Taurus Fan Draws Battery Down

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Jul 22, 2008
My Taurus Fan, when on high draws my battery down to the point where it won't start. The power to the fan comes from the battery and through a fused link and then to a forty amp relay. I have a CS-130 alternator that cranks out the amps and supplies almost 14 volts to the battery when the fan is not on. I am only running the high speed. The low speed just doesn't cool well enough. The fan turns on and off with a temperature switch.

Any ideas on why it is pulling my battery down so much?

If I guessed it would be mainly at idle or low RPM and your alternator doesn't have the oomph to keep up at the low RPM, even worse if you have the lights on etc. The fan can draw quite a bit of currrent on start-up (over 70 amps) and runs 30-ish continuous once spooled up. You can make sure the fan turns smoothly and check how much current it pulls with a clamp on amp probe to see if it drawing an unusual amount of current but the fan is kinda a monster and sucks juice like one. These numbers are for a MKVIII fan but the Taurus should be similar.

You may find yourself sourcing a high output low RPM alternator if it continues to cause trouble.
Thanks for the ideas. The battery is new and I switch the fan off when the rig turns off. At this point I may just look into going back to an engine fan with a shroud. The problem there is the engine was mounted low and does not center on the radiator.
Many OEM engine driven fans are not centered on the radiator. The shroud simply should ensure that the entire radiator face is isolated from the rest of the engine compartment via a "box" . A ventury in the form of a ring extending from the shroud (box) to the mid point of the blade or as far as the engine side of blade is essential to optimize fan efficiency. Consult the source and/or the vehicles it was designed for use on to confirm the intended fan insertion with in the ventury.

X2 dynosaur, My controller failed and went to the Painless fan control unit. had some starting issues when warm. Never failed to start just seemed to be struggling. Never had these issues with the controller. Will be going back to one soon.
Installing a smaller pulley on the CS130 will increase it's output at idle. An alternator shop can switch it over in a few minutes.

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