Electric fan wiring setup

[jdmfreak]

As far as relays go do you guys see a problem with using one off my parts 88? Such as the main relay in the fuze box under the hood?

 

[jetjock]

No. Again, how much current does the fan need? Use 30 amp relays minimum. For two fans, bigger. Bosch or equal.

For automotive work soldering, if done right, is adequate. I have no illuisons broke kids working on old cars are gonna go out and buy the proper crimp stuff even though with a lttle effort it can be had reasonably cheaply. Just that, imho, electric fans need to be a cut above in reliabilty. I still don't like them for cooling though, which is why I put an alarm on the car that has them.

 

[jdmfreak]

Overall size is 15.5x26.25x2.63 inches, covers the 7M radiator *completely*. Fan operates at 2000 rpms, 19.5A, 2500CFM.
I bought them through suprasport

 

[jetjock]

Well, the inrush will be more but the typical 30 amp Bosch should do. You could always use 50s. I think the newest Dakota controller does 70. Course, relays are only one part of the equation. There can't be any weak links anywhere in the install. One thing I dislike about Bosch relays are the QC type connections. Yet another reason to use high quality terminals. Just overbuild it and you'll be fine.

 

[IJ.]

When I ran the MoTeC PDM's to control everything in my Mk3 I was AMAZED at how high the inrush was....

Ended up Softstarting everything that had high loads.

 

[jetjock]

Yep, until the rpm (and thus the counter-emf) comes up they're really sucking it down. Speaking of counter-emf, some people use the 5 terminal version of the Bosch to short the fan when it's not needed to limit freewheeling.

I like those PWM fan controllers. There's something elegant about varying fan speed to what's required.

 

[jdmfreak]

The new flexalite fan controllers are variable speed

 

[jetjock]

Yeah, I just took a look at those. Couple of them are good for 45 amps. That'll work. One nice thing about the Dakota is the digital readout.

 

[jdmfreak]

So for starters would 2 40 amp relays be sufficient? One for the thermostat and one for the override switch?

 

[jetjock]

Yep, should be OK (only need 2 relays if you want the fans off with the key) as long as that stat is good for the current. Just don't skimp on the rest of the wiring and fuse it as close to the battery as possible. I'd still use an alarm. Shouldn't cost more than 10 bux for a Sonalert. Get one that's pulsing.

 

[jdmfreak]

Alright I will get a 40 amp relay 30 amp fuze as short as wire(10gauge) as possible and use the controller I have till I can get a dakota... It looks totally worth the money and I like the digital readout... Will get that alarm and also wire in a override switch then...

All of this will happen with my next paycheck.... I don't wanna skimp on this thank you guys

 

[jetjock]

That Dakota is a new model. The older one (still had the readout) was cheaper if you can find it. "Sonalert" is a Mallory trade name btw. I shouldn't have used it because real Sonalerts aren't cheap. There's plenty of copycat ones out there that are though. And again, if that mechanical thermostat you bought can't handle 30 amps it shouldn't be used...

 

[jdmfreak]

Ok I ran to get a relay I wall check the amperage when I get home

 

[jdmfreak]

Update: it is a 16 amp thermostat... But I still should be able to use it if I wire it to activate the 40amp relay correct?

 

[jetjock]

Yep, just have to wire the control to switched +12. And doing it this way means you no longer need a second relay.

 

[jdmfreak]

Awesome

 

[jdmfreak]

Good for now

16amp Thermostat from switched black and yellow wire at alternator to relay

40amp Relay straight from battery to fans