12.5 volts seems very low for a lithium ion battery. I would start with the battery. Here is Shorai’s charge vs voltage chart.

I recommend you contact Capuride. They may have a firmware update that helps with your issue. They do not post updates on the internet for download but will email you an update if there is one available.

I have contacted them twice for issues with another model Capuride and in both cases they ...