Car battery (Automotive battery) supplies the electrical energy. Car battery powers the starter motor, lights and ignition system of a vehicle’s engine. Different ratings of lead-acid type battery are used in cars. Full chart of various battery voltages with charge state is given below:

Specific gravity at 80 degree Farenheit (unit less)Battery voltage (6V)Battery voltage (8V)Battery voltage (12V)Battery voltage (24V) Battery voltage (36V)Battery voltage (42V)Battery voltage (48V)Battery voltage (72V) Battery voltage (120V)Charge in Percent (SOC)
1.2766.37 volts8.49 volts12.73 volts25.46 volts38.22 volts44.59 volts50.92 volts76.44 volts127.4 volts100
1.2666.34 volts8.45 volts12.68 volts25.35 volts38.04 volts44.38 volts50.70 volts76.08 volts126.8 volts95
1.2576.31 volts8.41 volts12.62 volts25.24 volts37.86 volts44.17 volts50.48 volts75.72 volts126.2 volts90
1.2466.28 volts8.37 volts12.56 volts25.12 volts37.68 volts73.96 volts50.24 volts75.36 volts125.6 volts85
1.2376.25 volts8.33 volts12.50 volts25.00 volts37.50 volts43.75 volts50.00 volts75.00 volts125.0 volts80
1.2256.22 volts8.29 volts12.43 volts24.87 volts37.32 volts43.64 volts49.74 volts74.64 volts124.4 volts75
1.2166.19 volts8.25 volts12.37 volts24.74 volts37.14 volts43.33 volts49.48 volts74.28 volts123.8 volts70
1.2136.16 volts8.21 volts12.30 volts24.61 volts36.93 volts43.08 volts49.22 volts73.86 volts123.1 volts65
1.1946.12 volts8.16 volts12.24 volts24.48 volts36.72 volts42.84 volts48.96 volts73.44 volts122.4 volts60
1.186.09 volts8.11 volts12.17 volts24.34 volts36.51 volts42.59 volts48.68 volts73.02 volts121.7 volts55
1.1716.05 volts8.07 volts12.10 volts24.20 volts36.30 volts42.35 volts48.40 volts72.60 volts121.0 volts50
1.1566.01 volts8.02 volts12.03 volts24.06 volts36.09 volts42.10 volts48.12 volts72.18 volts120.3 volts45
1.1475.98 volts7.97 volts11.96 volts23.92 volts35.88 volts41.86 volts47.84 volts71.76 volts119.6 volts40
1.1325.95 volts7.93 volts11.88 volts23.77 volts35.67 volts41.61 volts47.54 volts71.34 volts118.9 volts35
1.1235.91 volts7.88 volts11.81 volts23.62 volts35.46 volts41.37 volts47.24 volts70.92 volts118.2 volts30
1.1075.87 volts7.84 volts11.73 volts23.47 volts35.22 volts41.09 volts46.94 volts70.44 volts117.4 volts25
1.0975.83 volts7.77 volts11.66 volts23.32 volts34.98 volts40.81 volts46.64 volts69.96 volts116.6 volts20
1.0815.79 volts7.72 volts11.58 volts23.17 volts34.74 volts40.53 volts46.34 volts69.48 volts115.8 volts15
1.0725.75 volts7.67 volts11.51 volts23.02 volts34.50 volts40.25 volts46.04 volts69.00 volts115.0 volts10

*This is Open circuit voltage reading

*Specific Gravity is described in 800F temperature and per cell


Specific gravity

Specific gravity is the ratio of the density of any substance to the density of any reference substance. It is measured as the ratio of the mass of any substance to the mass of reference substance for the given same volume.

Specific gravity can be expressed mathematically as

S.G. = weight of equal volume substance / weight of water in air

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