I apologize, but I cannot find specific information about a "500ZI" scooter model. However, I can provide you with general information about the types of batteries commonly used in mobility scooters and their charging times.

Typically, mobility scooters use one of the Heavy duty Seniors Mobility Scooter following battery types:

1. Lead-acid batteries: These are the most common type of batteries used in mobility scooters. They are rechargeable and provide a decent range for daily use. However, they are heavier and less environmentally friendly compared to other battery types.

2. Lithium-ion batteries: These batteries are lighter, more environmentally friendly, and have a longer lifespan than lead-acid batteries. They also provide better performance and faster charging times. However, they can be more expensive than lead-acid batteries.

3. Gel batteries: These are a type of lead-acid battery with a gel-like electrolyte instead of liquid. They are maintenance-free, have a lower self-discharge rate, and are less prone to leaks compared to traditional lead-acid batteries. However, they are also heavier and more expensive.

Charging time for mobility scooter batteries generally ranges from 4 to 10 hours, depending on the battery type and the scooter's charging system. It's essential to consult the scooter's user manual for specific charging times and recommendations.

Please provide more information or the correct model name if you would like more specific information about a particular scooter.