Samsung INR21700-40T – The perfect all-rounder (4000 mAh)
Product information
The Samsung INR21700-40T (short "Samsung 40T") is perhaps the most versatile battery in the modern 21700 format. It solves the problem that users often have: The decision between maximum runtime or maximum performance. With 4000 mAh it offers an enormous capacity (33% more than a 30T), but still delivers impressive 35 amps (with temperature monitoring) or a stable 25 amps in continuous operation without cooling. This makes it the "egg-laying wool-milk sow" for almost all high-performance applications.
Highlights at a glance
- The "sweet spot" of battery technology: The 40T combines the power of a high-current cell with the endurance of a high-capacity cell. It is the ideal compromise for users who do not need extreme competitive performance (as with the 30T) but want to work significantly longer.
- High capacity (4000 mAh): Offers significantly more energy reserve than classic 18650s (usually max. 3000 mAh at high current) or the Samsung 30T. This means longer evenings with the torch or more puffs on the e-cigarette before charging is required.
- Powerful power output: Even if it doesn't quite come close to the 30T, the 25-35 amps more than enough for 95% of all applications, including powerful e-bikes, hoovers and torches in turbo mode.
- Future-proof format: The 21700 format (21mm diameter, 70mm length) physically offers more volume for the chemistry than 18650s, which makes these performance data possible in the first place.
- Market-leading quality: Samsung SDI cells are known for their consistency. If you buy 10, all 10 will behave almost identically – important for battery packs.
40T vs. 30T vs. 50E/50S
To categorise the 40T, a comparison with its "siblings" helps:
- Samsung 50E (5000 mAh): Maximum runtime, but weak on the chest (only 10A). Suitable for e-bike "cruising" or normal lamps.
- Samsung 30T (3000 mAh): Maximum power (35A+), but battery drains quickly. Only for extreme peak loads.
- Samsung 40T (4000 mAh): The golden mean. Lots of power AND lots of runtime. It is therefore usually the best choice for everyday use.
Features
| Model | Samsung INR21700-40T (Often referred to as 40T3) |
| Application | Powerful torches, e-mobility (skateboards), professional tools |
| Nominal capacity | 4000 mAh (The perfect compromise) |
| Rated voltage | 3.6 V |
| End-of-charge voltage | 4.2 V (standard CC/CV charge) |
| Max. Discharge current | **30 A** (continuous load) / **35 A** (temperature monitored < 80°C) / 45A (peak) |
| Internal resistance | Very low (approx. 12 mOhm AC) - Low waste heat |
| Protective circuit (PCB) | No (Unprotected / Flat Top) - Caution during transport! |
| Chemistry | NMC (Nickel Manganese Cobalt) |
| Dimensions (Ø x L in mm) | 21.1 x 70.3 (Does not fit into 18650 slots!) |
| Weight (g) | approx. 70 |
FAQs about the Samsung 40T
Will the battery fit in my device, which previously had 20700 batteries?
Yes in 99% of cases. 20700 and 21700 are almost the same length (70mm). The 21700 is only 1 millimetre thicker. Most battery compartments have enough clearance ("rattle") so that the 40T fits and is an excellent upgrade.
Is it suitable for e-cigarettes?
Yes, excellent. It is the standard for regulated 21700 battery carriers. You can easily vape up to 70-80 watts per cell and still have a very good runtime. Only for extremely low-resistance mechanical mods (under 0.12 Ohm) do professionals tend to use the 30T.
Can I use it as a replacement for 18650?
Only if the device is compatible. The 40T is thicker and longer. It does not fit into a pure 18650 tube. However, some devices are supplied with adapters and can take both sizes. Check the instructions.
What does "T3" or "T4" mean on the battery?
These are internal revisions (40T3, 40T4). This makes little difference to the end user as the performance data is almost identical.
| Capacity: | 4Ah |
|---|---|
| Tension: | 3,6V |
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