B&B Batteries

I am the owner of two 24 V ebikes. We have not used them over the last three years and have just pulled them out to get them ready for the summer. Do you know of any options for battery replacements than the lead acid batteries. They are so heavy and I can't imagine that there isn't a better solution for this now. If you can give me any suggestions, I would appreciate it.

Thanks,
Lorna Doone