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.

It may be your leads and not the ESV. Because the ESV is loaded and draws current, any resistance in your leads or connections will cause a voltage drop. Try a different set of leads, preferably leads with short, large diameter wires and gold plated pins on the battery connector.

I have found Tower is excellent about defective parts. If you call and explain the situation they may just send you a new one without asking you to return the one you have.

And yes, the ESV can be calibrated. On mine there are calibration pots inside. You would need an accurate voltage source or volt meter. Maybe there is an electrical guru in your club who could help.