RC battery help

Hello all, I am in a bit of a predicament with a new battery I recently purchased for my RC quad motorcycle; it's a 7.2V battery pack and I'm using the charger that came with the motorcycle itself (purchased it about 6 years ago and haven't used it since the old battery pack died about 3 1/2 years ago) and the charger's underside says "15-minute universal charger." Should I listen to the 15 minute thing or since it's a new battery let it charge for about 8 hours (i did the math and thats how long it should take to charge). I realize that this is an RC CAR subreddit but the overarching theme of of this sub is RC so yeah, if anyone could please give me advice or suggest what to do that would be awesome! Thanks