Why This Bundle
The Samsung 50S steps up from the 50E with the same 5000mAh capacity but a significantly higher discharge ceiling — 20A continuous without a temperature cutoff, or up to 35A with an 80°C thermal cutoff — making it a stronger choice for e-bikes, power tools, and drones that need both energy and real current delivery. Six of these cells need a charging setup that can keep up — at home and on the go. This bundle pairs 6 genuine Samsung INR21700-50S batteries with the NITECORE UMS4 (a 4-bay smart LCD charger for fast, monitored charging at your desk) and the NITECORE UI1 (an ultra-compact single-slot charger for travel or topping off a spare cell). Together, all 6 batteries can be charged at once — 4 in the UMS4, and the 5th and 6th staggered through the UI1 — with full visibility into every cell's health.
Samsung INR21700-50S Specifications
| Item |
Spec |
| Model |
Samsung INR21700-50S (Flat Top) |
| Nominal Capacity |
5000mAh |
| Minimum Capacity |
4900mAh |
| Nominal Voltage |
3.6V |
| Max Continuous Discharge |
20A (no temp cutoff) / 35A (80°C temp cutoff) |
| Standard Charge Current |
2.5A |
| Rapid Charge Current |
6A |
| Charge Cutoff Voltage |
4.20V |
| Discharge Cutoff Voltage |
2.5V |
| Chemistry |
Li-ion, high-capacity/high-discharge |
| Cell Size |
21700 (approx. Φ21.25mm × 70.6mm, max weight 72g) |
| Terminal Type |
Flat Top only |
| Protection Circuit |
None (unprotected cell) |
| Typical Use |
EVs, e-bikes, drones, power tools, e-mobility, and other high-capacity high-drain battery pack builds |
Note: Samsung's own product positioning lists the 50S for EV, e-bike, drone, power tool, and e-mobility applications, and explicitly states it is not intended for e-cigarettes, flashlights, RC cars, or electric skateboards.
This is an unprotected cell — avoid mixing with batteries of a different brand, model, or charge state, and inspect the wrap for damage before every use to prevent short circuits.
The Chargers: NITECORE UMS4 + NITECORE UI1
NITECORE UMS4 — 4-Bay Smart LCD Charger
-
USB-C input with QC support: up to 4,000mA total output, up to 3,000mA on a single bay with a QC adapter — the closest match here to the 50S's 2.5A standard charge current
-
Independent 4-bay control: charge and monitor each battery separately
-
Real-time LCD display: shows battery health (Good/Poor), internal resistance, charging current, voltage, charged capacity, and charging time
-
3 automatic charging modes: CC, CV, and -dV/dt, selected automatically based on battery type and charge level
-
Manual adjustment: set charging voltage and current (300mA–3000mA) for specialized battery types
-
Safety features: automatic internal resistance detection, reverse-polarity and short-circuit protection, overtime charging protection, and over-discharged battery activation/restoration
-
Fire-retardant PC/ABS housing with built-in temperature regulation
NITECORE UI1 — Compact Single-Slot Charger
-
Type-C input: automatically adapts to the optimal charging mode, works with power banks, solar panels, and USB adapters
-
Up to 1000mA output with automatic CC/CV mode selection
-
Trickle charging protects over-discharged cells and extends battery lifespan
-
Over-discharge activation for protected Li-ion batteries
-
Ultra-lightweight: just 40.5g — ideal for travel, a backup charge, or topping off the 6th cell while the UMS4 handles the other 4
Supported Battery Types & Voltage
NITECORE UMS4 — compatible with 3.6V/3.7V Li-ion, 3.8V Li-ion, 3.2V LiFePO4, and 1.2V Ni-MH/Ni-Cd batteries, including the Samsung 50S (21700) in this bundle: IMR/Li-ion/LiFePO4: 10440, 14500, 14650, 16500, 16340(RCR123), 16650, 17350, 17500, 17650, 17670, 17700, 18350, 18490, 18500, 18650, 18700, 20700, 21700, 22500, 22650, 25500, 26500, 26650, 26700 Ni-MH/Ni-Cd: AA, AAA, AAAA, C, D Output: up to 3,000mA per bay (QC mode) / 4,000mA total
NITECORE UI1 — compatible with 3.6V/3.7V Li-ion/IMR batteries, including the Samsung 50S (21700): 10340, 10350, 10440, 10500, 12340, 12500, 12650, 13450, 13500, 13650, 14430, 14500, 14650, 16500, 16340(RCR123), 16650, 17350, 17500, 17650, 17670, 18350, 18490, 18500, 18650, 20700, 21700, 22500, 22650, 25500, 26500, 26650 Output voltage: 4.2V±1% · Output current: up to 1000mA
Compatibility Notes
The UMS4's bays and spring-loaded contacts are sized to accommodate 21700 cells like the 50S without any adapter, and the UI1's slot fits the same length range. Since the 50S has a relatively large 5000mAh capacity, charging speed does matter here: the UMS4 (up to 3,000mA on a single occupied bay) will get closer to the 50S's 2.5A rated charge current than the UI1 (up to 1,000mA), so we'd suggest running your most time-sensitive cells through the UMS4 and using the UI1 for the batteries you're least in a hurry about.
What's Included
- Samsung INR21700-50S Battery × 6
- NITECORE UMS4 4-Bay Charger × 1
- NITECORE UI1 Single-Slot Charger × 1
- USB-C Charging Cables × 2
- User Manuals × 2
Safety Tips
- Store batteries in a proper case, keeping them away from loose metal objects to prevent short circuits
- Never disassemble, puncture, burn, or submerge the batteries
- Charge only with genuine, compatible chargers such as the NITECORE UMS4 and UI1
- The 50S is an unprotected cell intended for compatible, purpose-built devices such as EVs, e-bikes, drones, and power tools — it is not intended for e-cigarettes, flashlights, RC cars, or electric skateboards
- Never discharge below 2.5V or charge above 4.2V
FAQ
Q: Can I charge all 6 batteries at the same time? A: Yes. The UMS4 charges 4 batteries independently and simultaneously, while the UI1 can charge a 5th battery alongside it — or you can stagger the 5th and 6th through the UI1 if only one is used at a time.
Q: Is the Samsung 50S suitable for flashlights? A: No. Samsung's own product positioning explicitly states this cell is not intended for lashlights, RC cars, or electric skateboards. It's built for EVs, e-bikes, drones, power tools, and e-mobility applications.
Q: How does the 50S compare to the 50E? A: Both share the same 5000mAh capacity, but the 50S has a meaningfully higher discharge ceiling — 20A continuous (35A with thermal cutoff) versus the 50E's 9.8A — making the 50S the better pick for applications that need more current alongside the capacity.
Q: Will 21700 batteries fit in both chargers? A: Yes. Both the UMS4 and UI1 are sized to accommodate 21700 cells like the 50S without any adapter.
Q: What's the difference between the UMS4 and UI1 in this bundle? A: The UMS4 is a 4-bay charger with an LCD screen showing detailed real-time data (battery health, internal resistance, voltage, capacity) and faster QC charging up to 3,000mA on a single bay. The UI1 is a single-slot, ultra-compact charger (40.5g) best suited for travel or a slower backup charge — with a 5000mAh cell like the 50S, it will take noticeably longer to fill on the UI1 than on the UMS4.
Q: How do I check if a battery is degraded? A: The UMS4's LCD display shows battery health as "Good" or "Poor" along with internal resistance readings, making it easy to spot cells that have aged or lost performance.
Q: What's in the box? A: 6 Samsung INR21700-50S batteries, 1 NITECORE UMS4 charger, 1 NITECORE UI1 charger, 2 USB-C charging cables, and user manuals for both chargers.
