There has been some confusing info about the resistance and power consumption of this heated bed.
I hope I can clarify some of this confusion with this post.
There are two heating resistors on the heated bed. The heating resistors are made up of two copper tracks each about 1,3ohm. When the HB is configured for 12V operation (PIN 2 and 3 connected together) these two resistors are connected in parallel resulting in one 0,65ohm resistor.
When the HB is connected for 24V, these two resistors are placed in series, resulting a total resistance of 2.6 ohm.
So, when configured for 12V and connected to a 12V power supply you get:
P (power) = U² / R = 12² / 0,65 = 222W
I (current) = U / R = 12 / 0,65 = 18.5 A
When configured for 24V and connected to 24V power supply you get:
P (power) = U² / R = 24² / 2,6 = 222W
I (current) = U / R = 24 / 2,6 = 9.2 A
So it does not matter if you use a 12V or a 24V supply, when properly connected the power is 222W. But the current for the 12V solution is double, so the power expander and wires must be able to handle this current.
To heat up faster, you need to increase the power consumption. The only way to do this is to increase the supplied voltage (you can’t change the resistance of the copper tracks). e.g. you could supply 15V when the HB is configured for 12V (30V with the HB configured for 24V would be the same).
P = U² / R = 15² / 0,65 = 346 W
I (current) = U / R = 15 / 0,65 = 21.5 A
This can be combined with the power supply for the printer if the supply is powerful enough. 350W for the bed plus 150W for the printer = 500W
I found a cheap 15V / 400W PSU. No enough to use for both HB and printer. So I will install this power supply in addition to the original Vertex PSU.
As power expander I found this :