Vaporizer Battery: How to Charge and Care for 18650, 21700 and 26650 Cells

A vaporizer battery labelled 18650, 21700 or 26650 is a cylindrical lithium-ion cell: the first two digits stand for the diameter, the following ones for the length in millimetres. Which cell your device needs is specified by the manufacturer. Charge it in the device or in a suitable charger, store it partially charged and take old batteries to a collection point.

What do 18650, 21700 and 26650 mean?

The number describes the cell's form factor: diameter and length in millimetres, with the final digit 0 standing for the round, cylindrical shape. The number alone says nothing about capacity, current rating or quality.

A look at cell manufacturers' data sheets shows how closely the dimensions match the designation:

Form factor Diameter (approx.) Length (approx.) Example according to data sheet
18650 18 mm 65 mm Panasonic UR-18650AA: max. 18.5 mm × 65.1 mm (with sleeve)
21700 21 mm 70 mm Molicel INR-21700-P50B: max. 21.55 mm × 70.15 mm
26650 26 mm 65 mm Voltcraft 26650 cell: 26.5 mm × 65.5 mm

Important for you: the same form factor does not automatically mean the same cell. Two 18650 batteries can differ in capacity, current rating, terminal design and protection circuit. That is why the manufacturer's specification for your device always has the final say.

Which battery does my vaporizer need?

The right battery is stated by your vaporizer's manufacturer on the product page or in the user manual. The following overview summarises the manufacturers' specifications for some devices.

Device Battery according to the manufacturer Replaceable Charging according to the manufacturer
Arizer Air SE 18650 lithium-ion Yes Micro-USB in the device, full charge approx. 3.5 hours; external 18650 dual charger available
Arizer ArGo (Arizer Go) 18650 (Arizer replacement battery compatible with Go, Air SE and Air II) Yes In the device or in Arizer's 18650 dual charger
Arizer Air MAX 26650 lithium-ion Yes USB-C in the device, up to 90 % in approx. two hours; external 26650 charger available
Arizer Solo II MAX Dual-cell 18650 No, not user-replaceable USB-C, 5 V / 3 A charger, full charge approx. 3 hours
Limelight Frolic 21700, 5000 mAh Yes USB-C in the device (5 V / 2 A) or externally
Smono Lunari 18650, 3200 mAh Yes USB-C
Smono Balu 18650 Yes USB-C

You can find the devices here: Arizer Air SE, Arizer Air MAX, Arizer Solo II MAX, Limelight Frolic, Smono Lunari and Smono Balu. The manufacturer has archived the Arizer ArGo; it is no longer available from us.

According to Arizer, the usage time per charge depends on the set temperature and usage. As guide values, Arizer states up to 80 minutes for the Air SE, up to 2¼ hours for the Air MAX and up to 3 hours for the Solo II MAX.

Can I use any 18650 battery?

No, not without further ado. Arizer explicitly stipulates using only official Arizer batteries and chargers and avoiding third-party products, counterfeits or unknown brands.

The reason: the form factor alone does not guarantee that the cell matches the electronics and heating element of your device. Current rating, capacity and terminal design differ from cell to cell. The German Environment Agency (Umweltbundesamt) also recommends using only chargers and charging cables intended for the battery or device. For the Smono Balu and Smono Lunari, matching replacement cells are available from the manufacturer. For other devices: use the battery type and model from the manual and, if in doubt, ask the manufacturer.

How do I replace a vaporizer battery correctly?

Only replace the battery with the device switched off and make sure the polarity is correct when inserting it. Arizer and Smono both point out that the positive and negative terminals must be aligned correctly.

  1. Switch off the vaporizer and let it cool down.
  2. Open the battery compartment as described in the manual, on the Air SE for example by sliding down the rear cover.
  3. Remove the empty battery and check the new battery for damage to the sleeve, dents or signs of leakage.
  4. Insert the new battery so that plus (+) and minus (−) match the marking in the device.
  5. Keep the contacts clean and dry, as Smono recommends.
  6. Close the battery compartment and check the battery indicator when switching on.

According to Arizer, the battery in the Solo II MAX and the Solo III v2.0 is not user-replaceable. Do not open these devices yourself.

How do I charge a vaporizer battery: in the device or externally?

Both are possible if the manufacturer provides for it. In the device you charge via the supplied cable, externally with a charger that the manufacturer offers for this cell.

  • Charging in the device: the battery stays in place and you use the USB port. For the Air SE, Air MAX and Solo II MAX, Arizer states that the device can also be used while charging, but charging then takes longer.
  • External charger: practical if you work with replaceable batteries. While one cell is in the device, the second one charges. For 18650 batteries, Arizer offers a dual charger, available here as the Arizer Air II / ArGo dual battery charger. For the Air MAX's 26650 battery there is the Arizer Air MAX battery charger.
  • Limelight Frolic: according to Limelight, the 21700 cell can be charged either externally or via the USB-C port at 2 A.

The following also applies to Arizer devices: according to the manufacturer, an Air SE does not work when the battery is completely empty. After 15 to 20 minutes of charging, you can use it again. You can find more chargers and spare parts under Accessories & Spare Parts.

What safety rules apply to lithium-ion batteries?

Lithium-ion batteries are safe if you use them as intended. However, Arizer clearly warns: lithium batteries can explode or cause a fire if they are used incorrectly or are defective.

The German Environment Agency recommends the following when charging:

  • Only use the charger and charging cable intended for the battery or device.
  • If possible, charge in a place with a smoke detector, with no flammable materials in the immediate vicinity.
  • Stay nearby and do not charge overnight or while asleep.
  • Disconnect the charger from the mains after charging.
  • Do not expose the battery to high heat or water, as the consumer advice centre Verbraucherzentrale NRW also stresses.

Arizer adds: do not drop the battery or the device. If a battery has been dropped or damaged, keep it in a safe, dry place for at least one hour and then check whether it has become hot.

What should I do if the battery sleeve (wrapper) is damaged?

Stop using the battery. Smono explicitly advises against using cells with a damaged sleeve, dents or signs of leakage.

The plastic sleeve, often called a wrapper, insulates the cell. If it is torn or worn, the risk of a short circuit increases. For damaged, deformed, swollen or leaking batteries, the German Environment Agency advises:

  1. Do not continue to use the battery and do not open it.
  2. Remove the battery from the device immediately; if electrolyte has leaked, only with protective gloves.
  3. Tape over the terminals and transport the battery in a sealable container, such as a screw-top jar, filled with sand if possible.
  4. Take the battery to a collection point and tell the staff that it is damaged.

How do I store spare batteries correctly?

Store spare batteries partially charged, cool, dry and separate from metal objects. Arizer recommends not storing batteries fully charged or fully discharged for longer than one month.

  • State of charge: for longer storage, the German Environment Agency states around 40 to 50 %. For the Solo III v2.0, Arizer recommends 50 % for long storage periods.
  • Temperature: according to the German Environment Agency, 10 to 25 °C is ideal. Do not store them in the car behind the windscreen, outdoors, in damp rooms or in the fridge.
  • Protection against short circuits: Arizer recommends a separate plastic case for each battery, away from metal. Smono recommends keeping spare cells separate from coins and keys. For this purpose, Arizer offers a battery box for two 18650 cells.

How do I dispose of an old vaporizer battery in Germany?

Old batteries never belong in household waste. You can drop them off free of charge at a collection box in a shop or at a municipal collection point such as a recycling centre.

Since 7 October 2025, the Battery Law Implementation Act (Batterierecht-Durchführungsgesetz, BattDG) has applied in Germany. According to the German Environment Agency, it replaces the previous Battery Act and implements the EU Battery Regulation. For you, nothing changes:

  • Retailers that sell batteries must take back waste batteries of the types they stock free of charge, even without a new purchase.
  • You can recognise take-back points by the “Batterierücknahme” (battery take-back) logo.
  • Tape over the terminals before storage and disposal to prevent a short circuit.
  • For devices with a permanently installed battery, such as the Solo II MAX, hand in the entire device at a collection point for waste electrical equipment.

How long does a vaporizer battery last?

The manufacturers of the devices mentioned here do not state a general lifespan in years or charge cycles. How long a battery lasts depends on usage, temperature, charging behaviour and storage.

Arizer advises preserving battery performance by using the device at moderate ambient temperatures and lower temperature settings and avoiding extreme cold. The German Environment Agency advises avoiding complete discharging and charging. Smono names clear signs that a replacement is due: noticeably fewer sessions per charge or a device that switches off earlier at higher temperatures. Limelight deliberately built the Frolic with a replaceable battery so that you can replace the cell at the end of its service life.

Frequently asked questions

Can I use a 21700 battery instead of an 18650 battery?

No. A 21700 battery is thicker and longer than an 18650 battery and does not fit in a battery compartment designed for the latter. Only use the form factor that the manufacturer specifies for your device.

Is the battery covered by the warranty?

Each manufacturer decides this for itself. For the Air SE, Arizer explicitly excludes the battery from the one-year limited warranty. Check the warranty terms of your device.

Can I use my vaporizer while it is charging?

According to the manufacturer, this is intended for the Arizer Air SE, Air MAX and Solo II MAX. Charging then takes longer. For other devices, the information in the respective manual applies.

How can I tell that my battery should be replaced?

Typical signs are noticeably shorter usage times per charge or a device that switches off prematurely at higher temperatures. A swollen, deformed, hot or leaking battery must be removed from the device immediately and taken to a collection point.

How do I carry spare batteries when on the go?

Ideally individually in a plastic battery box, separate from keys, coins and other metal parts. This way you avoid short circuits at the terminals.

Are there vaporizers with a built-in battery?

Yes. According to the manufacturer, the battery in the Arizer Solo II MAX and the Arizer Solo III v2.0 is not user-replaceable. If replaceable batteries are important to you, look out for this information when buying.

As of: October 2026. Technical data according to the manufacturer; the instructions for your device are authoritative.

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