Main thing - Brand Name
batteries.
High Drain - 20amp or higher. 30amp is hard to find legit.
Keep the Pair together. Charge together.
My Nitecore - nice for charging up to 4
batteries at a time. 2 channels 1&3, 2&4
Each channel can quick charge a single or slow charge 2
batteries.
Good charging practice:
Let freshly spent batteries cool for up to 10 minutes before charging.
Let freshly charged batteries cool for up to 10 minutes.
This practice allows the batteries to internally stabilize(relax) and reduces load stress.(wear)