Q. We would like to check and maintain our batteries. What are the voltage
and specific gravity readings for a 12-volt lead-acid storage battery that indicate charge
A. A 100 percent charge will be 12.66 volts or 1.280-1.260
specific gravity (tested with a hydrometer). A 75 percent charge level will produce about
12.45 volts or 1.250-1.230 specific gravity. A 50 percent charge will give you about 12.30
volts or 1.220-1.200 specific gravity. Volt readings of 12.15 or 1.190-1.170 specific
gravity indicates a 25 percent charge.