A vehicle with stop-start will use a different type of battery. A stop/start system shuts off your vehicle while stationary to save power, this tech is designed to reduce fuel consumption and CO2 emissions. But vehicles with start-stop tech place a greater demand on a vehicle’s battery – so it'll have an AGM or EFB battery rather than a conventional acid flooded lead battery.
This means you’ll need a smart charger to charge these types of battery safely. However, some battery chargers don't state that they're start-stop compliant, but they still are. For example, the CTEK MXS 5.0 and all CT5 products are compatible with all 12V lead-acid batteries, including AGM & EFB batteries. I wouldn't recommend using a very old bit of kit on a new car, although if it's still in good working order and is compatible then you might find it's still okay to use. You haven't told us what it is, but a quick Google search should give you some idea of whether it's suitable for start-stop vehicles.