Reference boundary

Preliminary battery-cable voltage-drop arithmetic only. It does not choose fuse size, ampacity, thermal limits, or battery safety approvals.

Reference table

Estimate DC battery-cable voltage drop by current, one-way length, and copper conductor size.

Formula basis: DC voltage drop = 2 x current x length x resistivity / conductor area.
Copper sizeArea (mm2)V drop at 100 A, 1 m12 V percent24 V percent48 V percentScale note
10 AWG5.260.6565.462.731.37Scale linearly by current and one-way length
8 AWG8.370.4123.431.720.86Scale linearly by current and one-way length
6 AWG13.30.2592.161.080.54Scale linearly by current and one-way length
4 AWG21.20.1631.360.680.34Scale linearly by current and one-way length
2 AWG33.60.1030.860.430.21Scale linearly by current and one-way length
1/0 AWG53.50.0640.540.270.13Scale linearly by current and one-way length
2/0 AWG67.40.0510.430.210.11Scale linearly by current and one-way length
4/0 AWG107.20.0320.270.130.07Scale linearly by current and one-way length
250 kcmil126.70.0270.230.110.06Scale linearly by current and one-way length
350 kcmil177.30.0190.160.080.04Scale linearly by current and one-way length
500 kcmil253.40.0140.110.060.03Scale linearly by current and one-way length
Use notes
  • Use this table for preliminary reference and arithmetic checks only.
  • Confirm equipment ratings, product markings, installation conditions, utility requirements, and the local authority requirements before design or field use.