SOLVED Optimising M911 power recovery

  • I've just started playing with power recovery.
    Duet 2 Wifi
    24v PSU
    240v Heat bed
    Reprap v3.1

    I've added a 50000uf 50v capacitor across two of the PSU output terminals and have
    M911 S22.0 R23.0 P"M913 X0 Y0 G91 M83 G1 Z3 E-2 F1000"
    to config.g

    Whilst I am able to recover from a simulated power outage, there doesn't seem to be enough power in the system to raise the hotend. This results in a lump of plastic stuck to the part as the nozzle oozes a little while cooling.

    I know the firmware turns off the heaters on power outage, but does it also turn off all fans?
    I have three 24v fans in play.
    Hotend (Thermostatic)
    MCU (Thermostatic)
    Part cooling (manual, but not actually in use during test)

    Is there any value in adding commands to shut all these off in M911?

  • Still interested in the answer but just realised I had an led strip running that would have drained the cap very quickly
    I'll try again with it off.

  • administrators

    If that LED strip is controlled by a fan or heater output, you can include the command to turn it off in the power fail script.

    The firmware does not automatically turn off fans in response to a power failure.

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