Hey, Mike.
In a way, you nailed it ... but not exactly.
Here's the full scoop on it from MadElectrical.com:
The reason for our recommendation is to prevent slow-meltdown of the
wire harness connector at the base of the relay. Electric motors are
prone to overheating connections and switches in power delivery
circuits.
Two Relays can handle most fan systems. However, with only one relay
pulling the entire load for powerful radiator fans, the terminals
will often overheat if the fan system is used for long periods of
operation.
Meltdowns often occur with the Male/Female-Flat Blade terminals in
continuous duty/high current demand automotive systems - especially
with power loads to electric motors.
The current load limitation that these relays can handle is with the
wire connection design that will join the wires to the relay, rather
than the contacts inside of the relay being the weakest part --
which is why it will do no good to compare the current rating
published on the relay to the RMS current draw rating of a radiator
fan motor.
Alan
http://www.AlanHorvath.com
Acoustic Rock ... for real.
Mike & Inez Plucker wrote:
> OK Alan I will bite. Why the two relays? Is this incase one quits?
> Mike 50 3100
>
>> If you do go this route, I suggest *no* circuit breaker ... *no*
>> fuse on the fan ... but, rather, use a fusible link. See this:
>> http://alanhorvath.com/54chevy/fusible_links.php
>> Also, I put *double* relays, too - see this:
>> http://alanhorvath.com/54chevy/mad_electrical_2.php
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