Hey guys. I am trying to put a fan into a helmet. I have a 3.7VDC, 650mAh lithium ion rechargable battery. I have sourced and found a great battery! The afore mentioned battery is the constant. Now I am having problems finding a DC Fan that will work with my battery. So far I have found only 5V DC Fans. I feel as though I am not getting enough power to run the fan! When I hook the 3.7V battery up to the fan, it only last about 4 hours on one charge. When I hook 3 1.5V AAA batteries up to the same fan, it runs much stronger and longer! What do you suggest I do in order to complete my project? I do not think a 3V DC fan exists. Thanks in ADVANCE!!