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I need to know the maximum input for current, voltage and power for:

  • RAMPS 1.4
  • RAMPS 1.5
  • RAMPS 1.6

I want to build a DIY 3D printer. RAMPS 1.6 can deliver only 270 W. but if I total my heatbed + hotend + other components, it will be 300 W which exceeds the amount of RAMPS 1.6 output.

I have 24 V 24.5 A power supply. Is it okay if I connect it to RAMPS 1.6?

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    $\begingroup$ I guess the heated bed is the main power consumer here, if this is drawing more than 10 A you definitely need to insert an external MOSFET, these are cheap external modules that can handle even larger currents than the board itself. Found easily on those typical online market places. $\endgroup$
    – 0scar ♦
    Commented Feb 13, 2022 at 7:08
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    $\begingroup$ P.S. RAMPS shields on top of AtMega Arduino boards are pretty outdated, they will work, but there are plenty of other boards available to choose from. You should look into 32-bit microprocessor boards. $\endgroup$
    – 0scar ♦
    Commented Feb 14, 2022 at 6:13
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    $\begingroup$ Furthermore, this question should be reworded, instead of focusing on the RAMPS 1.x board differences, you should focus on the real question where you are interested in: "How to get more power from a board than they are rated for?" or "The current required for my printer exceed the current ratings of my controller board, how can I mitigate this?". $\endgroup$
    – 0scar ♦
    Commented Feb 14, 2022 at 14:27
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    $\begingroup$ And change the title to reflect that fact... $\endgroup$
    – Greenonline ♦
    Commented Feb 14, 2022 at 15:36
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    $\begingroup$ @Navin - good catch, that should probably be "maximum output". I hadn't noticed that. $\endgroup$
    – Greenonline ♦
    Commented Mar 7, 2022 at 15:26

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RAMPS power consumption

The power consumption for all three versions of the board should be, essentially, the same.

RAMPS 1.4

The info is on the RepRapWiki - RAMPS 1.4 - Power supply:

The board has two pairs of connectors for power, one labeled 11A and the other 5A, both of these pairs are 12V connections.

and

Your power supply should be able to deliver 16 amps, is ok if it delivers more.

and

Other variants are the S-480 and S-600 for 480W and 600W respectively.

So, $I = 16 A$, $V = 12 V$

You can then calculate the power from $$P = IV$$

$$P = 16 x 12$$

$$P = 192 W$$

Alternatively, considering each circuit in isolation:

  • $I_1=11 A$ for the heated bed only;
  • $I_2=5 A$ for the stepper motors, hotend, etc.

$$P_1 = I_1V$$ $$P_1 = 11 x 12$$ $$P_1 = 132 W$$

and

$$P_2 = I_2V$$ $$P_2 = 5 x 12$$ $$P_2 = 60 W$$

so the overall power consumption,

$$P_T = P_1 + P2$$ $$P_T = 132+60$$ $$P_T = 192W$$

Important note: While the overall power may indeed be 192 W, it is important that you only draw the maximum individually rated current/power (5 A and 11 A) from each of the respective circuits - you can not draw 16 A (192 W) from just one of the circuits alone. To attempt to do so would be dangerous and may result in a fire or worse.

RAMPS 1.5

From RepRapWiki - RAMPS 1.5

The layout of the RAMPS 1.5 is virtually identical to that of the RAMPS 1.4. The only real difference between the two are the MOSFETs and the fuses.

Only the form and type of the fuses are different, not their ratings. Therefore, the voltage and current specifications would appear to be the same as RAMPS 1.4

RAMPS 1.6

From RepRapWiki - RAMPS 1.6

It maintains the surface-mounted fuses and flush MOSFETS of the RAMPS 1.5.

Therefore, the voltage and current specifications would appear to be the same as RAMPS 1.4

Note that there are other variants of the RAMPS board that you may need to consider, such as the 24 V version and so forth.

Supplying additional current and/or power

Using an External MOSFET

To draw more current than the RAMPS can supply for the various heating elements, you could use an externally switched circuit (whose MOSFETS are triggered by the RAMPS outputs), in place of the RAMPS outputs, to supply this additional current.

See Modify RAMPS 1.4 adding external MOSFET for heat bed: can I remove original mosfet? which links to the excellent Howto Connect your Hotbed (and or extruder) to a Mosfet:

External MOSFET schematic

External MOSFET schematic

Apply a second PSU ( 12 or 24 volts)

Apply a second PSU ( 12 or 24 volts)

Apply a second MOSFET (for the extruder)

Apply a second MOSFET (for the extruder)

See also MOSFET Band Aid in 0scar's answer to Which 3D printer controller should I use?:

MOSFET External module

Power consumption rethink

Alternatively, and probably better, rethink your power consumption, so that it matches that which can be supplied by the RAMPS board. Your current draw, and hence power requirement, shouldn't need to be so high.

24 V capable RAMPS

Another alternative is to get a RAMPS which can handle 24 V, which, whilst not supplying more current, will provide you with more power (approximately twice as much). However, this may require that you get a different set of heating elements (if your current set isn't dual voltage capable) - which obviously isn't ideal and will entail even more expense. See Do I have to buy all new components if I were to get a RAMPS 1.4 that supports 24 V power?

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