Combine the oil, garlic, and thyme leaves in a large baking dish. Zest and juice 1 lemon and add to the mixture along with the salt, pepper, and onion powder. Mix well. Add the chicken, turn to coat, cover, and refrigerate for 2 – 8 hours.

Prepare grill for direct and indirect heat and preheat to medium. Brush the grates with oil.

Remove the chicken from the marinade, place skin side down on the grill over direct heat. Grill for 15 minutes or until the skin is golden and crispy. Flip and grill over direct heat for 4 – 5 minutes, move to indirect side of grill, cover the grill, and cook for another 15 minutes or until the chicken reaches a temperature of 160 degrees. Remove from the grill, cover loosely with foil, and let rest for 10 minutes.

Cut the remaining two lemons in half and grill flesh side down until charred, about 5 minutes.

Serve the charred lemons with the chicken.