Creality 24v Heatbed

Does anyone know how long it should take for a Creality 24v heatbed to get hot? Seems like for me it's taking ~15min to get to 60c.

It should be at temp in a minute or so.

You could measure the resistance of the hotbed when disconnected from the controller box.
A 24 volt 240 watt hot bed should measure about 2.4 ohms and online watts laws calculator can be of help here.

You could also remove the case on the controller box to see if maybe one of the wires to hot bed, post photos if unsure.

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Computer Programmer / Electronics Technician

I think I found my answer. I think my bed is not way out of spec I suppose. I was reading around and found an article that references the heat up times.



"In comparison, the CR-10 heats up much more slowly than the Ender 3. Comparisons across the community show that the CR-10 heats up 80°C in about 20 minutes, while the Ender 3 can go high at 120 C in about 15 minutes. The difference can be accounted for the larger print bed of the CR-10, as well as its lower voltage."

That's extremely slow for 24v, even for a bigger heated bed. I never knew this. Maybe the Creality firmware has some kind of setting only allowing you to use a small portion of the amperage available to lower the strain on electronic parts?

Is the underside of the bed insulated?

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http://www.marinusdebeer.nl/

I did insulate the bottom. That didn't make any significantly faster. I suppose I was just trying to figure out if I got a bad one or not. I may have...

Ok, it's all related to how the PID settings I suspect. I disabled the PID Settings and it took a about 2:30 min to get to 70c, but it was not nearly as as stable when using the PID settings. The temp would go between 73 and 68 constantly. I ran the auto tune several times and when I use those settings, heat up time always takes forever to heat on the order of 15-20 min, but it's stable.

What am I doing wrong?

I'm running M303 E-1 S70 C8 for my autotune.

I finally gave up and just set the bed to use bang bang. It heats up fast and it works.