The EXL Series of battery packs provide longer runtimes than the standard XL battery packs due to their higher VAh ratings. The EXL series does not have internal chargers in the connected UPS. However you can use a combination of XL and EXL battery packs to reduce the recharge time of the EXL battery packs while providing a more flexible runtime solution. (Example: your application requires 2 hours of runtime and the EXL battery pack selected only provides 1.5 hours of runtime.Instead of using two EXL battery packs, which will provide three hours of runtime, you can use the EXL along with an XL battery pack to provide the other 0.5 hours of runtime. This flexible solution not only saves you money, but also speeds up the recharge time of the EXL battery packs.