There are a couple of variables to consider, such as- if the AED is monophasic or biphasic (referring to current and whether it is an escalating shock or a fixed energy shock), the patient's transthoracic impedance (variables of patient chest size), and patient's response to shocks. Therefore, it's good to know the 'use time, or general amount of shocks that can be delivered' with a specific AED and it's battery component.
Typically, the batteries used for AED are long life Lithium batteries which last approximately 4 years when the AED is in stand-by mode. Each manufacturer's specifications are different, but generally, when the AED is in use (with fresh Lithium batteries), that equates to up to 150-300 shocks or 720 minutes of use time.
So, really, it depends upon the manufacturer of the specific AED you are using, and of course- the manufacturers can provide specific information.
In any case, with a standard AED, it will be able to deliver all the shocks needed during such an event.