Electric Fan Voltage Drop

The alternator is tricked into working harder to compensate for the 1 2v difference it is seeing.

Electric fan voltage drop.

When electric fan installs don t perform as expected the problems are often traceable to under wiring and or poor splices and grounds. You may double the fan belt or use a serpentine belt so it won t slip. The actual voltage drop can vary depend on the condition of the wire the conduit being used the temperature the connector the frequency etc. Put a diode in series at the alternator on the excite trigger wire.

What the diode does is drops the voltage by about. Grab a volt meter and measure the voltage at the alternator. It is recommended that the voltage drop should be less than 5 under the fully loaded condition. When the air is on and the auxiliary electric fan kicks in my voltage drops from 14 2 down to about 12 5 13.

If does not drop then run a heavyer gauge wire between the alternator and junction terminal. If dip to 11 volts then your alternator is either not delivering the 100 amps or the fan belt is slipping. I have never had any problem with the battery going dead or any long term charging issues. Might help you a lot with the voltages your are seeing.

I switched to a 170 amp holley alternator along with a new drive setup on my ls and added a 4 awg feed wire. There must be little or no voltage drop at the fan motors.