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13.8 volt power supply

Posted by daufhammer 
13.8 volt power supply
May 14, 2012 08:02PM
I am currently using an ATX power supply for my 12 volt power, but it can only put out about 6A on the 12v line, and im thinking of moving up to a heated bed, so i need a bigger power supply.

I have a 13.8 volt 12amp switching power supply (from my old R/C days) that I thought of using, but just wanted to make sure there wouldn't be any problems running things at 13.8 volts.... That's pretty close to 12 volts, and i know things like the power resistor in the hot end and heated bed will draw more current at a higher voltage, but since it's PWM'ed that shouldn't be a problem right? (As long as the resistor and heated bed are current limits are rated high enough). Things will just heat up quicker i imagine.

I imagine that the motors would run fine at 13.8v too since we use Pololu's which are current limiting stepper drivers, and i know some people run them at 24v.

Anyone see any problems with using my 13.8v 12amp power supply?
Re: 13.8 volt power supply
May 14, 2012 09:55PM
The normal advice for running with a higher voltage is to remove D1 to prevent RAMPS power feeding to the Arduino Mega. The regulator on the Mega isn't very well cooled so it can't take high voltages, I don't know if 13.8V would be enough to damage it. I'd just remove D1.The only real downside is that you won't be able to run the printer standalone without providing an alternate 5V source, in normal use it'll be powered by the USB connection.

Everything on the RAMPS itself is fine with higher voltages.
Re: 13.8 volt power supply
May 14, 2012 10:12PM
Thanks that makes sense, im actually using the older Pololu Electronics and after comparing the RAMPS schematic to the Pololu Electronics Schematic i don't think D1, which connects AM-VIN to the 12V source, exists for my setup. It doesn't even look like AM-VIN is even connected to anything for my Pololu Electronics, so I think I am good to go right?
Re: 13.8 volt power supply
April 13, 2013 11:17PM
It works normal.
you can conect 3 diode 13,8-(0,6*3)=12 volt
Re: 13.8 volt power supply
April 14, 2013 05:21PM
hmm i may turn up the voltage on my regulated psu to 15 from 12 if the board doesnt need any mods to run that way, i just plug the usb from the arduino into a phone charger anyways.
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