polarity

GregChris

Getting ready to dry camp for 4 or 5 days. I got a sae pigtail  for my solar panel controller, and my charger for my gen has a sae adaptor. Both of them needed the polarity reversed to plug into the tub on my 2021 320s. is this normal? Should I be concerned? obviously an electric novice. Thanks.

SLJ

Had to reverse mine going to my RV battery systems SAE port. Used an adapter until I changed the connectors going to the solar panel on the pigtail. Always check with a meter. Never trust the wire color.

GregChris

Thanks

pthomas745

The issue will be: if the big metal part of the SAE cable is carrying the positive charge from the solar or the generator, you have the possibility of creating a short circuit or sparking.  The SAE is not "reversed" in any way.  It is designed to protect from the short circuit possibility by keeping the positive side of the cable safe inside the plastic cover of the plug.

If you need to use an adapter, use it.  Test your SAE cable with a multimeter. 

Horigan

In general the SAE connector is designed to have the positive side protected in the female contact.  However, when connecting solar to a battery, both sides have a hot positive, so one will have the positive contact in the exposed male pin.  Ensuring this happens may require "reversing" the wiring.  As @pthomas745 says, confirm with a multimeter before connecting.

rfuss928

Just to possibly add a bit of confusion to some folks efforts to understand electricity:
The positive wire from solar panels or any "external" (not connected to the trailer) power source is not a source of spark or shock unless that source's ground is also connected.  Think of it like your holding any standard dry cell battery.  Either end can touch any part of your trailer and nothing will happen.  Both poles of the source need to be connected to complete the circuit.  Mechanics learn to connect the positive side of the battery first so there is no spark danger if your wrench bumps any of the grounded metal all around.  Then you connect the battery ground to the vehicle with only the positive terminal to worry about.
The point is:  There is no concern wiring your solar with the positive on the exposed SAE male pin.  This will mate with typical vehicle battery SAE connections with the positive on the covered female terminal so it can't bump anything grounded on the vehicle.