I recently purchased a tower expanded scale voltmeter (to replace one I had for many years). The new voltmeter does not appear to be reading correctly, as it seems to always be reading low. I have tested it on several batteries, included two that are new, and none of them read in the green part of the meter. It is not worthwhile to try for a warranty, since it would cost more to ship the meter back and forth than the voltmeter costs. Is there any easy way to verify the amount of error in the voltmeter and is there a way that it can be calibrated? Thanks for any advice.