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Hooking Up 12v Pusher/Puller Fan?

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GSIntegral

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Beginner.. I'm looking to possibly get one or two small 10" cooling/radiator (pusher/puller) fans and mounting them in the back of my car for more airflow. Summer time sucks and my a/c is out at the moment. I wouldn't have a problem hooking these straight up (full load) with a fuse and switch but I am looking at making them variable instead. My first thought is to splice into the cars preexisting blower motor and use that switch and resistor but I didn't know if the resistor would be able to hold the load safely?

My second question is if I build a separate system, would I even need a resistor in the system if it's going to be adjustable or can I just get say like a rotary switch?
 

spec

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Hy GSIntegral,

Welcome to ETO. I see you are from the US; care to tell us which state.

Your requirements should be realized quite simply but we need to know the maximum current that your fans take on full blast. If you are going to measure this rather than looking at the fan information, do so when the automobile engine is running when the battery voltage will be at its highest.

To answer your second question, yes a rotary switch would be possible but you would need to specify how many ways you want.

What you would do in simply switch in different resistors in series with the fan to get. different speeds. The resistors will get hot so they would need to be mounted on a heatsink and not in the cabin.

spec
 
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GSIntegral

New Member
Thanks for the info. I'm from Oregon, my background is basically computers and horticulture: turf and landscape maintnance.

I don't have the fans yet i was thinking about getting them here in the next day or two. Then I'll see what the load rating is on full.

As for the PWM's, and resistors..i was thinking the heat might be a factor for resistors that's why if it's safe I'd try to tap into my preexisting system. Don't really want an open heat source somewhere. I'll look into PWM's. For some reason I thought they were preset variables.

I've seen the "kits" you can get but all those seem to run off thermostats.
 

GSIntegral

New Member
Kind of at work at the moment. From what I recall the motors are like 5.4 amps each on paperwork. I did see those pwm's when I was searching. I wasnt sure if the wire gauge would accommodate. I'm realizing the wires aren't as big as I'm thinking. The last car I worked on had like 10 gauge wire for the radiator fans but mine aren't nearly as large.
 

spec

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Kind of at work at the moment. From what I recall the motors are like 5.4 amps each on paperwork. I did see those pwm's when I was searching. I wasnt sure if the wire gauge would accommodate. I'm realizing the wires aren't as big as I'm thinking. The last car I worked on had like 10 gauge wire for the radiator fans but mine aren't nearly as large.
Am I then correct that you will have two fans each taking 5.4 Amps making a total of 10.8 amps for the two fans. If that is indeed the case, pulse width modulation would be best as chemelec suggested.

spec
 

GSIntegral

New Member
Ampacity for 10G is 30amp.
12g =20amps
14g = 15amps.
Max.
Cool, I forgot I downloaded a couple charts that showed that as well as wattage ratings for the gauges. I installed a 4G from the battery to a fused distribution block in the back. I still need to do some calculations for a third amplifier addition/install (another reason for the fans). But on the previous statement I do remember something of the other vehicle being higher rated.
 

GSIntegral

New Member
I do thank you guys for the input. I knew there was another way around the resistor. I found this..? http://www.ebay.com/itm/370962506627 might be a little over kill but I like the box and I might have a spot I can nudge it into for ease of use and discreetness.

Edited: I was hoping to get the fans in the next day or two and throw something together to post pics and stats. My local auto parts store has these Hayden 10" in stock. http://www.haydenauto.com/Featured Products-Electric Fans/Content.aspx But of course while browsing on EBay I found this other brand FF Dynamics.. "On paper" it's showing it will be more airflow with a smaller 8" and possibly to be a better setup. http://ffdynamics.com/products/ffd8
 
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chemelec

Well-Known Member
The PWM I Posted in #3 will easily Handle 30 Amps, if you put a Heat-Sink on the Mosfet.
At 10 Amps at would run VERY COOL.
It is also possible to use a Rotary Switch with suitable resistors to create predetermined speeds.
 

spec

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Most Helpful Member
I do thank you guys for the input. I knew there was another way around the resistor. I found this..? http://www.ebay.com/itm/370962506627 might be a little over kill but I like the box and I might have a spot I can nudge it into for ease of use and discreetness.

Edited: I was hoping to get the fans in the next day or two and throw something together to post pics and stats. My local auto parts store has these Hayden 10" in stock. http://www.haydenauto.com/Featured Products-Electric Fans/Content.aspx But of course while browsing on EBay I found this other brand FF Dynamics.. "On paper" it's showing it will be more airflow with a smaller 8" and possibly to be a better setup. http://ffdynamics.com/products/ffd8
With fans the bigger the better. Be very cautious about specifications on eBay.

spec
 

GSIntegral

New Member
With fans the bigger the better. Be very cautious about specifications on eBay.

spec
Agreed.. I'm still leaning towards 10". I have the room but thinking about the design and flow. And agreed as well. I only do EBay for certain things and try to research companies/products before hand. Also agreed with the specifications. Summitracing.com is showing, I think a 10" that does some 2,000 cfm's, but people are saying it barely puts out like 600.
 
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