If you put into a search engine, "What makes a lipo be able to charge at such a high rate?", you'll get some good reading material. You might run into some manufacturer's bla, bla, bla LiPo cell formulation allowing higher charge rates. And then, you might run into a spec class racing thread where battery wars/speed secrets are sought-after. Some packs will have a printed charge rate on label. For years, a 1C charge rate has been "the norm" for safe charging and greatest longevity of LiPo cells. Sometimes I see/read that a 2C charge rate is said to be a great compromise between speed of charge/safety/pack longevity.