For this section, I am going to dumb it down as much as possible for those just trying to get the gist of the bare minimum knowledge, they need to make a choice. To choose the right battery for you, you need to decide what is important to you. Batteries are based on what follows.
Range. Arguably the most important factor on the battery you will decide. The range is dependent on the Watt-hours (whr, WH, watthour, etc.) your battery contains. The typical rider will average 20-27 whr per mile, with the hardcore riders pushing up into the 30s. That means if you choose for example the CBGT pictured above which has 550.8 whr/mi that the average rider would see 20.4-27.5 miles of range (550.8 divided by the average whr per mile).
Weight. The weight is a much less pertinent factor when it comes to choosing your battery but one worth mentioning. A general rule of thumb is smaller cells will weigh much less (ie. the 18650 packs that are typically made for stock XR boxes). With batteries being the second heaviest thing in your board it can be important to shave off some weight for some, especially those who carry their board (who does that).
Speed. Speed is directly correlated to voltage. If you are an absolute speed demon you may want to go for a higher S count build. now by no means is 15s slow, but your average VESC rider will lean towards 18s or 20s for that extra Oomph.
Important Notes:
If you are re-using the stock harness, please note that the stock harness’s XT-60 (along with the stock BMS and battery) is wired in reverse. This means if you are using an aftermarket battery which uses the correct polarity on the the XT-60’s, you have a problem. Be sure to double check polarity, always.