Sun Xtender Technical Briefing - SOC, OCV, & DODTECHNICAL BRIEF
| Subject: | Battery Load Voltage vs. Depth of Discharge (DOD) Table
Battery State of Charge (SOC) vs. Open Circuit Voltage (OCV) Table
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Battery Load Voltage vs. DOD
Below are listed the one hour, 8 hour, 20 hour and 100 hour load voltages during the discharge cycle from full charge to 100% discharge to 1.75V/cell or 10.5V (6 cells) at 25°C (77°F).
| DOD (%) | 1 hr. Rate | 8 hr. Rate | 20 hr. Rate | 100 hr. Rate |
| 0 | 14.20 | 14.20 | 14.20 | 14.20 |
| <1 | N/A | 12.85 | 12.91 | 13.45 |
| 10 | 12.51 | 12.72 | 12.80 | 13.16 |
| 20 | 12.42 | 12.59 | 12.66 | 12.91 |
| 30 | 12.32 | 12.48 | 12.52 | 12.75 |
| 40 | 12.20 | 12.35 | 12.38 | 12.60 |
| 50 | 12.06 | 12.18 | 12.22 | 12.43 |
| 60 | 11.90 | 12.00 | 12.06 | 12.25 |
| 70 | 11.75 | 11.87 | 11.90 | 12.03 |
| 80 | 11.58 | 11.66 | 11.70 | 11.81 |
| 90 | 11.31 | 11.40 | 11.42 | 11.52 |
| 100 | 10.50 | 10.50 | 10.50 | 10.50 |
Please note that these voltages are averages and will vary slightly from battery to battery even of the same rating. They are however a good indicator of state of charge and can be used when setting low voltage alarms or disconnects for a Concorde AGM battery. Other battery types or manufacturers voltage vs. DOD may be substantially different.
Also, the data is for newer batteries with relatively few cycles. An older battery will measure a lower voltage for a given state of charge.
The 0% DOD voltage is the voltage measured upon removal of the battery from charge with no load applied. This voltage can vary depending on the set point of the charging unit.
SOC (%) vs. OCV
Another method to estimate the State of Charge (SOC) of the battery is by measuring its Open Circuit Voltage (OCV). This measurement should be made after the battery has been at rest for two to three hours with the battery disconnected from its charging source and load. The voltage is listed as Volts/Cell and for a 12V (6 cell) battery at 25°C (77°F).
| State of Charge (%) | OCV/Cell | OCV/12V Battery |
| 100 | 2.13 or greater | 12.8 or greater |
| 80 | 2.10 | 12.6 |
| 60 | 2.05 | 12.3 |
| 40 | 2.00 | 12.0 |
| 20 | 1.97 | 11.8 |
| 0 | 1.93 or less | 11.6 or less |
These voltage levels are approximate and give an indication of the state of charge of a battery at rest. As the battery ages these voltage measurements will be lower.
November 12, 1999 (EM)
The data/information contained in the Sun Xtender official website has been reviewed and approved for general release on the basis that these documents contain no export-controlled information.
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