrected 1.5A and not 2.1A

[Avocette]

I just had the chance to measure the current drawn by my Raspberry Pi 4 4GB running Astroberry in my normal configuration. I used a cheap 'CHARGER Doctor' so measurement accuracy is probably not to +/- one least significant digit, neverless here are the figures: Voltage 5.07V, Current when Astroberry is in Hotspot mode but otherwise no application programs are running around 0.42A and when KStars/Ekos/Indi are in operation and the mount tracking current reads 0.51A. My RPi4 boots directly from a SanDisk SSD plugged into a USB3.0 port on the RPi4, and the T-link 7port USB hub is fed from the other RPi4 USB3.0 port. The USB2.0 ports on the RPi4 are not used. The final photo shows the short USB Type A to USB-C power cable.