Ember 21700 Battery 4000mAh
A 4000 mAh 21700 cell for box mods that take the larger battery format.
- 21700 format, 4000 mAh
- Higher capacity than 18650
- For mods that accept 21700
- Charge externally for best life
SKU: ET-EMBER21700BATT-01
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- Prices in AEDVAT included
Description
21700 versus 18650
A 21700 is physically larger than an 18650 and carries roughly a third more capacity. If your mod accepts both — many do, with an adapter sleeve for the smaller cell — the 21700 is the obvious choice for longer runtime at the same wattage.
Check compatibility first
Not every mod takes 21700 cells. Measure or check the manual before ordering: a 21700 will not fit an 18650-only bay, and forcing it risks damaging the contacts.
Safety, which matters more than capacity
Inspect the wrap before each use; a torn wrap on a bare cell is a short circuit waiting to happen. Never carry cells loose in a pocket with keys or coins. Replace any cell that gets hot, dents, or holds noticeably less charge than it did.
Charging
An external charger such as the Ember Quad Battery Charger treats cells more gently than charging in the mod, and lets you inspect each one as you go. In dual-battery mods, always use a matched pair.
Amp rating
Check the continuous discharge rating in the specifications above against the wattage you intend to run.
Frequently asked questions
Will this fit my mod?
Only if it accepts 21700 cells. Check the manual — 21700 will not fit an 18650-only battery bay.
How much longer does it last than an 18650?
Roughly a third more capacity at 4000 mAh, so noticeably longer between charges at the same wattage.
Can I charge it in the mod?
Usually yes, but an external charger is gentler on the cell and lets you check the wrap each time.
Do I need two?
Only if your mod is dual-battery — and then always a matched pair, charged and replaced together.
When should I replace it?
If the wrap is torn, the cell dents or gets hot, or the runtime drops noticeably.