What does the term "cycle life" mean when you're talking about electric car or golf cart batteries?
Hi, good question.
It's the number of times a battery can be discharged and recharged until it will no longer take a charge. A battery like the Trojan T-105 is reputed to have 750 full charge/discharge cycles in its life.
Does this REALLY mean discharging all the way? No. Lead acid batteries don't like to be fully discharged, and they will respond with a nasty drop in cycle life.
Does this mean every time you charge the battery, even if it's only been run slightly, that it counts as a cycle? No. There's an equation for this that escapes me at the moment, but there's no "topping off" penalty, contrary to popular belief. Lead-acid batteries prefer to be topped off, not run down fully before recharging.
Does this mean every golf cart battery has about 750 cycles, more or less? No. And not every T-105 will perform that well, either. There are plenty of things that affect cycle life that make it really hard to predict just how many cycles you're going to get out of your battery pack.