If they'll work long enough to test, I'd hook up 2 forklifts for charging & test input & output of chargers. I'd then swith the forklifts & test again. If they're blowing fuses, they're either getting insuffecint power or putting out to much. This test will give you a directrion to follow.
This is ONLY to be used to report flooding, spam, advertising and problematic (harassing, abusive or crude) posts.