<p>My voltage at the controller at max load is ~11.4&nbsp;V 
(heated bed + motors + hotend). Is this normal? </p>

<p>I'm measuring 11.8&nbsp;V at the PSU, so 0.4&nbsp;V -> 5&nbsp;W lost in the wires.</p>

<p>I have a pretty beefy ~2&nbsp;mm diameter copper wire that's ~1&nbsp;m long. Its area is 2.5&nbsp;mm<sup>2</sup>. The diameter with shielding is 3.5&nbsp;mm.</p>

<p>Could there be a bad connection somewhere?</p>

<p>Checked the wire is warm to touch, so looks like it's actually the cause.
Is this normal? Should I go for even bigger wires?</p>

[{'answer_id': 9886, 'author': 'Viesturs', 'author_id': 16405, 'author_profile': 'https://3dprinting.stackexchange.com/users/16405', 'pm_score': 0, 'selected': False, 'text': '<p>Per <a href="https://www.calculator.net/voltage-drop-calculator.html?material=copper&amp;wiresize=6.571&amp;voltage=12&amp;phase=dc&amp;noofconductor=1&amp;distance=6&amp;distanceunit=feet&amp;amperes=18&amp;x=34&amp;y=15" rel="nofollow noreferrer">this website</a> it matches the expectations.\nUsing 13AWG =~ 2.5 mm^2, 18amps, 12volts, 6feet = 2meters (1m back and forth).</p>\n\n<p>Results in 0.4v drop.</p>\n'}, {'answer_id': 9896, 'author': 'cmm', 'author_id': 2082, 'author_profile': 'https://3dprinting.stackexchange.com/users/2082', 'pm_score': 2, 'selected': False, 'text': '<p>Regardless of how the voltage is lowered, you aren\'t delivering the power to the heating elements that they are designed to deliver.  For a resistive heater, the power scales with the square of the voltage.</p>\n\n<p>Delivering 11.4&nbsp;V to the heaters will result in the power being <span class="math-container">$11.4^2/12.0^2 = 0.9025$</span> or 90&nbsp;% of the intended power.</p>\n\n<p>There are two things you could do to increase the power at the heaters.</p>\n\n<ol>\n<li>Your voltage is starting out low, which you may be able to increase\nat the power supply to 12.0&nbsp;V.</li>\n<li>The voltage drop in the 1-meter cables can be reduced by using\nshorter cables or larger cross-sectional area conductors.  13 gauge\nis not a very heavy wire for low-voltage high-current DC.  I would\nsuggest 10 gauge, and would prefer 8 gauge.</li>\n</ol>\n\n<p>The logic in the controller board should be fine as you are now.  Controller boards include regulators that being the nominal 12&nbsp;V down to the 5&nbsp;V or 3.3&nbsp;V required by the digital logic.  These will automatically adjust for changes in the 12&nbsp;V supply.</p>\n\n<p>To actually answer your question, the permitted voltage drop is application dependent.  As a rule, though, I would suggest that the voltage on the pins of the controller should be 12&nbsp;&plusmn;&nbsp;5&nbsp;%, or from 12.6&nbsp;V to 11.4&nbsp;V.  The voltage you measured should be acceptable if it is the true minimum voltage.</p>\n'}]
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