I have an Infinity variable voltage PV and it works fine. However, I've found my sweet spot is right at 4.5 volts. I'd like to get another unit but don't really need or want to pay for variable. 3.7 volt is not enough and 5 volt is too much. Does someone make a 4.5 volt unit? The smaller the better. Using and have a lot of 510 atties so I don't really want to go the HV / LR atty route. Any suggestions would be appreciated. Thanks.