Why Golf Cart Batteries Lose Charge When Not in Use

You roll your golf buggy back into the garage after an enjoyable weekend drive. A few weeks pass. It might be the colder season, or perhaps daily life simply takes priority. When you eventually try to power it up again, nothing happens.

That’s when most owners begin to question themselves. Did I forget to put it on charge? Has the battery been harmed by sitting idle? Is this expected wear, or something that will cost a lot to fix?

When the voltage has quietly fallen even though the cart hasn’t been used, it can feel frustrating. In reality, however, batteries do not “pause” just because we do. Chemical reactions continue internally, electronic components may draw small currents, and ambient temperature continues to influence performance.

Knowing why golf cart batteries lose charge while not in use is not simply about curiosity. It helps extend service life and reduces the risk of replacing batteries sooner than necessary.

Is It Normal for Golf Cart Batteries to Lose Charge?

Yes. Every type of battery will gradually lose some charge, even when disconnected from any load.

This process is known as self-discharge. Internal chemical activity never completely stops. Much like food slowly changing in a fridge, time alone leads to measurable change.

The important detail is that different battery chemistries discharge at different rates.

• Flooded lead-acid golf cart batteries typically lose around 3–5% per month at approximately 25°C (77°F). If temperatures increase to around 35°C (95°F), that figure can nearly double. After 3–4 months without recharging, voltage may fall below recommended storage levels.
• Under similar conditions, LiFePO4 golf cart batteries usually lose about 1–3% per month. Over time, that difference becomes significant.

What’s Considered Normal Voltage Drop? Here’s a reference:

• 48V lead-acid battery pack fully charged: ~50.9–51.5V
• After 1 month unused: ~49–50V (within normal range)
• Below 47–48V without use: caution zone
• 48V LiFePO4 battery fully charged: ~54.8V
• After 1 month unused: ~53.5–54V (within normal range)
• Unexpected drop below 50V without load: abnormal

If the voltage falls sharply within just a few days, that goes beyond normal self-discharge and indicates another issue.

What Causes Battery Drain When Not in Use?

If your golf cart battery is losing charge more quickly than expected, there are several possible underlying causes.

Natural Self-Discharge

As explained earlier, electrochemical reactions continue at a slow pace. In lead-acid batteries, gradual corrosion and sulphation occur internally. Lithium batteries are chemically more stable, which explains their lower self-discharge rate.

As batteries age, this process speeds up. For instance, a four-year-old lead-acid battery may self-discharge at 6–8% per month, particularly if it has been regularly deeply discharged.

Parasitic Drain (Hidden Electrical Draw)

Even when switched off, certain components may still consume power, including:

• Speed controller memory
• Digital display units
• Voltage converters
• Security or alarm systems
• Bluetooth modules
• Lighting connected directly to the battery

This phenomenon is known as parasitic drain. In most golf carts, standby draw ranges from 10mA to 50mA. While that seems minimal, over 30 days, a constant 30mA draw can remove approximately 21.6Ah from the battery system.

For a 100Ah battery, that equates to more than 20% of total capacity lost without driving at all.

Battery Management System (BMS) Standby Use

Lithium batteries incorporate a Battery Management System (BMS). This safeguards against overcharging, deep discharge, short circuits and temperature extremes.

Even in standby mode, the BMS consumes a small amount of current, generally between 5mA and 20mA depending on design.

Well-engineered systems, such as those used in advanced lithium golf cart batteries like Vatrer LiFePO4 batteries, are designed to minimise standby consumption. Lower-grade systems may draw more power, leading to faster storage-related losses.

Temperature Effects

Ambient temperature has a greater impact than many owners expect.

• At 0°C (32°F), lead-acid battery capacity can temporarily decrease by 20–30%
• At around -18°C (0°F), usable capacity may drop by up to 50%
• Above 35°C (95°F), internal ageing accelerates

Lithium batteries cope better with cold storage conditions, but charging below freezing without protection can cause damage. This is why quality lithium systems include low-temperature cut-off protection.

Temperature does more than reduce capacity; it also affects voltage behaviour. That explains why your battery might look dead in winter and then partially recover once warmed.

Aging and Sulphation (Lead-Acid Only)

If a lead-acid battery is left partially discharged for extended periods, sulphation begins forming on the plates. This reduces the active surface area available for storing energy, meaning the battery cannot hold as much charge as before.

For example, a battery that once provided 100Ah may now only deliver 70–80Ah after extended idle periods without full recharge. Lithium batteries, in contrast, do not suffer from sulphation.

Lead-Acid and Lithium Battery Storage Behavior

After only a few months of inactivity, performance differences between lead-acid and lithium batteries become noticeable.

Lead-acid batteries are particularly sensitive to partial charge states and prolonged idle periods. Without proper maintenance, their condition can degrade quietly.

LiFePO4 lithium batteries remain more stable during storage and are less likely to suffer permanent damage from sitting unused. They still self-discharge, but their chemistry is more resilient.

Lead-Acid vs Lithium Storage Comparison

Lead-acid batteries should remain fully charged during storage. Allowing voltage to fall below 12.4V per 12V unit increases sulphation risk.

Lithium batteries are better stored at partial charge. Keeping them at 100% for many months can slightly accelerate internal ageing.

This distinction directly affects how owners should approach winter battery storage.

How Long Can a Golf Cart Be Parked Without Being Charged?

The answer varies depending on battery chemistry, state of charge, ambient temperature, and whether the system remains connected.

As a precaution, disconnecting loads and selecting the appropriate storage method based on battery type and anticipated downtime is recommended.

For lead-acid battery systems:

• 2–4 weeks: generally acceptable
• 1–2 months: recharge advised
• 3+ months without charging: high sulphation risk

For lithium battery systems:

• 2–3 months: typically safe
• 6 months: usually safe if stored at 50–60% SOC
• 12 months: often recoverable if properly disconnected

If storing for more than 30 days, storage strategy should be adjusted accordingly.

For lead-acid batteries, using a smart maintenance charger (float mode) is recommended to prevent sulphation.

For lithium batteries, a maintainer is generally unnecessary if stored at 50–60% SOC and disconnected. However, a lithium-compatible smart LiFePO4 charger can be used for occasional checks. Ensuring charger compatibility with the battery chemistry is essential.

Signs Your Battery Is Losing Charge Abnormally

If discharge appears excessive or recovery after charging is poor, further inspection is required.

The key difference between normal and abnormal discharge lies in the rate and consistency. Healthy batteries lose charge gradually. Faulty ones behave unpredictably.

Watch for these red flags:

• Voltage decreases by more than 1V overnight
• Fully charged battery pack drops below 80% SOC within a week
• Difficulty holding charge after 2–3 days unused
• Noticeably reduced driving range after recharge
• Uneven voltage between individual 12V batteries (lead-acid)

Quick Diagnostic Table

If voltage improves slightly after warming during winter, the issue was likely temperature-related rather than battery failure.

How to Prevent Golf Cart Battery Drain During Storage

Avoiding unnecessary battery discharge during storage is straightforward, provided a few precautions are taken before leaving the cart idle for weeks or months.

Disconnect the Battery

Disconnecting the negative terminal or using the main battery isolator eliminates parasitic consumption from controllers, displays and accessories.

Store at the Proper State of Charge

Lead-acid batteries should be stored fully charged to limit sulphation. LiFePO4 batteries perform best when kept between 50% and 80% SOC during extended storage.

Use a Smart Charger or Maintainer (When Needed)

If storage exceeds 30 days, a smart float charger is recommended for lead-acid systems to maintain voltage without overcharging.

Lithium batteries generally do not require continuous charging. For long-term storage, periodic voltage checks using a lithium-compatible charger are sufficient.

Control Storage Temperature

Whenever possible, store batteries in environments between 5°C and 25°C (40°F–77°F). Excessive heat accelerates ageing, while freezing conditions reduce available voltage and complicate charging.

Check Voltage Monthly (If Possible)

Monitoring voltage monthly with a multimeter can help identify unusual discharge early. Sudden or significant voltage drops may indicate parasitic draw or ageing-related decline.

When Battery Drain Means It's Time to Replace

Sometimes discharge is not related to storage practices, but simply the end of service life.

If your golf cart battery:

• Is over 4–5 years old (lead-acid)
• Delivers shorter range despite full charging
• Loses 20–30% charge within a few days
• Needs frequent top-ups
• Shows visible corrosion or swelling

These are typical signs that the battery is approaching replacement.

Lead-acid batteries in European climates generally last around 3–5 years.

Quality lithium batteries often exceed 4,000 cycles, equating to approximately 8–10 years under moderate usage.

If discharge continues to worsen despite correct storage, internal degradation is likely underway.

Conclusion

Golf cart batteries naturally lose charge over time due to ongoing chemical processes. Temperature, parasitic consumption and ageing all influence how quickly voltage declines. Recognising these factors helps distinguish between normal behaviour and early signs of failure.

Lead-acid batteries require regular maintenance and full-charge storage to prevent sulphation, whereas lithium batteries provide greater stability and lower self-discharge during prolonged inactivity.

For owners storing their golf carts in unheated garages or colder European regions, lithium batteries with integrated low-temperature protection offer additional reassurance during winter lay-ups.

Vatrer lithium golf cart batteries incorporate a Battery Management System (BMS) working alongside temperature sensors to automatically halt charging below 0°C (32°F) and stop discharging below -20°C (-4°F). This coordinated protection system enhances operational safety and supports long-term battery health.