The Molicel P45B earned its reputation as a high-drain 21700 for packs that need punch. The Reliance RS50 is the cell inside every Hyperflux Black Series pack: more capacity, higher continuous current, and a published datasheet we actually build to.
Side by side
| Reliance RS50 | Molicel P45B | |
|---|---|---|
| Format | 21700 | 21700 |
| Typical capacity | 5000 mAh (min. 4950) | ~4500 mAh |
| Nominal voltage | 3.6 V | 3.6 V |
| Energy (cell) | 18 Wh | ~16.2 Wh |
| Weight | ≤ 67 g | ~70 g |
| Continuous discharge | 70 A (80 °C cutoff) | ~45 A |
| Charge voltage | 4.20 V | 4.20 V |
| Discharge cutoff | 2.5 V | 2.5 V typical |
RS50 figures are from the official INR21700-RS50 datasheet. P45B figures are typical published values — always check the sheet for the batch you buy.
What that means on a pack
A 6S1P RS50 pack is 108 Wh at ~445 g with 70 A continuous. The same layout in P45B is roughly 97 Wh and ~45 A continuous. You lose both energy and headroom. For long-range and cinematic FPV, the RS50’s extra 500 mAh per cell and 70 A rating is the point: cruise stays high without needing 2P for current.
P45B still makes sense if you already have a pack design around it, or you are chasing a specific high-drain 45 A build. It is not a higher-spec RS50. It is a different cell with less capacity and less continuous current.
Genuine vs relabeled
21700 FPV packs are full of rewraps. Hyperflux sells genuine RS50 cells and builds packs from the same stock — not a relabeled 30 A cell with a 70 A sticker. If you are rolling your own, buy cells you can trace.
See the RS50 cell spec table, or request a custom pack on these cells.