Hey guys, I have three Nico solar vents. Two have battery backups for night time. These work when the sun is out but the batterys are dead. I replaced the batterys with normal batterys and they still will not work out of the sun. Do the batterys have to be the same as what came out, rechargeble C , or should a normal C battery work. I cant find the voltage indicator on the rechargeble batterys but would ASSuMe them to be 1.5 volts. thanks for any help. Howard