This chart shows the relative state of charge for 12 volt and 6 volt batteries. For 8 volt batteries multiply the 12 volt readings by .667. For 24 volt systems, multiply the 12 volt readings by 2.
These readings should be taken by a digital voltmeter prior to charging the battery. Corresponding hydrometer readings from the 12 volt scale portray the same relative state of charge regardless of battery voltage.
12 volt battery 6 volt battery State of Charge
12.66 6.33 100%
12.58 6.29 90%
12.51 6.25 80%
12.45 6.22 73%
12.43 6.19 70%
12.35 6.17 60%
12.28 6.14 50%
12.19 6.09 40%
12.12 6.06 30%
12.04 6.02 20%
11.97 5.98 10%
11.81 5.91 -0-
