I have a new blade and I have a socket on the left of the seat is this for diagnosis or to plug in my optimate as it does fit???? all new to me...
If its just 2 pins and meters around 12.7 VDC or lower depebding on batt charge, then its connected to your battery.
If it has two wires and is white it may be a tamiya connector. If it is black then it could be an SAE connector. Google them and you should get pics to compare against yours. If it is round then it may be a headset connector. Could be anything from a single hole to 5/6 inside it for intercoms cables.
Looks like a Tamiya but weatherproofed in rubber with a cap, my optimate charger fits it just making sure it is what I think it is? will try to get a pic