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Tested & Certified
IEC 62133-2 UN 38.3 FCC CE RoHS
Li-ion 3.6V Li-ion 21700 Protected button-top
SCIGOLD 21700 Li-ion Cells — Standard
SCIGOLD 21700 lithium-ion rechargeable cells in 4,000 / 4,500 / 5,000 mAh capacities. 3.6V nominal, protected button-top, ≥280 Wh/kg energy density. The modern standard for e-bikes, scooters, high-output flashlights, and DIY power packs.
18,000
mWh max
500+
Charge cycles
15 A
Max discharge
280
Wh/kg density
- Cell size
- 21700
- Power
- 3.6V Li-ion
- Material
- Protected button-top
- SKU range
- SL2170040 / SL2170045 / SL2170050 — 3 capacities × 2 packs = 6 SKUs
Capacity 4000mAh
Pack 2-pack
Price SG-2170-40-2
$14.99 USD · in stock
Specs at a Glance
Everything in the spec sheet.
- 3 capacity options: 4,000 / 4,500 / 5,000 mAh (14,400 ~ 18,000 mWh)
- Nominal voltage 3.6V — same as 18650 (drop-in for any 3.6V circuit)
- 20% larger volume than 18650 / 40% more energy per cell
- Standard discharge current: 12A — 15A depending on capacity
- Protected button-top safety circuit (overcharge / over-discharge / short)
- Energy density ≥280 Wh/kg — class-leading
- Operating temperature: -20°C ~ 55°C
- Internal resistance ≤22mΩ (≤25mΩ on 5,000 mAh)
- 500+ cycles to 80% capacity retention (IEC 61960-3)
- Dimensions: 21.9 × 71.0 mm · 66~69±2g per cell
The 21700 cell that’s quietly replacing 18650 everywhere.
In 2017 Tesla switched the Model 3 from 18650 to 21700. By 2021, every major EV and most premium e-bike OEMs followed. The math is simple: same form-factor philosophy, 20% larger volume, 40% more energy. SCIGOLD’s 21700 brings consumer access to the cell that’s already inside the cars and bikes you ride.
Pick your capacity
| Capacity | Energy | Max current | Best for |
|---|---|---|---|
| 4,000 mAh (14,400 mWh) | 12A | Entry e-bike DIY, modern tactical flashlights | |
| 4,500 mAh (16,200 mWh) | 13.5A | Balanced — most popular for DIY power packs | |
| 5,000 mAh (18,000 mWh) | 15A | Long-runtime needs, e-scooter packs, expedition gear |
All three share 21.9 × 71.0 mm dimensions. The 5,000 mAh has a slightly more conservative voltage profile (charge cut-off 4.2V vs 4.25V) for extended cycle life.
Where 21700 makes sense (and where 18650 still wins)
Pick 21700 if:
- Building / rebuilding an e-bike or e-scooter pack (BMS designed for 21700 since ~2021)
- High-end tactical flashlights (Olight Marauder 2, Acebeam X75, Fenix LR50R)
- DIY power banks / battery packs where space allows
- You want maximum energy density per slot
Stick with 18650 if:
- Replacing cells in an existing 18650 device (flashlight, vape mod, power tool pack)
- Battery holder is 18650-specific (21700 won’t physically fit)
- Cost-conscious — 18650 is still cheaper per mWh
Compared to 18650
| 21700 | 18650 | |
|---|---|---|
| Capacity range | 4,000-5,000 mAh | 2,000-2,500 mAh (Standard) / 3,500-4,000 mAh (Cold-Weather) |
| Energy density | ≥280 Wh/kg | ≥260 Wh/kg |
| Volume | 21.9 × 71 mm | 18.5 × 65.3 mm |
| Weight | 66-69 g | 44 g |
| Discharge current | 12-15A | 6-7.5A (Standard) |
| Use in modern devices | Tesla, e-bikes, premium flashlights post-2021 | Universal — legacy + current devices |
| Price per mWh | ~$0.00094 | ~$0.00125 |
21700 is 30% cheaper per mWh but 50% heavier per cell — pick by whether you’re optimizing for cost-per-energy or compactness.
Compatible with our CW401 charger
The CW401 18650/21700/Li-ion smart charger takes both sizes automatically (4 slots, LCD per slot, auto-detect 3.6V Li-ion). One charger, both cells, no hardware swap.
Frequently Asked
Quick answers, before you buy.
How much more energy does a 21700 hold than an 18650?
A 21700 cell holds roughly 40% more energy than an 18650 while occupying about 20% more volume. SCIGOLD 21700 cells reach 4,000 to 5,000 mAh, equal to 14,400 to 18,000 mWh at 3.6V nominal, compared with 2,000 to 2,500 mAh for the 18650 Standard. That is why modern EVs and e-bikes migrated to the larger format.
What capacities do SCIGOLD 21700 cells come in?
Three capacities are offered: 4,000 mAh, 4,500 mAh, and 5,000 mAh, delivering about 14,400, 16,200, and 18,000 mWh per cell. All share 21.9 by 71.0 mm dimensions. The 4,500 mAh is the most popular balance for DIY packs, while the 5,000 mAh uses a slightly more conservative charge profile for extended cycle life.
Can I use SCIGOLD 21700 cells in an e-bike or scooter?
Yes. The 21700 is the modern standard for e-bike and e-scooter packs, and most BMS hardware has been designed around it since around 2021. With a class-leading energy density of at least 280 Wh/kg and 12A to 15A discharge current, these cells suit both factory pack rebuilds and DIY high-output battery builds.
Are SCIGOLD 21700 cells protected button-top?
Yes. Every 21700 Standard cell is a protected button-top with an integrated safety circuit covering overcharge, over-discharge, and short-circuit protection. The raised terminal ensures reliable contact in flashlights and holders. As with any button-top, allow a little extra length when fitting tightly spaced battery slots.
Is a 21700 cell a drop-in replacement for an 18650?
Electrically yes, since both run at 3.6V nominal, so a 21700 works in any 3.6V Li-ion circuit. Physically no, because at 21.9 by 71.0 mm the 21700 will not fit an 18650-specific holder. Use 21700 when your device or pack is sized for it; otherwise choose our 18650 Standard cells instead.
What devices use 21700 cells?
The 21700 powers e-bikes, e-scooters, and high-output tactical flashlights such as the Olight Marauder 2, Acebeam X75, and Fenix LR50R, plus DIY power banks and battery packs where space allows. It has been the dominant cell in premium post-2021 devices that prioritize maximum runtime per slot.
From the Lab
