“How do I go about testing a golf cart battery?” is a question we are asked regularly at Golf Car Catalog. It is also a question for which there are lot of answers available online, most of which contain false or misinformed information.
First, all batteries are not the same. So, for the purpose of this discussion, we will stick to the common flooded cell lead acid batteries commonly used in gas and electric golf carts, electric vehicles, and utility vehicles. Testing other battery types such as AGM (Absorbed Glass Mat), Lithium, Gel or other battery chemistries may require specialized procedures which differ than those outlined here for lead acid varieties.
Let’s provide a basic understanding of what batteries are, what they do, and how the behave. A battery is defined simply as two dissimilar metals immersed in an acid. A battery does NOT store electricity as most people think, but rather is able to produce electricity as a result of a chemical reaction which releases stored potential chemical energy in the form of electrical energy.
As a golf cart battery ages, its capacity get reduced over this time. Capacity describes the time that a battery can continue to provide its intended amperes from a full charge.
With the basics covered, let’s move on to how to test golf cart batteries as well as possible symptoms which could indicate a battery issue. Of course, for proper battery maintenance, always check your electrolyte levels in each cell and water as needed. Please refer to our article “All About Batteries” for proper maintenance procedures. In addition, neutralize and clean all corrosion from the battery tops, caps, terminals and cables on a regular basis. A little bit of preventative maintenance can go a long way to prevent issues with your golf cart’s batteries.
Possible symptoms of a failing battery or batteries could include the following:
- “Shuttering” in an electric golf cart is a classic sign of low voltage. If this is experienced, your cart may be low on charge, the charger may not be functioning properly or you may have a battery issue.
- Of course, if the golf cart doesn’t start and/or move, this could indicate a battery issue on either gas or electric carts. If your gas golf cart won’t turn over at all and try to crank, check your battery voltage first. Most electric golf carts will not run if the voltage drops behind a pre-programmed level.
- Most fully charged modern electric golf carts with “good” batteries should be capable of running for at least two full rounds of golf per charge. If you find that suddenly, your range has been significantly decreased, you could also have a battery issue. With proper care and maintenance, depending on cart usage, load, and terrain, most lead acid golf cart batteries last an average of 4-6 years.
The first method of testing a golf cart battery is to use a hydrometer, which measures the density of the electrolyte through a specific gravity reading. Specific gravity is always compared to a baseline density of water, which is 1.000. The concentration of sulfuric acid to water in a new golf cart battery is 1.280, which means it is 1.280 times the weight of the same volume of water. A fully charged battery will test around 1.275-1.280, while a discharged battery will read in the 1.140 range. Specific procedures for using and reading your hydrometer can vary between brands and should be derived from the hydrometer packaging instructions.
The second method of testing a golf cart battery would be to use a load tester. With more than 35 years of experience at our local shop, we have found that this testing method will often provide a more accurate result in a shorter amount of time. A battery load tester is a simple DC heating coil which is connected to a volt meter. When connected to a single battery, it displays the voltage of the battery. There is typically a button to depress and by doing so, you complete a circuit for the heating coil, causing it to produce heat from resistance. This applies a load to the battery. Watching how the voltage behaves under this load can provide insights into the health of the battery. A good fully charged battery should only drop about .2-.4 volts under the load and hold at that level. Any voltage drop observed to be greater than about .5 volts could indicate a failing battery. Often, this load test is more likely to show a bad battery when the batteries are relatively discharged than if they were full. Occasionally, only one or two batteries fail prematurely in comparison with the rest of the batteries in the bank. Be sure to check all batteries individually in this process to eliminate all possible failures.
The last method of testing a golf cart battery would be to use a discharge machine. They are often expensive and not practical for home use, but most dealers have one. The discharge machine connects to the main positive and negative leads of your battery bank and has a heating coil as with the load tester to provide a 75 amp load across the bank during discharge. The machine will tell you a number, in minutes, of how long the golf cart could run under a typical load of this level before 75% depth of discharge is achieved. For example, a good, fully charged 36V set comprised of six 6V Trojan T-105 batteries (or any other brand), should be capable of discharging around 105 minutes or so, thus the “105” moniker. If you find that your discharge time is only 50-60 minutes, you are likely approaching the end of life for your battery bank.
Written by Michael D. Williams, Product Development Director (www.golfcarcatalog.com)