Discussion in 'Workshop Forum' started by Pete Whitstone, Jul 27, 2019.
Anybody ever actually measured it? I'm referring to the radiator fans here.
I have not measured it, but would be interested in the results as well. I know fans have a pretty big amp spike when first kicking on, then it levels down rather quickly. I imagine the stock original fans have a rather large draw compared to aftermarket stuff. I think the condition of the wire harness, relays, etc will be a factor if testing them on the car. Maybe an inductive meter with the fan wired directly to a battery might be a better measure to go by.
I went down a similar route to you a while back wanting to wire up two fans so i tested them both:
I rigged up a test on the bench and found as follows (both fans show same readings)
On a very “Hard start” ie the current draw shown by jabbing terminals with the connectors produced instantaneous flick of analogue meter to over 75A, digital only registers 15A each fan (which I think is the most relevant given the standard relay in the fuse box is 25A
Run current draw 12.5A each
Hope this helps
Thanks RDS! Good info.
Those numbers sound about right. I read a similar test on larger fans for American cars with up to 30-40 amp initial kick in and 14 amp normal running. The initial spike is very brief so it could be quite high but still not trip a lower amp fuse. But I think it really varies with different fans; weight of the blades, motor specs, overall size, etc. Most aftermarket fans will be much less that most factory fans. Obviously keep in mind that if two fans are wired to operate together then the circuit is handling double that load (if on one circuit).
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