Second Power Supply for Heated Bed

Hi,

I am currently making a large 3d printer. I am using a Ramps 1.4 and ardunio to control it and it is powered using a 12v 20a led power supply giving it 300w. I am looking to put a heated bed onto the printer but the power supply will not handle it.

I am unsure how to power the heatbed and i am looking for some guidance. Could i use a larger atx power supply with the ramps board? could i use 2 power supplies, one to each input on the ramps board? Or finally could i use a power exander connected to the ramps board which would output 12v and a second 12/24 power supply powering the heat bed.

I am looking at two heat beds. Both are 300x300 silicon heat pad and one is 24v and the other 12v.

Thank you for any help or advice given.

You could use a Dc/Dc solidstate relais ( search SSR ), but they are expensive. Don't try cheap DC/AC SSRs unless you get a mains powered Silicon heater.

Also you can use ATX power supply or two separate supplies ( make sure you have a good GND connection between them )

Yes you can use 2 power sources.
I have a 12V for the board and a 20V for the heatbed.

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www.3daybreaker.blogspot.com

Orca V4.4 rebuild to Ramps with Mk8 and E3D, as well as a Rostock Delta Mini and an OLO in backorder :-)

Ramps has two separate DC-in plugs specifically for powering your heated bed separately. The one closest to the bottom edge of the board (by the reset) is for everything but you heated bed and has a 5a polyfuse. The jack on the side closest to the MOSFET's is for your heated bed and I believe has a 16a polyfuse. Yes you can power them with different PSU as long as everything has the same ground reference.

The GNDs on the ramps power plugs are joined.. you would have to be tiring to separate them

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Yes you can use 2 power sources.
I have a 12V for the board and a 20V for the heatbed.

What components did you use and how did you wire yours up? Thanks for responding

AFAIR the power input for the heatbed got a 11A polyfuse. If you need more, and you are somewhat firm with putting electronic things together, you could use a BTS555 - with a good cooling it will handle 165A at 40V, resulting in 7kW - probably enough, I'd say ;-)
Edit: Just looked at the datasheet, and the 40V or 44V isn't the nominal Vbb voltage, this is 34V, still resulting in 5610W. Anyway this thing will probably fire up any heated bed at 12V or 24V without problems.

Edited 2 time(s). Last edit at 02/21/2017 09:05AM by Inhumierer.