Electric Fan Voltage Drop

The voltage drop test is a dynamic test intended for use mainly with high current draw systems such as the starting system charging system or items such as a heater fan electric fuel pump or.

Electric fan voltage drop.

Voltage would start off at 14 0 and drop down to 12 5 with both fans on entropy fans are big power hogs and everything else on. I switched to a 170 amp holley alternator along with a new drive setup on my ls and added a 4 awg feed wire. The actual voltage drop can vary depend on the condition of the wire the conduit being used the temperature the connector the frequency etc. Might help you a lot with the voltages your are seeing.

Grab a volt meter and measure the voltage at the alternator. Basic voltage drop law v drop ir. If dip to 11 volts then your alternator is either not delivering the 100 amps or the fan belt is slipping. When electric fan installs don t perform as expected the problems are often traceable to under wiring and or poor splices and grounds.

There must be little or no voltage drop at the fan motors. The alternator is tricked into working harder to compensate for the 1 2v difference it is seeing. You may double the fan belt or use a serpentine belt so it won t slip. When the air is on and the auxiliary electric fan kicks in my voltage drops from 14 2 down to about 12 5 13.

What the diode does is drops the voltage by about. Put a diode in series at the alternator on the excite trigger wire.