What power input is required for the RAMPS 1.4 electronics?

This is a question I answered on the now defunct makers stackexchange QandA site:


This is a companion discussion topic for the original entry at http://reprage.com/post/26484690567/what-power-input-is-required-for-the-ramps-1-4

what if i am running three steppers at 2A each, 2 hot ends, and a heated bed? will 5 amps be enough? can the board run at higher? the 3 stepper are for y, e0 and e1. the x and z steppers will be run by external drivers with a separate psu)

thanks you in advance

The heated bed will need to run on the separate 11A input. So that should be OK (as long as your power supply can handle it).

As for the three steppers and 2 hot ends, it looks like you will be drawing 6 amps on steppers, plus change in hot ends. For me, my hot end draws about 2 amps. (but the steppers much less). See:

So at a rough guess it looks like you are going to need input of at around 10amps for your beefed up hardware. You will need a power supply capable of this. As for if the RAMPS board can handle this? My guess is that you are going to struggle getting 10 amps past the stock MFR500 fuse. The smaller yellow component, installed at f1 here:

You could try replacing it with another larger yellow fuse used on the 11amp circuit (f2). But I have no idea if the traces on the board are able to handle the kind of current you are going to be pushing down it. So in short, you are going to struggle.

Hi reprage,

thank you very much for the prompts response. after reviewing your advice, my head is just more confused as to how the ramps 1.4 is capable of handling 5 steppers with the possibility of 2 extruders. if 5A is the max, and the hot ends takes at least 2A, then 4A are taken by 2 hot ends right away. that only leaves an amp for everything else…which doesn’t add up.

could you please explain?

thank you

I have never run a dual extruder setup.

But I do know my steppers hardly draw much. The total current dumped into your steppers is controlled by the pot on the pololu, and if you take another look at that power usage post – my setup is configured such that the steppers barely pull anything at all.

That being said, I have had problems with the RAMPS fuses, and do use a fan to keep the whole board cool. So i’m guessing, total power usage of a high power dual extruder setup such as yours may have been overlooked in the original design.

i guess that makes sense, seeing as how it is sort of the board that started it all. May i ask what torque/amp motors you are using for you axis and extruders? i am planning a bowden setup, so am i correct in assuming that i need at least 62ozin for the extruders (flexible material needs more torque i hear). also, may i ask where you sourced your motors from?

I use Wantai steppers, I really like them. The model number is 42BYGHW811 4800 g/cm. Running them no where near there rated 2.5 amps. Product sheet is here:

I get them straight from the manufacturer via ebay.

I do not have a heated print bed and the only power supply I have is well over 5 amps. So can I wire a higher number of amps into the 5 amp terminal and the ramps will only draw as many amps as it needs?

Yes, the printer will only draw as many amps as it needs. My the 5A ‘channel’ on my ramps board is wired to an 8A input.

ok, but say I wanted to power my 3d printer using a lipo battery that can supply up to 50 amps would that be safe to do so?

Sorry for the delay. How did you go? Did the lipo battery work?

Yes the 3s Lipo worked. I was only using a 2200 mah so it didn’t last that long

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Nice. Got any photos? I would be keen to see that.

Is there a max current value ?? and why are can the fuses be damaged if current is under 16 amps and not higher?? please respond as quick as possible i need this for a research

Yes, the max current your printer will draw is 11 amps for the heated bed, and 5 amps for running the stepper motors / everything else. As per other comments here, your power supply can be rated higher, but your printer won’t use more than 16amps.

If your printer tries to use more than 16 amps, thermal fuses on the RAMPS board will trip and cut power to your printer. (After it cools down it will start again). If you don’t supply enough current (lower than 16 amps), your printer will suffer ‘brownouts’ and not function correctly.

Thanks for your reply reprage that really helped me out! Can you tell me more about the brownouts?

Haven’t experienced the brownouts myself. My guesses would be for the 11amp circuit, the heated build platform won’t get to temperature. For the 5 amp circuit I imagine the arduino

hi guys
i have a 3d printer with chinese mega 2560 and ramps 1.4 and
the hot end work correctly but any motors not work on it???
the marlin is new version
the steppr motors not in correct plug
the driver not fail
just the power supply i before used be 20 v 10 a but before my arduino mega original italy fail it works
but i reduce the voltage to 12 volt but motors not work
i checked everything
im not end stops on it
my pronterface message: echo:busy: processing
and motors not work
please help me
i become crazy…
thanks

Did you adjust the trimpot on the stepper drivers when you lowered the voltage? You might need to crank the drivers up a bit to compensate?