Hyperflux packs are genuine Reliance RS50 21700 cells in series (and parallel on 2P). Charge them on a HOTA, ISDT, or similar balance charger in Li-Ion mode, never LiPo mode. The charger must hit 4.20 V per cell and read the JST-XH balance tap. Plug that balance lead in on every charge. These packs have no BMS. Nothing on the pack stops a low cell, a short, or an over-charge. The charger and your flight cutoff do that work. Never leave a pack charging unattended. Charge on a hard, non-combustible surface, in a fireproof bag, while you are awake and present.
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 around 3.6–3.7 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. Do not put them in household waste.
- Do not charge or fly a pack that has crashed, swollen, been punctured, or got wet. A crash can start a fire later.
- If a pack hisses, heats up, or smells sweet, leave it where it is, get people out, and call 111 if it is burning.
- Loose RS50 cells short if the ends touch keys, coins, or each other. Do not carry them loose. Do not solder a cell. Use a spot welder and a holder.
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 2S 5000mAh Li-Ion pack, the 4S, or the 6S. Loose cells and the HTML spec table live on the RS50 cell page. Safety, shipping, and returns sit on Support.