ACDelco PowerSports - Checking Open Circuit Voltage; OCV Measurement Guidelines; Battery Stabilization for OCV; State-of-Charge Estimation Table

INSTRUCTION SHEET
Checking Open Circuit Voltage:
OCV may be used to estimate the Lawn and Garden battery state-of-
charge. Observe the following guidelines:
 Use a voltmeter that has been verified as accurate. An
inaccurate meter will give inaccurate results. The meter should
read to the nearest 0.01 volts.
 When checking OCV, the vehicle engine and all current drains
must be OFF. Any current flow into or out of the battery will
cause an incorrect voltage reading.
 The battery must be stabilized before reading the OCV. If the
battery has been charged or used in a vehicle in the past 12
hours, remove the surface charge (apply a 300amp load for 15
seconds). If the battery has just been discharged, allow at
least 15 seconds for the voltage to stabilize, then read the
OCV.
 Use the following table to estimate the state-of-charge based
on the battery temperature:
Stabilized
OCV (Volts)
% Charge*
at 0°C (32°F)
% Charge* at
25°C (75°F)
12.75
100%
100%
12.70
100%
90%
12.60
90%
75%
12.45
75%
65%
12.20
65%
45%
*Estimates Only. Batteries vary +10% by model.
 Keep batteries at 65% of full charge or higher. If the OCV falls
below 12.4V, recharge the battery.
 IMPORTANT: When a battery needs charging, always charge
it fully. If you don’t:
 Retests with electronic testers may be inaccurate.
 Full shelf life will not be available if returned to
storage.