car radiator fan

[mart_1986]

hi there

im after a power supply to run a car radiator fan which is around 12v at 10-15amps must come off mains 240v

 

[smanches]

Computer supply would probably be the most cost effective.

 

[mart_1986]

thanks you

 

[tcmtech]

A cheap general purpose 15 - 20 amp battery charger will do the job just as well!
The computer power supply may not like having a big load on the 12 volt output while not having any loads on the rest of the outputs. It could become unstable and burn out rather quickly.

 

[Sceadwian]

You need a pretty decent power supply to get 15 amps off the 12V line of a PC supply. I'm guesing in the neighboorhood of 400+watts supply. Ohm's law doesn't apply in this case because most of the power that comes off a PC supply is on the 3.3 and 5 volt lines so the 12 volt bus has a much more limited current output. You can't beat the cost though.
A mpja.com catalog I have here has a 650w supply that can do 22A on the +12 line is only 35 dollars. If you're worried about stability you can place a few fans or high power resistors on the +5 line, you only need to draw a few hundred ma for the supply to maintain regulation.

 

[mart_1986]

its going to on on a therostat so when the temperture get higher than 20c or 68f

how many would i be able to run at the same time off 1 psu and also 1 battery charger?

would 5v make these fans run as i dont need them to run at full power

 

[tcmtech]

So what are you doing with these fans?

 

[mart_1986]

So what are you doing with these fans?

i keep racing pigeons so i need to keep them at a temperture at 20c in the summer

 

[Vizier87]

i keep racing pigeons so i need to keep them at a temperture at 20c in the summer

Aww.. that's sweet.
Use the brushless dc motors (The ones used to cool your desktop computer) then. Nowadays they also have fancy LEDs which glower prettily so that should keep the pigeons happy They operate at 5V and the speed is always constant, and the motor can run for as long as you want.

 

[Boncuk]

I guess a car fan is much overpowered for your application. It produces windspeeds making your pigeons "hover" at 80km/h.

All you need is a fan of a volume high enough to replace the air at a rate of 6 to 8 times per hour.

I suggest to use multiple fans of low airspeed and -pressure speed and high volume flow.

There are mains operated fans on the market with a diameter of 92mm. They deliver 88.3 cubicmeters/h at a noise level of 31dB. (price ~ US$15)

Reducing rpm and air flow for the car fan will definetely be higher in price.

Using two of them should suffice unless your pigeon house has the dimensions of a concert hall.

Boncuk

 

[mart_1986]

I guess a car fan is much overpowered for your application. It produces windspeeds making your pigeons "hover" at 80km/h.

All you need is a fan of a volume high enough to replace the air at a rate of 6 to 8 times per hour.

I suggest to use multiple fans of low airspeed and -pressure speed and high volume flow.

There are mains operated fans on the market with a diameter of 92mm. They deliver 88.3 cubicmeters/h at a noise level of 31dB. (price ~ US$15)

Reducing rpm and air flow for the car fan will definetely be higher in price.

Using two of them should suffice unless your pigeon house has the dimensions of a concert hall.

Boncuk

so what sort fans would you suggest i didnt know the noise level was that level got to be almost silent

 

[tcmtech]

If you want silent then you dont want a vehicle radiator fan!
Many of the small fans they sell for in home use are very quiet and cheap too.
I picked up a set of 20 inch box fans for $17 each a few years ago that are very quiet.
There are smaller ones too.

 

[Boncuk]

31dB is almost as loud as whispering. You can use those fans without any rpm regulation.

If the pigeons get nervous from the sound level you could add silencers not reducing the exhaust port cross section of the fan for maximum air flow. Silencers are easy to make and they are very effective.

In large buildings with huge fans for air movement inside the building there are silencers. Passing the air intake you'll hear a low volume wind. Inside the fan chamber you need ear protection because of the fan's noise of 78 to 85dB.

You might also consider bathroom or kitchen fans. They have a greater diameter and one of those will deliver between 1,000 and 3,000 cubicmeters of air volume per hour.

Boncuk

 

[HarveyH42]

Pigeons are highly adaptive, they'll get use to the noise, if its not painfully loud. The automotive fan won't be running at max speed, since the car voltage is usually a little higher. Doubt they draw 10 amps either, but never tested one. Be sure to mount the fans outside the cage, birds just aren't that smart...