Li-ion 21700 Battery Pack Case Holder 6s 4s & 3s

If you're looking to build your own lithium-ion battery packs, here’s what I’ve been using with great results. Just a heads-up: the 4S and 6S rectangular-shaped versions may feel slightly loose depending on the brand of cell you choose, as cell dimensions can vary. I designed these packs to be universally compatible, but if you prefer a snugger fit, consider scaling the design down by 1–2%.

⚠️ Important Warning Just like 18650 flight packs, 21700 cells aren’t suitable for everyone. Always stay within the specified limits of the battery to ensure safety and performance.

🔋 Choosing the Right Battery for Your Needs What’s your goal with these packs? If you're aiming for high-speed racing, these batteries aren’t ideal. But if you're focused on managing amp draw and maximizing flight time, they’re a fantastic choice. Selecting the right 21700 cells for your application is critical.

Personally, I use the Molicel 21700 P42A – 4200mAh, 45A cell: 👉 Molicel P42A on 18650 Battery Store

🛠️ My Build Example Check out how I used these cells to achieve over 25 minutes of flight time on a 7" quad: 👉 My RotorBuilds Page

🔧 Assembly Tips If you're assembling the packs yourself, I recommend using a spot welder to minimize the risk of overheating and damaging the cells. For higher amp draw applications, consider soldering ½" wide copper grounding braid straps instead. These handle current better than standard nickel-plated strips, which can overheat and fail under stress.  👉  Copper grounding braid straps

📺 Safety First Please take time to watch tutorials on YouTube about proper lithium-ion battery handling. Safety is non-negotiable when working with these cells.