What's in This Bundle
- 4x LG INR18650-MJ1, 3,500mAh, Flat Top
- 1x XTAR VC4SL 4-slot LCD USB-C charger
- 1x Type-C QC3.0 fast-charge cable, storage pouch, and manual (included with the charger)
A complete kit for anyone running a 4-cell device or building a small pack — four matched, genuine high-capacity cells paired with a charger that does more than just charge: it tests, monitors, and reports on each cell individually.
Flat Top is the MJ1's native factory configuration — this is the standard, unprotected form LG Chem manufactures the cell in.
This listing is for Flat Top. Looking for Button Top? Click here to buy: LG INR18650-MJ1 Button Top + XTAR VC4SL 4 Bundle.
Why This Pairing Makes Sense
The MJ1 was, at release, one of the highest-capacity 18650 cells on the market — LG's NMC811 chemistry with a silicon-graphite anode pushes energy density further than most cells in this size while still holding a genuine 10A continuous discharge rating. Four cells bought together as a matched set means consistent capacity and internal resistance across the group — which matters more than usual here, since independent testing has shown some batch-to-batch capacity variability with this cell. Flat Top is the standard terminal type for most current devices — DIY packs, work lights, and equipment that doesn't rely on spring-loaded contacts.
The XTAR VC4SL is a real step up from a basic charger: an LCD display showing live capacity, current, and internal resistance per slot, plus a capacity-test (grading) mode that charges, discharges, and recharges a cell to verify its actual capacity rather than just trusting the label. Given the batch variability noted below, this cell is a genuinely good candidate for that verification — you can confirm all four cells are performing consistently before you commit them to a build.
LG INR18650-MJ1 — Battery Specs
| Parameter |
Value |
| Brand & Model |
LG Chem INR18650-MJ1 |
| Chemistry |
NMC811 cathode, graphite-silicon anode |
| Capacity |
3,500mAh nominal (3,350mAh minimum) |
| Nominal Voltage |
3.635V average |
| Standard Charge |
0.5C (1.675A) CC, 4.2V CV, 50mA cutoff |
| Max Charge Voltage |
4.2V ±0.05V |
| Max Charge Current |
1.0C (~3.35A) |
| Standard Discharge |
0.2C (670mA), 2.5V cutoff |
| Max Continuous Discharge |
10A |
| Cycle Life |
400 cycles (charge 1.5A / discharge 4A) to 80% capacity |
| Charge Temperature |
0°C to 45°C |
| Terminal Type |
Flat Top (native factory configuration) |
| Protection Circuit |
None (unprotected cell) |
| Weight |
~49g max |
| Cell Dimensions |
Diameter 18.4mm (max 18.5mm), Height 65.0mm (max 65.2mm) |
A note on real-world capacity: independent lab testing has shown this cell's actual measured capacity can run somewhat below its 3,500mAh nominal rating in some batches — one third-party comparison test measured roughly 3,205-3,384mAh depending on discharge rate, noticeably below the datasheet figure. This isn't unique to the MJ1, but it's a genuine reason to prioritize matched-batch, verified sets like this bundle over mixing cells from different orders.
This listing is for Flat Top. For Button Top, click here
XTAR VC4SL — Charger Specs
| Parameter |
Value |
| Input |
Type-C, QC3.0 (9V⎓2A) |
| Charging Current (CC) |
3A×1 / 2A×2 / 1A×4 / 0.5A×4 / 0.25A×4 — steps down automatically as more slots are occupied, or can be manually adjusted within what the slot count allows |
| Charging Method |
3-stage charging (trickle → constant current → constant voltage), 4 independently monitored slots, dynamic power allocation based on input power available |
| Cut-off Voltage |
4.2V ±0.05V (Li-ion) / 1.45V ±0.1V (Ni-MH/Ni-Cd) |
| Cut-off Current |
≤120mA |
| Operating Temperature |
0°C to 40°C |
| Dimensions |
L156mm x W115mm x H35mm |
| Net Weight |
212g |
| Display |
Color LCD — press Mode to cycle between capacity, current, and internal resistance readouts per slot in real time |
| Special Modes |
Capacity/grading mode (charge → discharge → recharge cycle to verify true capacity), storage mode (charges or discharges cells to their rated storage voltage to extend battery life), standard charge mode |
| Compatible Cell Sizes |
3.6V/3.7V Li-ion: 10440, 14500, 14650, 16340, 17335, 17500, 17670, 18350, 18490, 18500, 18650, 18700, 20700, 21700, 22650, 25500, 26650, flat-top 32650. 1.2V Ni-MH/Ni-Cd: AAA, AA, A, SC, C. Supports protected 20700/21700 cells; spring-loaded slots can also fit two 32650s and two 18650s at once |
| Safety |
Reverse polarity protection (displays "Err," shows 0V, and stops automatically), auto cut-off when fully charged, multiple charge protections |
A realistic note on charge time: the MJ1's own standard charge current is 1.675A, meaningfully above the VC4SL's 1A-per-slot rate with all four bays occupied — expect a full charge in roughly 4.5-5 hours for all four cells at once, a conservative and safe rate relative to the cell's spec.
Why the Capacity Test Mode Matters for a 4-Pack
This is one of the clearest cases in our lineup for why grading mode earns its keep. Independent testing has already shown this cell can land meaningfully under its nominal rating depending on batch — buying four cells and being able to verify their actual measured capacity, rather than just trusting the 3,500mAh figure, tells you what you actually have before you build a pack around it. Cells with a wider gap during testing are worth flagging rather than mixing into a tight pack build.
Where the MJ1 Actually Fits
-
High-capacity flashlights and headlamps running moderate-to-high output modes
-
E-bike and e-scooter packs where 10A per cell in parallel is sufficient
-
4S, 2S2P, or similar DIY pack configurations prioritizing energy density with more current headroom than pure energy cells
-
DIY power banks and backup builds wanting more runtime per cell than lower-capacity options, built from a verified matched set
Not the right choice for sub-ohm mechanical mods, or anything regularly demanding more than 10A per cell — for those, a dedicated high-drain cell like the Samsung 25R or 30Q is a better match.
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 cells with older ones you already own, even if they're also MJ1. Given the batch-to-batch capacity variability noted in independent testing, running the grading test before combining batches is genuinely worthwhile.
-
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.
-
10A is a real ceiling. Don't use these in devices that regularly demand more current than that.
Frequently Asked Questions
Can this charger really tell me if a cell is underperforming? Yes — the grading/capacity test mode charges, discharges, and recharges a cell while measuring the actual capacity delivered, rather than relying on the printed rating. Given the batch variability documented for this cell, that's a genuinely useful check.
Why might my actual measured capacity come in under 3,500mAh? Independent testing has shown some batch-to-batch variation with this cell, with measured capacity sometimes landing in the 3,200-3,400mAh range depending on discharge rate and batch. It's still a genuine high-capacity cell — just worth knowing that the nominal figure is a typical rating, not a guarantee for every individual unit.
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 — and it's how LG manufactures this cell natively. If your device specifically calls for Button Top (a raised positive terminal), you'll want that version instead.
Do I need to charge all four cells at once? No — each of the four slots operates independently, so you can charge one, two, three, or four cells at a time, and mix different cell sizes or even NiMH batteries across the slots if needed.
What happens if I insert a cell backwards? The display shows "Err" for that slot and the voltage reading drops to 0 — the charger stops working on that slot automatically rather than attempting to charge.
In stock now. This bundle ships as a matched set of four genuine LG INR18650-MJ1 Flat Top cells with a verified XTAR VC4SL charger — ready for high-capacity flashlights, e-bikes, and general electronics out of the box.
