I'm not new to DC in cars and electronics, but I am new to solar. The fact that I keep blowing fuses when connecting this charge controller to the batteries has me questioning my process, and I'd really appreciate some help. The (two) batteries are in an RV, relatively new, wired in parallel, both 12v, same exact manufacturer and type, and there are no (known) issues with the DC in the RV. I'm attempting to use the built-in wiring for connecting solar to the RV and have confirmed which wires are connected where, because sometimes they're installed wrong. There's nothing else connected to the RV or to the charge controller, no PVs, no other charge controllers, no other solar, no shore power, no generators, etc.
I insert the positive wire from the battery into the charge controller and tighten it down, and as soon as I connect the negative wire from the battery to the charge controller, the fuse blows. I've tried multiple fuses in 5 amp increments, right up to 50 amps, but they all blow. I've also bypassed the built-in solar connector, so the positive cable is going from the battery to the fuse holder and then from the fuse holder to the controller and the negative cable is going from the battery to the controller.
Am I doing anything wrong in the way I'm connecting and wiring everything? Other people who own the same make of RV have done this, without issue.
Final(?) Update: Amazon didn’t ship the new one, so I decided to try another charge controller that I intended to use for a different project. It’s a different brand, and is rated at 100/40. I connected everything in the exact same way as the Victron, and it just worked; no blown fuses. I’ll be sending this one to the supplier for replacement.
