Low 80s isn't too bad really. But a couple fans could probably lower you to mid to high 70s. Best temperature will probably be if you tube the hps with some fans. You can build tubes or even separators ( I had a few grows where I put a sheet of pexiglass, sealed, and some fans where the bulb was vented). But you grow area is big enough that if you circulate the air a little better you will probably get good temps.
As far as the electrical part: It's not really fire prone to wire a cell phone charger but it seems like a waste to a charger lol. That will only provide enough to power one fan. You can use the power supply to run the two fans but in this case that's going to waste a lot of electricity for two fans. I'm not sure exactly what you skill level is but you could build a simply power supply from a few parts from RadioShack.
You need a step down transformer that outputs 12 v ( or 24 V if you using 24V fans. Should be labeled on the fan ). The transformer will have a watt or amperage rating ( If its in watts divide by 12 to get the amps it puts out ). 1 amp will power around 5 - 8 cpu fans depending on the wattage ( typically around 10 - 12 watt fans ). So you can get the smallest one they have think its like 4-6 bucks maybe?
A full bridge rectifier. Ask the rep if you aren't sure what it looks like. Its a black rectangle with 4 metal pins and labeled - ~ ~ + ( Negative, A/C, A/C, Positive. )
And a capacitor. Not actually required though. It smooths out the power and suppresses spikes alittle. If you do get one I suggest getting one rated higher than 20v ( you never run a cap more than 80% of its rated voltage if you want it to last long ) and doesn't have to be very high on capacitance rating. 100 uF would work great.
The transformer is wired to a plug ( Any plugs you have laying around you don't need, old broke appliances. ) Strip the wires both the plug and the transformers ( the Transformer will have at least 4 wires. Two for the 120v, and two for 12v. Some will have 3 wires on the secondary which is called a center tap. That middle wire is so you can have 6 volts or half of what the transformer outputs. ) You wire the plug to the primary side of the transformer ( Read the box, ask the store rep, or look at the wire. Generally they code the 120 side black and white. ) It doesn't matter which wire is hot or neutral the transformer doesn't care.
The wires on the other side go to each of the AC pins on the rectifier ( usually the middle 2 ). The -, and + on the rectifier is your DC power. Wire the Cap ( if using one ) Negative to Negative, Positive to Positive. Wire each fan in parallel or in the same fashion as the cap. Each fan wires + to + and - to - ( should be listed on the fan, if not they usually code Red + and Black - ). This way each fan gets 12 volts and will use as much amps as it requires. Make sure all connections make good contact and are insulated. The only electrical danger is the two wires from the plug that is 120 volts, if not well insulated could give you nice zap. You can add a fuse on both sides of the transformer if you nervous.
It's not too bad making it though. Cost maybe 10 - 15 $ and will power the fans you want. I'd be more then willing to help you if you do it this way. Or any other way lol. I have used this a few times to run many of my fans ( Later I had to build a SMPS to run them but that is probably a little complicated for you :S ). Goodluck!
StonedScientist
