While working on a wind/PV system in a remote area of the Philippines the need for a voltmeter
which showed the system (battery) voltage in detail arose. Only analogue V and A meters were available in the
local town. This simple design explains in detail how to convert a low range ammeter into a voltmeter that will display
an expanded range of voltages. For a lead-acid battery this was chosen to be 10 to 16V DC.

download the pdf voltemeter plans here