Power Issue with Octopi
I have a bit of a unique situation that I am hoping someone here can help me out with. My MK4 with MMU3 is on a sailboat. I have it setup to be powered from either 110v AC or from a DC to DC converter that converts my 12v system to the 24v needed by the printer. The DC to DC converter is rated at 20amps continuous with 30amps max... which is more than enough to run the printer. Also, I have a Pi running Octoprint.
When running the printer from the 110V AC, no issues. However, when running the printer from the DC (like when I am out sailing... which I have done and think that's pretty cool) the Octoprint gives me low-voltage warnings. I have even noticed that if I unplug the DC Positive the printer will still stay on with the Pi plugged into the USB-C port on the MK4 board. Starting a print this way pulls too much power and the Pi shuts down, and printer crashes. If I reboot the Pi, I get no power warning until I start a print, and then I believe the heat-bed and nozzle heating draw enough that it saps some of the Pi's power.
I thought the port for the Pi on the MK4 board did not pull any power, but it does appear to, at least enough to draw the Pi's power down for a warning. The Pi's USB is on a completely different circuit to the printer. The boat's electrical system is powerful enough to run the AC if needed (4 330ah lithiums with 3000watt inverter/charger system, all by Victron which is probably the best equipment in the marine electrical business).
Any ideas? Thanks in advance for any help anybody can give.
RE: Power Issue with Octopi
Grounds and bonding can raise issues on a boat. Is the USB cable the only common ground between the printer and the pi?
RE: Power Issue with Octopi
Thanks for the reply...
All the grounds end up connected, and the boat does have a big grounding plate on the hull which was needed for the SSB to work correctly. Grounding through the USB to the Pi, to the USB outlet, to the boat seems like a much tougher route than from the printer to the DC-DC converter (that shares the ground) to the rest of the boat.
Maybe it just something I have to live with.
RE: Power Issue with Octopi
If it is just the Pi that is causing problems you could run it off a power bank to isolate it from the boat electrics
How well regulated is the DC? Try to get a trace recording - I remember a system that ran an echo-sounder cable in the same trunking as the AIS. Not only could you hear the pulses on VHS from adjacent vessels as the AIS aerial radiated the inducted pulses but they got louder and the plotter kept dropping out in deep water as the extra load repeatedly took VCC below it's working level.
You might find a biggish capacitor enough to stabilise smaller fluctuations.
A Pi needs 5.2V for stable operation, this is higher than many USB ports can provide; USB chargers usually supply enough.
Cheerio,
RE: Power Issue with Octopi
Thanks...
Fortunately I've removed all the old electronics from the boat and everything is NMEA 2000, and the newer depth sounders are pretty good about not interfering. Most of the time the AIS and the VHF share an antenna, so what affects one, won't affect the other.
The DC is pretty on point, being Victron equipment I can monitor everything pretty closely and I don't see any voltage drops on the system at all. And this problem occurs during the day or night when I am collecting solar or not, meaning the battery voltages in charge cycle or discharge don't seem to affect it.
The Pi is plugged into a USB C outlet, but not on a charger block... as that outlet is plugged into the 12V system.
I appreciate all the ideas about power delivery, as that does seem like an obvious issue (although nothing else has a problem), but I can't escape the idea that the MK4 is drawing power from the USB C port when it shouldn't be.
What voltage are you getting from the usb port?
What have you got plugged into the Pi's usb?
Cheerio,
RE: Power Issue with Octopi
I'm buying a device to check voltage and amperage from the USB C (I have one for USB A), and nothing else is plugged into the USB ports. I will probably swap out the port too, in case that's part of the problem.
RE: Power Issue with Octopi
a device to check voltage and amperage from the USB C
I've got one, I find no power from the USBC connector on my early-model MK4.
Looking at the schematic for the MK4 xBuddy board, there's a solder-jumper J1 between the USBC and power. Here's a link to the MK4 schematics, see sheet /USB/ of the file FDM-xBUDDY-44.pdf .
RE: Power Issue with Octopi
I have an inline USB C power tester that has shown me my issue. I have some more testing to do, but it appears the Pi is only getting 4.8v without the printer running, and then drops down to 4.5v when the printer is running. I'm going to run all new wire from the breakers to the Pi and see if that helps, and use a dedicated buck converter for it so the voltage is consistent.
Thanks for everyone's help... I'll update when I get this done in case anybody else is hoping to do something similar.