Before purchasing a lithium battery pack, start by analyzing your power requirements. Decide on the capacity you need in order to charge your devices or provide power to your system which could either be in Wh or kWh. Make sure to check the provided output voltage and current to confirm compatibility. Check for battery packs with adequate safety measures against over charge, over discharge, and short - circuit protection. Also, consider brand reputation alongside build quality and warranty. In addition, ensure to consider prices from other sellers to acquire great value for your purchase