The majority of lithium polymer batteries used in radio control come with JST-XH balance leads - you can use this 30cm / ~12in extension cable to give you more length to put the batteries inside a lipo sack while charging -or- you can chop them up and fabricate your own balancing adapter.

Made with soft / super flexible 22awg silicone wire.

This extension cable comes in 2S, 3S, 4S, 5S, and 6S