luthj
Engineer In Residence
I'm not 100% certain but I believe the data cables are for the Battery management system (BMS), not for the battery voltage. If you watch the video above you'll see that he connects the data cables but he ALSO connects the batteries together at the terminals using standard battery cables like you would with any other big battery. In the video he is connecting them in parallel, don't know why you COULDN'T connect them in series, I suppose, if you needed a 24v battery for some reason. Why would you need higher voltage than 12?
Thats what I was trying to convey. If the batteries are aware of each other, then can use there internal balancing circuitry to bypass current around the entire battery, allowing the others time to equalize. Typically the BMS in these units can only bypass individual cells internally, as it has not idea what other batteries in the string are doing.