Originally Posted by Davemac122383

They also sell other wires that can connect to that plug, im pretty sure its called a SAE connection. I have wires to connect to for my phone charger, ipod (USB) and you can also use it for heated gear.

Originally Posted by Imold

Some brands (Noco is one) use non standard or proprietary connectors, but usually sell an adapter plug or short adapter cable for use with SAE connectors (again, Noco does). I don't recognize the one in your pic, but if you do a search for your brand tender and accessories, you might find an SAE adapter. Then, if you wanted to plug something else there, you could replace that one with an SAE cable. I made a 10 awg SAE cable so I could plug both my tenders and lithium jump starter battery to it, using adapters for the ones that weren't SAE. Might sound complicated, but it wasn't really, and I like having just one extra cable to put on the battery that handles everything.