Ion Lithium Batteries have arrived and are available for any cart at additional cost. Charger replacement is usually required 
and budget 2500 to 5000 for this up grade depending on model and desired range.
Here are some key facts you can weigh.
1. Lighter weight by 50% to 75%
2. Smaller size package with standard capacity
3. Able to increase range and capacity
4 No water ever
5 Fast recharge in 2 hours compared to 8 hours for lead acid.
Video on lithium ion batteries does not work.