The temp sensor is in the pad itself, so even if it wasn't well attached it to the bed, the pad should have been able to reach/read 100c or more.

...assuming it was evenly adhered. If the area with the sensor had good thermal contact, but not the parts around it, it would cause that problem. Anyhow, I'm back to printing again.

SD sent me a new heat pad for the bed, and I can again get to 100C (13 minutes from 22C).
In retrospect, I think the old pad was not well bonded to the bed, because it came off very easily.
(5 1/2 weeks support turn around time on that.)

Same here. It took more than a month from when I reported it (with photos of the damage in my case) before I got the replacement. The temp sensor is in the pad itself, so even if it wasn't well attached it to the bed, the pad should have been able to reach/read 100c or more.

Glad to hear it's working.

Mine wasn't visibly loose, but it peeled off too easily and mostly cleanly. Perhaps the bed wasn't properly cleaned before the pad was installed.

I have some ceramic wool to try under it. I hesitated on a using ceiling tile because I wasn't sure if the binder would slowly char. Did you need to tweak the heater feedback settings?

Now I can hit 105, and 100 cycles nicely.
Check under the bed....scary stuff!

Anyhow, 90W @ 24V works out to 6.4 ohms.

Anyone know the proper resistance for the heat bed (unplugged from the board)?
Or the normal supply voltage for it?

Depends on the machine.  Normal is 12 or 24 volts. Usually it is 12 for most machines.

Sounds like my bed is half dead then (for 100c it took 18 minutes). I filed a support request. Thanks.

Pick up a cheap IR thermometer and measure it in various spots. I visually separate mine into 9 sections and measure each section. That's how I know the middle is 10 degrees hotter than the edges.