You’ve been driving along the golf course all day in your golf car, and as you head up the steep hill back to the clubhouse, it suddenly quits. This scenario has been reported to have happened when using some lithium-ion (Li) batteries. The reason, however, isn’t because Li batteries need more capacity or have run out of power. Instead, it has to do with the battery shutting down to prevent damage or overheating. It’s important to understand when and why this would happen.
When it comes to Li batteries, the overall run-time isn’t usually a concern as it is for Flooded Lead or AGM batteries. Li batteries stay at peak 100% power no matter if the load is 11 amps or 220 amps. When trying to make equal comparisons between Li and lead-acid batteries of the same size, the battery industry continues to use amp-hour (Ah) ratings for Li batteries in the same manner as they do for FLA and AGM. This can cause some confusion as overall capacity and run-time are determined by the Ah ratings based on an industry-standard 20-hour rate with the formula, (Ah=Current (amps) x Time (hours).
It can also get frustrating when golf car owners hear that some have switched from a 220 Ah lead-acid battery to a similarly sized Li battery rated at 30 Ah, and claim they can run their vehicles longer over a single charge.
So if the Li battery is always at peak power, it explains the difference in Ah ratings. But why would a golf car suddenly stop working? The answer is a dramatic change in the current draw on the battery. The current draw increases on a Li battery as the load increases to the golf car’s motor. Steep hills and heavy payloads require more current voltage for the golf car motor to keep up. This adds a greater current draw from the battery. When this happens, additional heat is generated from the Li battery cells as it increases relevant to the current draw. To prevent overheating and damage, the Battery Management Systems (BMS) in Li batteries can force a battery to shut down when the current draw causes the battery to reach a specified temperature.
The answer to consistent large current draws on your golf car’s Li battery is to add more current-draw capacity, as opposed to Ah capacity as in a lead-acid battery. Lithium-ion batteries can be connected in parallel to make up for constant peaks in current. For example, two 48V GC2 30 Ah Li batteries in a golf car can handle larger current-draw peaks, keeping everything running safely while driving over long steep hills or if your golf car is used for delivering heavy loads.
For those golf car owners who want to avoid adding extra cables and setup for multiple batteries, manufacturers also offer larger-sized 48V batteries that feature a 105 Ah rating and can handle greater current draw. According to Marvin Ho, VP of Research and Development at U.S. Battery Manufacturing, a single 48V 105Ah large battery is less expensive than adding multiple 48VGC2 batteries, wired in parallel, to your golf car. “This is simply because of the amount of case materials and the number of cells,” says Ho. “But each situation need is unique, and golf car owners should consult their battery dealer or manufacturer to get more information on the best way to increase current capacity if needed.” For more information on current-draw, amp-hour ratings and understanding the differences, visit www.usbattery.com.
