I've got one of my new REV C relays working and want to get any comments on the operation I have decided to program into the software.

I designed a new fan fail unit because I found the fuses and fuses holders were producing a lot of heat. The condition is more pronounced when running OEM high current fans. It does not seem to cause failures since a lot of users run my original fan fail with their OEM fans.

To reduce the heating, I designed solid state fuses within the unit. That circuit is a MOSFET and the driver circuitry on each fan output that I can turn on or off when my software detects an over current condition. If I had another pin available, this new fan fail could eliminate the fan relay by connecting that fan relay signal circuit to the fan fail unit. But I’ve found most owners do not want to do wiring changes to the stock harness.

I have eliminated the fan current compare failure. I decided to show a failure (flashing the fan fail light) for either fan drawing less than 4 amps or more than 15 amps. I have set the electronic fuse to open each fan circuit if 18 amps is exceeded. The electronic fuse is reset when power (the fan relay shuts power off) to the fan fail is removed. I set the stagger fan turn on to 2 seconds. Let me know if you can think of any reason to change those values I chose. As with the first unit, once they get potted, there is no way to reprogram the software. So sorry that I can not update older REV units to this new fuseless design.


The bad:

1) If you loose the ground connection on the fan fail sockets, your fans will turn off.
2) Higher cost, more components and more time to assemble.

The good:

1) Runs cooler. Should have no heat problems even running OEM fans..
2) Electronic fuses precisely cut off excessive current much faster than any fuse for the bad fan.
3) Can stagger the fans turning on. Not able to stagger turn off because power from fan relay cuts power to fans.
4) Less problems for me potting the units without the fuse sockets.
5) Single flashing sequence shows you one fan has a problem, less than 4 amps, (electronic fuse could be tripped) or more than 15 amps
6) Double flash sequence shows both fans have the problem shown in #5.
7) Works down to 8.8 volts from fan relay. If you have my LED AC panel, I turn the green fan running LED off below 8.8 volts.