400mAh Battery – What is it in Vaping?

Definition

A 400mAh battery is a compact lithium-ion power cell rated to deliver 400 milliamp-hours of energy. In vaping, it sits inside small pod systems and entry-level vape pens, providing the electricity needed to heat a coil and turn 0mg nicotine or nic-salt e-liquid into vapour. Its main purpose is portability: the modest capacity keeps the device ultra-light while still offering most users a few hours of moderate vaping between charges.

Technical Details

Lithium cobalt or LiPo chemistry stores 3.2-4.2 V under load. A 400 mAh cell typically measures 30–40 mm long and 8–11 mm thick, making it perfect for slim 510-thread pods. Continuous discharge rating (CDR) ranges 5-10 A, enough for 8-15 W mouth-to-lung (MTL) coils but insufficient for high-wattage sub-ohm vaping. Variants include:

  • Integrated 400 mAh packs sealed inside the device (no user replacement)
  • Proprietary magnetic pods that snap in like cartridges
  • Micro-USB or USB-C charging at 0.5-1 A, reaching full charge in 45-70 min

Compared with larger removable cells such as the 18650 battery, 21700 battery or 26650 battery, the 400 mAh cell trades runtime for pocket-friendly size.

Usage & Tips

  • Maximise life: Avoid chain-vaping above 80 % of the CDR; allow 10-15 seconds between puffs to let the cell cool.
  • Re-charge early: Top up when the LED drops to 20 %, not zero, to reduce stress on the tiny LiPo.
  • Common problem: Sudden weak hits often mean pocket lint in the USB port—blow or gently scrape it clean.
  • Safety: Never leave a 400 mAh device charging overnight; small cells heat up faster and lack the thermal mass of larger 18650 or 21700 cells.

History & Context

400 mAh cells became popular around 2017 when JUUL and other ultra-portables replaced bulky box mods. Australian vapers now favour them for discreet MTL vaping in smoke-free zones, even as high-capacity 21700 and 26650 devices remain the choice for cloud-chasing at home.

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