Try Proterra out to see if it is a good fit. First bus has ALTI batteries. Second bus has (below)

Proterra’s first all-electric Catalyst bus, fitted with advanced lithium titanate oxide batteries and a fast-charge energy storage system, reached the U.S. market in 2010. In the first quarter of 2015, the company added an extended-range version fitted with lithium nickel manganese cobalt oxide (NMC) batteries.

http://articles.sae.org/14386/