GORDON WEST REPLIES
While a digital DC voltmeter will give you resting volt readings down to 1/10 of a volt accuracy, it may not give you the sign of a weak battery during engine starting. A needle-type expanded-scale
DC voltmeter on the other hand (available from pretty much any RV or marine electronics dealer) will faithfully wiggle on engine starting, at which point all is well as long as it stays above 10 volts on cranking most engines and battery systems. Less than 10 and you likely have a weak battery, or there has either been a loss of battery fluid or you have a dirty battery terminal. Because a digital DC voltmeter usually goes in a blur during engine cranking, you don’t get a “feel” for how well your battery system is holding up, so go with analog!