A battery’s “C-rating” is a reference to the maximum amount of continuous current it can deliver. The rating is expressed as the battery’s capacity (that’s what the “C” stands for) multiplied by the rating number. For example, if you have a 5000mah, 25C battery, the math is 5000 x 25 = 125,000 milliamps, which we can divide by 1000 to get 125A. This battery can handle continuous current draw up to 125A. The larger/heavier/more powerful your vehicle, the more you need a battery with a higher C-rating. Smaller/lighter/less powerful models can use packs with lower C-ratings. But here’s the thing: C-ratings are not consistent from brand to brand, so Brand A’s 25C battery may actually be able to handle more current than Brand B’s 40C battery. If you’re comparing batteries of the same brand, you can be sure the pack with the higher C-rating can handle higher current draw than the pack with the lower C-rating. If your vehicle’s manual recommends you use batteries of a certain C-rating, shop accordingly.
Larger, heavier models like this Arrma Outcast monster truck are best powered by packs with higher C-ratings.
After capacity, C-rating (here, 50C) is often the most prominent number on a Lipo pack.