RE: Brushless Rancho
8xl dont ask for much amp so you can use any fine lipo over 4500mah with 20-25C discharge rating. i use 4500Mah 20C Broadamp and they go good.
depending on your budget you shall get the highest C rating you can=25C and highest amp battery you can afford.
More technical info:
4500mah X 20C = 90 Amper/hour
4500mah X 25C = 112,5 Amp/hour
5000mah X 20C = 100 Ah
5000mah X 25C = 125 Ah
8XL will use around 20-25 Ah avarage and you'll get about 20 minutes of runtime. if you use small pinion your runtime will be more, if you use big pinion your runtime will decrease but speed will be much more.
also at acceleration your motor will draw high amp like 70-80 ampers.
The higher C rating and higher mah value and the better battery quality will mean longer runtime, longer lifespan of battery.