What's in This Bundle
- 2x Samsung INR18650-20R4, 2,000mAh (max), Flat Top
- 1x XTAR MC2 dual-slot USB-C charger
- 1x USB-C charging cable (included with the charger)
A ready-to-go starter kit for anyone who needs two matched, genuine high-drain 18650 cells and a compact way to charge them — no separate charger purchase, no guessing whether a charger you already own is a safe match for these cells.
This listing is for Flat Top. Looking for Button Top? Click here to buy: Samsung 20R4 Button Top + XTAR MC2 Bundle.
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 listed the numbers we have below and sourced them 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.
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. Flat Top is the standard terminal type for most current-generation devices — DIY packs, tool battery builds, and equipment that doesn't rely on spring-loaded contacts. Buying two cells together as a matched pair means you're starting with cells from a similar batch — which matters more for a high-drain cell like this one, since mismatched internal resistance between cells in a pack shows up faster under heavy load.
The XTAR MC2 pairs well here because it charges both slots at a full 1A simultaneously, with no current-splitting trade-off for using both bays at once — a comfortable, conservative rate relative to this cell's 4A max charge spec.
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 — generally a sign of more consistent manufacturing, though we'd rather show you the actual numbers than round them into "identical."
XTAR MC2 — Charger Specs
| Parameter |
Value |
| Input |
Type-C, 5V⎓2A |
| Charging Current |
1A per slot — both slots simultaneously, no splitting |
| Charging Method |
3-stage charging (trickle → constant current → constant voltage), 2 independent slots with automatic detection |
| End-of-Charge Voltage |
4.2V ±0.05V |
| End-of-Charge Current |
<130mA cutoff |
| Operating Temperature |
0°C to 40°C |
| Dimensions |
L103mm x W53mm x H30mm |
| Weight |
54g |
| Compatible Cell Sizes |
3.6V/3.7V Li-ion, sizes 10440 through 26650 (10440, 14500, 14650, 16340, 17335, 17500, 17670, 18350, 18490, 18500, 18650, 18700, 20700, 21700, 22650, 25500, 26650), including protected 21700 cells |
| Extra Feature |
"0V" activation technology — can recover some over-discharged cells |
| Status Indicators |
Green = standby/fully charged, Red = charging, Off/unlit = reverse polarity or abnormal insertion |
| Safety |
Reverse polarity protection, short-circuit protection, 3-stage charge control |
A realistic note on charge time: at 1A per slot against a 4A max charge rating, you've got real margin here — a full charge from empty takes roughly 2-2.5 hours, both cells at once.
This listing is for Flat Top. For Button Top, click here
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 — this matters more, not less, for a cell marketed on resistance consistency.
-
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.
-
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). We'd rather give you the real numbers than claim the two cells are identical.
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 — it's the standard for most current tool packs and DIY builds. If your device specifically calls for Button Top (a raised positive terminal), you'll want that version instead.
Can this charger handle this cell's full capacity safely? Yes. The MC2's 1A per slot is comfortably under this cell's 4A max charge rating — a full charge takes roughly 2-2.5 hours, both cells at once.
Can I charge two different battery sizes at once? Yes — the MC2's two slots operate independently with automatic size and chemistry detection, so you could charge one 18650 and a differently-sized cell (like a 21700) at the same time if needed.
Is this kit protected-cell compatible? The MC2 supports protected 21700 cells if you use it for those later. The cells included in this bundle are unprotected bare cells.
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 pair of Samsung INR18650-20R4 Flat Top cells with a verified XTAR MC2 charger — ready for power tool packs, e-bike builds, and other high-drain applications out of the box.
Authentic Samsung Cells – sourced from official distributors. No rewraps, no fakes.
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