I had quite a lengthly Facebook Messenger conversation with EAE about their battery system. One thing he mentioned is that through Sunburst Gear they had an external battery unit for EAE and Sunburst Gear amps called the MPB1. That has been discontinued and will be replaced with a new lithium ion version that will give about four and a half hours of play time after a two hour charge. Here is a link to a description of the discontinued lead acid battery version:
https://www.wiredathome.com/sunburst...ries-speakers/