Figured I should do some thermal testing outdoors, as it was nearly 90F this afternoon.
We punched two full sized fan holes on the prototype overnight charger. To start where the first test left off, we sealed the new fan holes so I could try the first variation.
Fan exhausting instead of blowing air into the box.
Into the box test got up to 102F, out of the box only got up to 96F, which makes sense as the replacement cooler air is being drawn in through all the louvers, so it is distributed more evenly than when the box is pressurized, and we try to blow the air out.
Variation # 2
I connected a second fan, which was also drawing air out of the box, and the box then stabilized at 93F.
Brought the test into an 85-90F outdoor environment.
Temp got up to about 106F with both fans.
Again sealed the second fan, and saw the box temp get up to 115F, and still rising, so I removed the tape, and after an hour we were back at a stable 107F
Variation # 5
Did not get a chance to try a final variation where one fan blew in, and one out, but expect that it will not work as well as the both drawing air out, as it would virtually eliminate any fresh air frpm being drawn in through the louvers.
Bottom line, I thing we should have two fans, and will run the 50 overnight charger boxes through the punch.