A golf cart battery voltage chart is useful only when you know the battery chemistry and testing conditions. The values below are open-circuit reference voltages for Trojan flooded lead-acid batteries after resting. They should not be used as a lithium state-of-charge chart, and AGM values can differ.
Flooded lead-acid open-circuit voltage chart
| State of charge | 6V battery | 8V battery | 12V battery | 36V pack | 48V pack |
|---|---|---|---|---|---|
| 100% | 6.37V | 8.49V | 12.73V | 38.20V | 50.93V |
| 80% | 6.25V | 8.33V | 12.50V | 37.49V | 49.99V |
| 60% | 6.12V | 8.16V | 12.27V | 36.72V | 48.96V |
| 50% | 6.02V | 8.07V | 12.10V | 36.31V | 48.41V |
| 40% | 5.98V | 7.97V | 11.89V | 35.87V | 47.83V |
| 20% | 5.83V | 7.77V | 11.66V | 34.97V | 46.63V |
Rest the batteries before using the chart
Trojan recommends that batteries remain idle with no charging or discharging for at least six hours, preferably 24 hours, for an accurate open-circuit voltage test. A reading taken immediately after charging can be elevated by surface charge; a reading taken right after driving can be depressed by load.
Why a 48V pack reads more than 48V when full
“48V” is the nominal system voltage. Six fully charged 8V flooded batteries at about 8.49V each add to roughly 50.93V at rest. Four fully charged 12V flooded batteries at about 12.73V each are also around 50.9V. That is normal.
Check individual batteries, not only the pack total
A total pack reading can hide imbalance. One weak battery may be partly masked by stronger batteries. Measure each battery and compare them under the same resting conditions. A battery that consistently sits lower than the others deserves further testing.
Use our multimeter testing guide for the step-by-step process.
Flooded batteries are better confirmed with specific gravity
Trojan states that specific gravity is the most accurate state-of-charge measurement for flooded lead-acid batteries. A hydrometer can show cell-to-cell differences that pack voltage cannot. Trojan lists 1.277 or greater at 80°F (27°C) as full charge for most of its flooded batteries.
Temperature changes the interpretation
Battery voltage and specific gravity are temperature-sensitive. Charging voltages also require temperature compensation. Use the battery manufacturer’s temperature-correction procedure when the pack is much hotter or colder than the reference temperature.
AGM batteries use different reference values
Do not automatically apply the flooded table to AGM batteries. Trojan’s AES AGM guidance, for example, lists approximately 12.84V at 100%, 12.54V at 75%, 12.24V at 50% and 11.94V at 25% for a 12V AGM battery at rest. Use the chart published for your exact battery type.
Lithium batteries need a different approach
LiFePO4 packs maintain a relatively flat voltage through much of their usable range, so voltage does not map to state of charge in the same way as flooded lead-acid. Use the BMS, display or manufacturer-specific state-of-charge data. Never use the flooded chart to decide whether a lithium pack is “50% charged.”
What a low reading can mean
- The pack is simply discharged.
- One or more batteries are weak or imbalanced.
- A battery has a bad cell.
- There is an excessive parasitic load during what should be a rest period.
- The charger is not completing the correct profile.
- Cable resistance or poor connections are affecting testing under load.
Resting voltage is not a load test
A battery can show a reasonable open-circuit value and still sag badly when the cart accelerates. If range or power is poor despite normal resting voltage, compare voltage under a controlled load or have the pack professionally tested.
When should you recharge?
For flooded lead-acid battery life, avoid routinely driving the pack deeply discharged. Recharge after use according to the battery and charger manufacturer’s guidance rather than waiting for voltage to reach the bottom of the chart.
Bottom line
Use the voltage chart as a rested, chemistry-specific reference. Compare individual batteries, confirm flooded state of charge with specific gravity when needed, and use the BMS for lithium. A single voltage number does not replace a complete battery diagnosis.
Reference: Trojan Battery open-circuit voltage table.
Charging voltage is not the same as resting voltage
Do not compare a battery that is actively charging with the open-circuit table. A charger intentionally raises voltage above the resting value during bulk and absorption stages. Likewise, a float or maintenance voltage can sit above normal open-circuit voltage. Let the pack rest before using the table to estimate state of charge.
Use pack voltage to find the problem, not to end the diagnosis
If a 48V pack rests low, measure each battery next. One 8V or 12V unit may be disproportionately weak. If every battery is equally low, the issue may simply be incomplete charging. If resting readings look normal but the cart loses power quickly, test under load and inspect connections. See our weak-battery troubleshooting guide for the next steps.
