There's one thing I don't see on the labeled terminals on Derale's site that I don't care for (and just verified via the instructions):
There is no switched ignition terminal, so there is no way that I can see to shut the controller off. This would mean that the controller would leave the fans running (after engine shutdown) until the probe reaches the temperature setpoint, which is a complete waste of battery power. That could be minutes of running depending on the radiator temp and ambient temperature. There's no need to cool down a radiator that has no coolant flow, and you're not cooling the engine with no coolant flow either.
I also see it as a safety concern, because the controller is always active and is just waiting for a signal from the temperature probe to turn on the fans. That also means there is no way to stop the fans from running (if the temperature is greater than setpoint temp) without disconnecting battery power or removing the temp probe from the radiator.
The lack of ignition enable is such a bad oversight... It's a $200 controller, why not add another 7 cents of components to add an enable to work with the existing circuitry?
The easy fix is to switch battery power with a big relay, but that's something that should really be built-in to a controller of this price range using semiconductors.
Most other controllers have an input for ignition-switched power....
