How to power the Mini5P from external 5V (no SBC)?
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@zapta I do this on my Duet WiFi and plan to when I get round to building my next printer (toolchanger with a D3Mini + expansions).
Two things to be aware of. If you use expansion boards, they won't be powered until you turn on the 24v supply, so have to be reconfigured after. I guess you can just turn on the relay from config though, or do a macro that turns it on and configures the expansion boards.
Other thing is inrush currents from DC PSUs which can be several times the normal peak current. I welded my first relay shut with the inrush current after a few cycles when first setting up my printer. That was a cheap 10A relay. Now I use a pair of 30A relays on both the HV and LV side of the PSU and not had any problems
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@fcwilt said in How to power the Mini5P from external 5V (no SBC)?:
What sort of emergencies do you anticipate?
Mostly a heater power mosfet/ssr becoming permanently short.
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@zapta said in How to power the Mini5P from external 5V (no SBC)?:
@fcwilt said in How to power the Mini5P from external 5V (no SBC)?:
What sort of emergencies do you anticipate?
Mostly a heater power mosfet/ssr becoming permanently short.
I'm not sure what you can learn from the firmware if a device like that fails.
Perhaps install thermal cutouts on the heat generating devices which will protect you from any source of too much heat, not just device failures.
Frederick
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@fcwilt said in How to power the Mini5P from external 5V (no SBC)?:
I'm not sure what you can learn from the firmware if a device like that fails.
If it happens during printing, the firmware detects it (abnormal PID behavior) and shuts off PS ON. I have a similar setting in my current printer (HEVO) and I confirmed that it works.
I also have thermal fuse on the bed but not on the nozzle heater.
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@zapta said in How to power the Mini5P from external 5V (no SBC)?:
@fcwilt said in How to power the Mini5P from external 5V (no SBC)?:
I'm not sure what you can learn from the firmware if a device like that fails.
If it happens during printing, the firmware detects it (abnormal PID behavior) and shuts off PS ON. I have a similar setting in my current printer (HEVO) and I confirmed that it works.
I also have thermal fuse on the bed but not on the nozzle heater.
I know it does that but the firmware doesn't know the reason.
As long as you are happy with the result that is all that matters.
Frederick
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@fcwilt you're right you don't know the 'reason' but you at least know which heater it is, and can maybe see the temperature graph
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@zapta I have a Mini5 configured in exactly this way. Can't say that I actually use the relay much and I may change it because of that.
I have a good quality (meanwell) 5v psu and a 24V psu both wired to the same mains switch. The mains passed through the AC side of the 5v psu and goes to a NO High Trigger relay before the 24V psu to control VIN.
Out from the 5v psu I have power lines running to 5v_EXT_in on the Mini5.
Also Out on the 5v I have 2 +5v lines one running to DC+ and IN on the DC side of the relay.
Then a single wire runs from the pson pin on the Mini5 to DC- on the relay.
24v VIN is wired normally after the relay.
In config.g very near the top I have a M80 to close the relay and apply 24V when the 5v power is applied. I can then turn off 24v from the duet as desired.
Hope that makes sense. Please be sure of what you are doing before hooking stuff up.
Also note that all of this is using the same ground. If you mix a ground in from another source bad things will probably happen.
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@nurgelrot, I think your system is exactly what I would to have here.
- What relay are you using? I got Digikey CCM1871-ND. It's a 30A relay (used with a flyback diode).
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I understand that all the AC grounds should be connected and all the DC (-) should be connected but am still debating if to connect the grounds and the (-). In my current printer the DC is floating.
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My frame is well grounded (in a few places, with anodize removed) but the X/Y rails of the gantry are not (this is a Voron 2.4, the gantry also moves on the Z axis). I may ground it as well.
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I also install a wall socket with a GFCI interrupter so any AC leak to ground will cut power immediately.
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@zapta Mine is just a generic 10A https://www.amazon.com/HiLetgo-Channel-optocoupler-Support-Trigger/dp/B00LW15A4W/ref=sr_1_6?dchild=1&keywords=relay+switch&qid=1629233141&sr=8-6 Seems to be fine for this application.
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@nurgelrot, I picked a 30A relay for a concern regarding the inrush current of the UHP-200-24 power supply (40A@110VAC, 80A@220VAC).
Got this din rail mounted 12VDC relay and replace with a similar one for 5VDC relay.
https://www.amazon.com/gp/product/B00UA46BFE
Was not sure how the relay continuous current rating applies to momentay inrush current.
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@fcwilt said in How to power the Mini5P from external 5V (no SBC)?:
In the years I have been building and using 3D printers I have never encountered a need for this sort of setup.
Around here our homes are built of dry wood. May require more fire awareness than those bricks dwellers.
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@zapta said in How to power the Mini5P from external 5V (no SBC)?:
@fcwilt said in How to power the Mini5P from external 5V (no SBC)?:
In the years I have been building and using 3D printers I have never encountered a need for this sort of setup.
Around here our homes are built of dry wood. May require more fire awareness than those bricks dwellers.
I don't leave my printers while they are printing.
Little things can happen that need attention - such as a filament break - or loss of bed adhesion leading to quite a mess.
Frederick
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@zapta said in How to power the Mini5P from external 5V (no SBC)?:
(40A@110VAC
That's like 4500 watts... If I had something hooked up that could draw 40amps over a 110 line I'd be worried about fire too... and 80@220??? you sure you're not arc welding instead of 3d printing?
