How to determine batteries are "good" or "defective" when they are used during the initial period or the warranty. Several tests are listed as follow:

1. Some test parameters may show the battery’s condition: open circuit voltage, internal resistance, battery capacity and the charging behavior. Using one parameter for being criterion is better double-checked by other parameters. The most commonly method is the measurement of open circuit voltage.

2.The open circuit voltage of new batteries should be above 6.45V(for 6V battery) or 12.9V(for 12V battery). After transportation, storage and different discharge factors, batteries’ open circuit voltage will have values from 12.9V to even 0.0V. If the battery’s open circuit voltage is below 1.93Vpc, or 5.79V(for 6V battery), or 11.58V(for 12V battery), this battery is a defective battery due to over discharging or some kind of deterioration. This kind of battery has permanent damage even after recharge. To evaluate batteries with voltages higher than the above-mentioned value, fully recharge the battery is necessary before any measurements.

3.If some batteries' open circuit voltage are far from its average values, they can be classified as defective battery.

4.The open circuit voltage should be measured by standby one hour after recharge. The fully charged battery with open circuit voltage smaller than 6.2V(for 6V battery) or 12.5V(for 12V battery) is a defective battery.

5. The open circuit voltage of The fully charged battery should be higher than.

6.45V(for 6V battery) or 12.9V(for 12V battery). If the battery has values between 6.2 ~6.45V(for 6V battery) or 12.5 ~ 12.9V(for 12V battery), it may not be fully charged, and may need recharge with proper charger. If this condition is not improved, the battery’s capacity may have been reduced.