Electric Vehicle Discussion List - Voltage vs SOC for USBMC golf car batteries

Voltage vs SOC for USBMC Golf Car Batteries
by Nawaz Qureshi, Vice President of Engineering, US Battery Mfg Co

Open circuit voltage is not the same thing as the float voltage listed on our web site. Float voltage is a charging voltage at which the battery is connected to a charger during a very long period of inactivity (months), and will still stay charged and ready to serve.

Voltage is not an accurate indicator of state of charge (SOC). However, the table below describes SOC estimates for a 6 volt battery after several hours of standing off charge and unused.

Open Circuit Voltage Electrolyte Specific Gravity @ 80°F State of Charge

≥6.3 ≥1.265 100%

6.2 - 6.3 1.225 75% - 100%

6.1 - 6.2 1.190 50% - 75%

6.0 - 6.1 1.155 25% - 50%

5.85 - 6.0 1.120 0% - 25%

<5.85 <1120 0%

Open Circuit Voltage	Electrolyte Specific Gravity @ 80°F	State of Charge
≥6.3	≥1.265	100%
6.2 - 6.3	1.225	75% - 100%
6.1 - 6.2	1.190	50% - 75%
6.0 - 6.1	1.155	25% - 50%
5.85 - 6.0	1.120	0% - 25%
<5.85	<1120	0%