Had Harris batteries on my 2017 until this morning. Mine had a date of 5/16 so Thor was still getting new ones. Now I have 2 6V Interstates. Harris batteries lasted 8 months. They wouldn't take a charge - 12.6v to 19.1v in 4 days with no load.
Given the various posts I've seen about Harris not honoring warranties I didn't bother trying to get them replaced...with the same. Time, cost of driving 50 miles to CW and the hassle with them did not make it worth even trying. I also changed out the WFCO converter with a Progressive Dynamics.