I use the 800 mA EFlite charger that came with the BCPP to charge the 2250 mAh battery for my MX400, you will use a similar battery in the TRex. Almost 3 hours to charge, but I believe that it is better for the battery, and it takes _me_ at least that long to repair, I mean recover, from the 12-15 minute flight.

If you try to use the 800 mAh EFlite battery in the TRex you will kill the battery pretty quickly, it can't sustain the current drain required.

This 2250 mAh battery has a compatible charge connector on it. But you can make/buy adapters depending on what you have and need.