When it comes time to purchase a new set of deep-cycle, flooded lead-acid batteries, golf car fleet managers look for ways to save money. With many golf cars requiring 48 volt battery packs, one of the most common money-saving assumptions is that purchasing fewer batteries with higher voltages will be a less expensive alternative. For example, a typical 48-volt golf car may use eight 6-volt batteries, six 8-volt batteries, or four 12-volt batteries. Purchasing fewer batteries with a higher voltage is appealing because it reduces your upfront cost. However, the pack configuration should be based on a few more factors.
The example below shows a comparison between three different packs utilizing three main battery voltages. As the table shows, the 6-volt system has a higher capacity than the 8-volt and 12-volt systems. A typical round of golf will require about 40 minutes of runtime while discharged at 56 amps. With all three configurations, the batteries have more than enough capacity to get through two rounds.
However, one thing to keep in mind is the effect of depth of discharge (DOD). A battery’s DOD is defined as the capacity taken out of the batteries as a percentage of its overall capacity before recharging. The lower the depth of discharge in lead acid batteries, the greater number of cycles they will deliver. Theoretically, a battery that is routinely discharged to 30 percent DOD will last about 2.2 times as long as a battery that is discharged to 60 percent. With the 6-volt and 8-volt systems, a day’s worth of golf car use discharges the battery pack to a lesser extent. This can reduce your overall operating cost in the long run, by yielding greater cycle life and ultimately extending the time between replacements.
The pack configuration that fits a given application can be determined by weighing upfront costs, battery capacity, and cycle life. The price points listed below show that an 8-volt and 6-volt pack costs roughly 13 percent and 37 percent more than a 12-volt pack respectively. Although the initial cost is greater for the 6-volt and 8-volt packs, these configurations give a much greater return on investment*. Armed with this information, you can make a better decision on which battery configuration truly gives you the most cost savings.
*Vehicles utilizing regenerative braking and the use of opportunity charging can reduce the depth of discharge and extend cycle life.