I received two NEU 4S1P 3900 mah 25C/50C lipo packs today and after putting some EC3 connectors like I did for my other lipos, I tried to charge them with my CellPro 10S charger and I get an error message saying ''reverse polarity''. My connectors are installed correctly, positive and negative where they should be. There's something I'm missing and I don't know what. I emailed NEU about it and am waiting for a reply so I thought of asking the experts here. Can it be possible that the red positive and black negative wires of the lipos are soldered to the wrong tabs underneath the heat shrink? I don't want to mess with it until I'm sure.
Here's one of the EC3 connectors I installed
And here is the balance tap I use.
What am I doing wrong?