How to Tell If a Golf Cart Battery is Bad

Power - by Bryan Veldboom - updated on 9/4/2023

line of parked golf carts

So there you are, zipping along in your golf cart when all of a sudden the power cuts out. You know you charged the batteries last night, so what happened? Sounds like you have a bad battery on your hands. If you find yourself in this situation, Batteries Plus can help. You'll find a full range of replacement golf cart batteries both in-store and online. Before you can do that though, you need to figure out which golf cart battery is bad. Here is a step-by-step guide to help you do that.

How Many Batteries Does a Golf Cart Have?

The first thing you need to determine is what type of golf cart you have. This is important in order to determine the number and type of batteries you have in your cart.

Gas Powered Golf Carts

Use only a single starting battery similar to the one in your car.

Electric Golf Carts

Run on several deep cycle batteries.
Electric golf carts have different voltage requirements, including 36V, 48V & 72V carts.
Lead acid golf cart batteries are available in 6V, 8V and 12V options. In addition, there are 36V and 48V lithium golf cart batteries.
The average electric golf cart requires four to six batteries, but may have as many as twelve separate batteries.

How Do You Know When Your Golf Cart Needs New Batteries?

When a battery reaches the end of its lifespan, its performance will begin to drop, which will lead to one or several of these symptoms:

The batteries take longer to charge.
Your golf cart doesn't last as long as it used to.
Your golf cart won't accelerate as quickly as before.
A battery is leaking or features noticeable bulges on the casing - if you notice this, the battery must be replaced immediately.

How Do You Test a Golf Cart Battery with a Multimeter?

For our purposes here, we'll be focusing exclusively on electric golf carts. Since gas powered carts have only one battery, it's easy to determine which one is malfunctioning. If you want to be sure your issues are battery-related you can test your starting battery using these steps or by having it tested at your nearest Batteries Plus.

Since electric golf carts have multiple batteries onboard, determining which one is bad requires a little more work. If you're wondering how to tell which golf cart battery is bad, you can figure this out by testing all of your batteries using a multimeter. To test your deep cycle batteries, follow these steps:

Make certain that you are performing the test in a well-ventilated area. This is important because batteries can give off harmful gasses.
Always wear protective eye, face and hand protection when charging or testing a battery.
Fully charge all of the batteries and let them sit for at least an hour disconnected from the charger and golf cart before testing them.
Turn on the multimeter.
Set the multimeter to the "voltage" setting.
Connect the multimeter leads to the batteries' terminals, with the red going to the positive terminal and the black lead going to the negative terminal.
Read the voltage.

What Should a 12 Volt Golf Cart Battery Read When Fully Charged?

A fully charged 12-volt deep cycle battery should have a voltage of 12.7 volts or higher. If your battery tests at around 12 volts or lower, your battery may need to be replaced.
A fully charged 8-volt deep cycle battery should have a voltage of 8.4 volts or higher. A reading of 8 volts or lower, indicates your battery could be bad.
A fully charged 6-volt deep cycle battery should have a voltage of 6.3 volts or higher. A reading of 6 volts or lower, indicates your battery could be bad.

How Do You Test a Battery with a Hydrometer?

Using a multimeter is a fast and easy way to test a battery's voltage, but there are other, more accurate testing methods. If you have a flooded golf cart battery, you can use a hydrometer. A hydrometer is a tool resembling a syringe with a glass float inside, which is used to test the specific gravity (its weight compared to water) of your battery's electrolyte solution. The experts at your neighborhood Batteries Plus store can perform a hydrometer test for you, or you can pick one up yourself and follow these steps:

Perform the test in a well-ventilated area.
Always wear protective eye, face and hand protection when testing a battery.
A hydrometer should only be used on a flooded (wet) battery. Do not attempt to use a hydrometer on an AGM or other fully sealed battery.
Make sure that the battery is fully charged before testing it.
Do not take a hydrometer reading right after you have added water to the battery. The water must have enough time to thoroughly mix with the electrolyte in order to provide a true reading.
Remove the caps to reveal the battery's cells.
Place the hydrometer's nozzle into the battery's electrolyte and draw some of the liquid into the hydrometer's bulb. Draw the minimum quantity of electrolyte into the hydrometer to permit the float to float freely without contacting the top or bottom of the cylinder.
When reading the hydrometer, be sure you are holding it vertically so that the float is not rubbing against the side of it.
Test each cell and note the readings (corrected to 80°F or 27°C). A variation of fifty points between any two cell readings (example 1.250 and 1.200) indicates a problem with the low reading cell(s).
As a battery ages the specific gravity of the electrolyte will decrease at full charge. A fully charged battery will normally test at 1.275 - 1.280 while a discharged battery will read in the 1.140 range. This is not a reason to replace the battery providing all cells are within fifty points of each other.

How Do You Load Test a Deep Cycle AGM Battery?

In an AGM battery, the electrolyte is absorbed and held in a special glass mat. This makes it impossible to perform a hydrometer test. If you're looking for a more accurate method of testing an AGM golf cart battery, you'll want to perform a load capacity test. Performing a load test requires special equipment which most people aren't likely to have.

Fortunately, there's an easier way. Simply take the battery or batteries to Batteries Plus and ask them to perform a capacity test for you. This will let you know for sure if you need to replace them. Be aware that performing a capacity test may take around 20 hours to complete, so be prepared to leave your battery or batteries overnight. If they cannot perform a capacity test, they will perform a crank load test. This will also provide you with a good assessment of your battery's condition.

Why Do Golf Cart Batteries Go Bad?

Here are some of the most common reasons why a golf cart battery fails:

The Battery is Too Old

A golf cart battery can last between four and six years.
If your battery is older than that, you can expect that you'll need to replace it soon.

The Battery Has Been Overcharged

Overcharging a battery can kill it prematurely.
When selecting a battery charger for your golf cart, be sure that the model you select is compatible with the voltage of your batteries. For example, if you have six 8 volt batteries in your cart, you'll need a 48 volt charger.
The charger must be also compatible with the chemistry of the batteries you have, which will be flooded (wet cell), AGM (Absorbed Glass Mat) or lithium iron phosphate.

The Battery Has Been Undercharged

When a battery remains undercharged for too long, it can lead to battery sulfation, which will impede the flow of the battery's current.
To avoid this, be sure to fully charge your golf cart batteries every time they drop to 50% of their total capacity.

The Battery Terminals are Corroded

There are many causes of corrosion. One of the most common occurs when acid vapor interacts with the terminals.
Corrosion can also occur if the electrolyte in a flooded battery gets too low. If you have a flooded battery, be sure to check the electrolyte levels frequently and top off the liquid inside with distilled water when the plates become exposed. For tips on this see our blog entitled "Does My Battery Need Watering?"
You can clean corrosion off of your battery's terminals using a mixture of baking soda and water and a wire brush. Afterward, apply an anti-corrosion spray to prevent corrosion from returning.

Batteries Plus Carries Replacement Golf Cart Batteries and More

Want to learn more about golf cart batteries? We have plenty of additional information online. Take a look at our Golf Cart Battery Buying Guide, or check out our blog. Some related topics include "Understanding Golf Cart Battery Basics" and "How to Install Golf Cart Batteries."

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