I recently picked up an Irontron 12v Battery load tester from Northerntool. https://www.northerntool.com/shop/tools/product_200611634_200611634
It will test from 200 amp to 1000amp but only in increments of 100. The battery I'm testing is 340. My guess is that I'm supposed to set it at 300 or 400 but I don't know which. It's digital.
Thanks