You neglected to provide a link to the battery, which I can tell you now is not a 15A battery - there's
no such animal.
15Ah is entirely plausible, that's the capacity rating, not a current rating.
The load is 38 ohms, so as indicated above you have about 0.6A to switch, even a 2N2222 BJT can
just about do that (with a 150 ohm base resistor).
A logic level MOSFET or a darlington are better options (less close to the package heat limit,
especially with a heatsink).
What you will need also is a 1A fuse to protect the wiring and battery in event of a short circuit -
this goes inline with the battery +ve terminal usually, close to the battery. Your 6S LiPo pack
(guessing from the 22.2V rating) is capable of perhaps 100's of amps on a short, this is a fire
hazard and you must protect against this in unattended equipment.