Heating failed, Heatbed

Tim92Tim92 Posts: 12Member
Hi,
I own a new A5 printer since 4 days.
The first few prints worked fine.
Since yesterday I got the Error: Heating failed, system stopped! Heater_ID: bed

It only happen if I want to print ABS with 110C bed temperature, the day before it worked fine.
The error occurs after some minutes and the bed reached 100-104C.
My ntc of the bed is about 90k at room temperature. My power supply is set to 24,50V
I use the community firmware.

Any ideas?
Post edited by Tim92 on

Comments

  • Samuel PinchesSamuel Pinches Posts: 2,917Administrator
    edited September 2018
    Hi @Tim92  - and welcome!

    Unfortunately, the power supply in the A5 is not able to output enough power to reach 110C. Most can reach 105C-108C. You could try and cheat, by increasing the 24.5V to the maximum setting... the fans will be ok with a little more voltage, and this may enable you to reach 110C reliably. There is normally a small potentiometer on the power supply that can be turned to adjust the output voltage a little. A small increase (26v - 27V) may be sufficient.

    The other options are to put your printer in an enclosure, or add cork insulation to the underside of the heating element.
    Post edited by Samuel Pinches on
  • Tim92Tim92 Posts: 12Member
    The maximum I can reach is 24,7V
    Any cheap power supply which is better?

  • Samuel PinchesSamuel Pinches Posts: 2,917Administrator
    edited September 2018
    Unfortunately, cheap or quality ... choose one. 


    Quality: https://www.ebay.de/itm/173441939533

    And then the power supply will be larger too, so you may have to use it externally.

    There is a big jump in price and power, from 24V, 360W (stock) ---> 24V 480W.

    May I ask, do you need 110C for ABS?
    Post edited by Samuel Pinches on
  • Tim92Tim92 Posts: 12Member
    I tested it with 100C and the parts every time curl up on the edges.
    With 110C there are no problems without build plate adhesion.
    its strange that it worked yesterday, I only added a led strip to the power supply, but I tested it today without the strip with the same problem
  • Samuel PinchesSamuel Pinches Posts: 2,917Administrator
    I've sent you a private message.
  • Tim92Tim92 Posts: 12Member
    edited September 2018
    I upgraded my power supply to 480W but still get the error.
    I replaced the ntc of the heatbed too. Any other options beside the firmware changes?

    I changed the firmware, but with the new power supply its not possible to reach 105C anymore.
    But I also installed a raspberry pi on the same supply
    Post edited by Tim92 on
  • Samuel PinchesSamuel Pinches Posts: 2,917Administrator
    edited September 2018
    Upgrading the power supply should definitely reduce the heating up time, but it may NOT fix the max temperature:

    Power = Voltage * Current
    Voltage = Current * Resistance
    therefore Current = Voltage ÷ Resistance
    hence, Power = Voltage * Voltage ÷ Resistance.
    Since Voltage is fixed 24V, and Resistance of the bed is unchanged, then there is no way to increase the power to the bed further.

    The exception is where the original power supply was insufficient, and unable to maintain 24V when the bed is on. 

    However, it definitely shouldn't lower the max temperature. Maybe the 480W is not correctly rated? Can you perhaps measure your printer power consumption with a AC power meter? Try tweaking the output voltage again?

    Maybe adding cork insulation to the underside is something to try?
    Post edited by Samuel Pinches on
  • Tim92Tim92 Posts: 12Member
    I tested it with 26V and 110C work fine, is there any problem with the other hardware with 25-27V?
    I'll also test the cork insulation
  • Samuel PinchesSamuel Pinches Posts: 2,917Administrator
    Great! 
    No, all the high voltage parts should be fine up to 30-32V generally.
    The 5V parts must be used only at close to 5V, but the 24V parts are generally more tolerant.
  • Tim92Tim92 Posts: 12Member
    Ok perfect, I ordered cork today to save a little energy.
    Now I'm pretty satisfied about this printer. The price is awesome for the quality.
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