Hyperflux packs are genuine Reliance RS50 21700 cells in series (and parallel on 2P). Charge them on a Li-Ion / LiPo balance charger that can hit 4.20 V per cell and read the JST-XH balance tap. Never leave a pack charging unattended.
Charge rates
| Pack | Recommended charge | Notes |
|---|---|---|
| 1P (2S1P, 4S1P, 6S1P) | 1C — 5 A | Datasheet standard charge is 0.5C (2.5 A) per cell. 1C is fine for everyday use. |
| 2P (2S2P, 4S2P) | 1C — 10 A | Two cells in parallel share current. 10 A is 5 A per parallel group. |
| Loose RS50 cell | 0.5C — 2.5 A standard | Rate charge up to 8 A on a proper 21700 fixture. Do not clip-lead a high-rate charge. |
Charge voltage is 4.20 V/cell. End-of-charge is the charger’s taper, not a hotter voltage. More than 4.20 V does not give you extra flight time; it shortens the cell.
Cutoff and landing voltage
RS50 discharge cutoff is 2.5 V per cell — 5.0 V (2S), 10.0 V (4S), 15.0 V (6S). Treat that as a floor, not a target. Landing around 3.3–3.5 V/cell keeps cycle life closer to the datasheet’s 500 cycles to 80% capacity.
Storage
- For more than a few days, store at about 3.8 V per cell (storage charge on most chargers).
- Cool, dry, in a fireproof bag or box. Not in a hot car.
- Do not charge below 0 °C. Below ~15 °C the pack will feel soft until it warms.
- Never charge a swollen, punctured, or hot pack. Recycle damaged packs — not household waste.
Connector on Black Series packs is XT60; balance is JST-XH. Specs for each pack, including charge rate and cutoff, are on the product page — start with the 4S or 6S. Loose cells and the HTML spec table live on the RS50 cell page.