Yes, 2C is their standard max charge spec on any of the f3a sized batteries I've looked at, regardless of the discharge C rating. Doesn't matter if it's their 20C or 45C rated packs like at the links below. A nearby Thunder Power sponsored, top F3A pilot says he only charges at 1C, period, and recommends that if you want any longevitiy out of packs that's key and has a lot of his own data over the years to back his conclusion. I've seen him field charge and that's all he does. He's a name anyone in pattern will know and respect so take that for what it's worth. You buy the expensive packs and want them to last, baby the charge rate and fly often, don't let them just sit around.

https://www.hobbyking.com/hobbyking/..._5S1P_20C.html

https://www.hobbyking.com/hobbyking/..._5S1P_45C.html