Is there an AC/DC charger that will charge at 12a and discharge at 10a? Trying to carry less things to the track.

No, that discharge rate is incredibly high for a charger - you usually have to go to a dedicated discharger to get anything over a few amps, especially with 2S and above. Most chargers will claim 10A discharge capable, but they are power (watts) limited. Check the max watts and divide by your voltage to see what it can actually do.

there is no such thing on the market. AC/DC chargers must have an internal power supply which severely limit their power out put. There are many ac/dc charger than can charge at well over 12 amps but none can discharge at anything close to 10amps.

the most powerful AC/DC charger that I know of would be the skyrc d400 which has 400watts of charging power and a max of 36watts of discharge power per channel. So you can charge a 1s-4s lipo at 20amps no problem but at only 36watts of discharge power you can on discharge a 4s lipo like at 2amps and a 2s lipo at 4amps. Also 36watts of discharge power is more that most other ac/dc chargers.