What's in This Bundle
- 4x Samsung INR18650-20R4, 2,000mAh (max), Flat Top
- 1x XTAR MC4S 4-slot Type-C charger
- 1x USB-A to USB-C charging cable and user manual (included with the charger)
A complete kit for anyone running a 4-cell high-drain device — four matched cells paired with a compact, no-frills 4-bay charger that also handles Ni-MH/Ni-Cd batteries if you need that flexibility.
A note on "20R4": this is a distinct cell revision, not simply a batch label for the standard INR18650-20R. Based on the lab-test data available for this specific cell, it differs from the standard 20R in a couple of measurable ways — most notably a 20A max continuous discharge rating (versus 22A on the standard 20R) and a tighter internal resistance spec. We've sourced these numbers from supplier lab testing rather than a publicly available Samsung SDI datasheet, since we haven't located one specific to this revision. If you have a manufacturer spec sheet that differs from what's below, let us know before ordering.
This listing is for Flat Top. Looking for Button Top? Click here to buy: Samsung 20R4 Button Top + XTAR MC4S Bundle.
Why This Pairing Makes Sense
Like the standard 20R, this is a lower-capacity, high-current cell suited to power tool packs, e-bike builds, and other applications where sustained current draw matters more than runtime per cell. Buying four cells together as a matched set means consistent capacity and internal resistance across the group — this matters more, not less, for a high-drain cell, since mismatched cells show up faster under heavy load. Flat Top is the standard terminal type for most current devices — DIY packs, tool battery builds, and equipment that doesn't rely on spring-loaded contacts.
The XTAR MC4S is a straightforward 4-bay charger with a Type-C input (an upgrade over the older Micro-USB MC4), intelligent charging-strategy selection based on battery chemistry, and enough flexibility to also charge AA/AAA Ni-MH or Ni-Cd cells if you need a second use for it beyond 18650s.
Samsung INR18650-20R4 — Battery Specs
| Parameter |
Value |
| Brand & Model |
Samsung INR18650-20R4 |
| Max Capacity |
2,000mAh |
| Min Capacity |
1,900mAh |
| Rated Voltage |
3.6V |
| Max Charge |
4A / 4.2V |
| Max Discharge |
20A / 2.5V cutoff |
| Internal Resistance |
14mΩ ±3 (lab-tested) |
| Net Weight |
~44g |
| Cell Dimensions |
Height 65mm, Diameter 18mm |
| Terminal Type |
Flat Top |
| Protection Circuit |
None (unprotected cell) |
How this compares to the standard Samsung 20R: capacity is essentially the same (2,000mAh), and the max charge current matches (4A). The two measurable differences are discharge rating (20A here versus 22A on the standard 20R) and internal resistance, where this batch's lab-tested figure (14mΩ) runs lower than what's typically measured on standard 20R cells.
This listing is for Flat Top. For Button Top, click here
XTAR MC4S — Charger Specs
| Parameter |
Value |
| Input |
Type-C, DC 5V⎓2.1A |
| Charging Current |
1A×2 (CH1 & CH4) or 0.5A×4 (all slots occupied) |
| Charging Method |
TC-CC-CV 3-stage charging (trickle → constant current → constant voltage), automatic strategy selection by battery chemistry |
| Charge Cut-off Voltage |
4.20V ±0.05V |
| Charge Cut-off Current |
≤70mA |
| Operating Temperature |
0°C to 40°C |
| Dimensions |
L100mm x W97mm x H26.5mm |
| Net Weight |
95g |
| Compatible Cell Sizes |
3.6V/3.7V Li-ion/IMR/INR/ICR: 10440, 14500, 14650, 16340, 17500, 17670, 18350, 18490, 18500, 18650, 18700, 20700, 21700, 22650, 25500, 26650 (CH1 & CH4 support the full range including 26650; CH2 & CH3 support up to 21700 only). 1.2V Ni-MH/Ni-Cd: AAAA, AAA, AA, A, SC, C |
| Notes |
Can fit two 26650 cells (CH1 & CH4) plus two unprotected 21700 cells (CH2 & CH3) at once; cannot charge protected 20700/21700 cells |
| NiMH/NiCd Detection |
Precise full-charge detection via 0ΔV and -ΔV monitoring, high-precision MCU |
| Extra Feature |
0V activation — can recover some over-discharged cells |
| Status Indicators |
Red = charging/activating/slot short-circuit; Green = fully charged, no battery inserted, or poor contact; Blinking red+green = reverse polarity (reinsert cell correctly) |
| Safety |
Overcurrent, over-voltage, and short-circuit protection |
A realistic note on charge time: with all four bays occupied, the MC4S delivers 0.5A per slot — a full charge for all four 20R4 cells takes roughly 4.5-5 hours. If you only use the outer two slots (CH1 & CH4), you can get 1A per cell instead, cutting that time roughly in half.
Where This Cell Fits
-
Power tool battery packs — cordless drills, saws, and similar tools that draw hard and often
-
E-bike and e-scooter packs — commonly used in multi-cell parallel configurations
-
DIY packs prioritizing current over runtime, especially builds where consistent internal resistance across cells matters for pack balance
Not the right choice if you want strong runtime from a small number of cells, or if you need the slightly higher 22A ceiling of the standard 20R for a specific application.
Things Worth Knowing Before You Use This Kit
-
This is an unprotected cell. The charger enforces its own voltage and current cutoffs, but your device still needs to handle discharge-side protection.
-
Don't mix these with standard 20R cells or older 20R4 batches in the same pack. Even with similar specs, small differences in internal resistance or capacity between cells can cause imbalanced charging over time.
-
Flat Top won't work in devices that specifically require Button Top cells — check your device's battery compartment before ordering if you're not sure which terminal type it needs.
-
CH2 and CH3 don't support 22650/25500/26650 or protected 20700/21700 cells — for larger cell sizes, use the outer CH1/CH4 slots.
-
This is a lower-capacity cell by design, whether standard 20R or 20R4 — don't expect 25R or 30Q-level runtime from it.
Frequently Asked Questions
What's actually different between this and the standard Samsung 20R? Based on the lab data we have for this batch, capacity and max charge current are essentially the same. The measurable differences are a slightly lower max continuous discharge rating (20A vs. 22A) and a tighter, lower internal resistance spec (14mΩ vs. the standard 20R's typical range).
How is the MC4S different from the older MC4? Mainly the input connector — the MC4S uses Type-C instead of the older MC4's Micro-USB, plus a slightly tighter charge cutoff current (≤70mA vs. ≤120mA). Charging current profile and overall dimensions are essentially the same between the two.
Will Flat Top cells work in my device? If your device uses spring-loaded, flat, or magnetic-style contacts without a raised positive terminal requirement, Flat Top is the correct choice. If your device specifically calls for Button Top (a raised positive terminal), you'll want that version instead.
Does this charger work with rechargeable AA/AAA batteries too? Yes — the MC4S automatically detects Ni-MH/Ni-Cd chemistry and applies a dedicated charging strategy with precise full-charge detection, separate from its Li-ion charging profile.
Is this kit protected-cell compatible? No — the MC4S cannot charge protected 20700/21700 cells. The cells included in this bundle are unprotected bare cells, which is standard for this model and compatible with the charger.
What does the "0V activation" feature do? It lets the charger attempt a slow, controlled charge on cells drained deep enough that a standard charger would refuse to recognize them at all. It won't save every over-discharged cell, but it can recover some that would otherwise be written off.
In stock now. This bundle ships as a matched set of four Samsung INR18650-20R4 Flat Top cells with a genuine XTAR MC4S charger — a compact, Type-C-equipped way to charge a full set of high-drain cells.
