I want to lengthen my charging leads to 2 feet, maybe 3. I only charge 2s and 1s packs at 5amps.

What gauge wires do I need? My charger is good for 6S/10A/250W so I'd like to get wires that could handle those numbers.

Your charger probably has 14-16AWG wires on it at most (probably closer to 16). Take the charger to wherever you are getting your wire and match it up. You can only push 10A max out of the charger, so there is no need to go overboard with heavy wire.

12 gauge is probably what you want, just to be safe. You could likely get away with 14, though. A nice 12V wire sizing table can be found here: http://www.affordable-solar.com/wire.charts.htm

For lower voltage, you need thicker wire, for higher voltage, you can get away with thinner wire. The chart says 10A can be done with 12awg at 12V for 7 feet with only a 2% loss. Halve that distance for 6V, leaving you 3.5ft.

You'll be charging a voltage somewhere in between, so 12ga over 3 ft should be more than adequate.

Note: I used 10A as the example because that's the max of your charger, which you should size for now, even if you're not using it. Then you won't have to make another harness again down the road. Wire is relatively cheap anyway.

Ok thanks. I'm going to go with TQ 13 gauge.