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Battery Safety


A number of mods require removable batteries that are generally.  There are a number of safety issues associated with the use and storage of removable batteries that include but are not limited to the following:

  • Only ever use high quality products purchased from a reliable and reputable source and manufactured by trusted brands. Be extremely careful when purchasing cheap batteries, particularly online as many fake/re-wrapped batteries are often available that do not actually contain the battery chemistry as advertised.
  • Use the correct batteries. It is important to research and understand what types of batteries are recommended for your specific mod.
  • If your mod requires multiple batteries ensure that the batteries used are identical. Batteries used in a multiple battery device should be paired together, used together, charged together and discharged together.
  • Always check the condition of your batteries before use and look for any signs of damage i.e. dents, rips or tears in the insulation wrap. If any damage is discovered withdraw the battery from use immediately and dispose of safely. Damage to the wrap has the potential to cause a short circuit and can be extremely dangerous.
  • Never carry or transport loose batteries as accidental contact with another conductor can cause a short and has the potential to vent or explode. We recommend the use of safe insulated battery cases when transporting your batteries at any time.
  • Always ensure your batteries are stored safely when not in use. It is important that they are stored in a cool dry environment away from any conductors that have the potential to come in to contact with the battery.
  • Never under any circumstances immerse your batteries in water or allow them to come into contact with any liquids.


  • Check how your device/battery(s) is/are charged and ensure that you charge your device/batteries safely.
  • Mods with built in batteries are charged through the device and this is normally via a USB port and charging cable.
  • Other devices utilise replaceable rechargeable batteries that can sometimes be charged through the device and/or with the use of an external battery charger.
  • Some mods/devices, but not all, include a pass through “vape while charging” function. It is important to understand if your device is compatible with pass through before attempting to do so.


  • Only ever use the charger supplied with the battery to charge.
  • Always check the charging cable for damage prior to use.
  • Only every connect the charging cable to a power source that is the correct amp/voltage rating for the device and always consult the manufacturer’s user manual if unsure.
  • Never leave the device unattended whilst on charge
  • Ensure the connector on the charger is clean and free of any moisture before connecting to the battery.
  • Ensure micro USB charging cables are not damaged.
  • If the batteries can be removed and charged using an external battery charger we always recommend doing so over charging through the device.
  • For devices that use multiple batteries and support in-device charging is it strongly recommended to use and external charger as charging through the device often does not distribute the power evenly to each battery which in turn can have a detrimental effect on the lifespan of the batteries.


  • Only ever use high quality battery chargers purchased form a reliable and reputable source  and manufactured by trusted brands.
  • Ensure that your charger rating is suitable for the batteries being charged.
  • Always use chargers that include automatic cut off once fully charged to prevent potentially dangerous overcharging.
  • Never leave batteries unattended whilst on charge.
  • Always check your charger for any sign of damage and that it appears to be working correctly. Do not use if there is any damaged to the charger, cable or components.
  • Ensure the contacts on the charger and batteries are clean and dry at all times.


Understanding Ohm’s Law is absolutely essential and the most important consideration when safely using an unregulated mod. We have given an outline of the essentials points to be understood but if you are in any way uncertain we strongly recommend that you carry out further learning and research on the subject prior to the use of any unregulated device.


Ohm’s Law is the relationship between power (W), voltage (V), current (I), and resistance (Ω). When used in vaping, it is mainly considered in regards to the amp of the battery.

A battery’s amp rating is the current of the battery or the ability of the battery to release the electrical energy stored within it. When using an unregulated device, the amps drawn from the battery is dependent on the resistance of the coil. If the battery is pushed beyond its limit, the battery can vent. When a battery vents it releases or leaks hot dangerous chemicals, that if unventilated and unable to escape has the potential to explode.

When using an unregulated device it is imperative that the resistance of the coil will not draw more amps than the battery contains. You can calculate what amps the coil will pull from the battery by using the simple equation:

Amps (I) = Voltage (V) / Resistance (Ω)

A single 18650 battery generally has a maximum voltage of 4.2v when fully charged and a nominal voltage of 3.7v. Always air on the side of caution when calculating the amps drawn by using the upper limit of 4.2v. You should always use a multimeter to find out the voltage of your battery prior to use in an unregulated device.

The resistance of the coil is measured in Ohm’s (Ω) and can be determined by using an Ohm’s reader which is an essential piece for kit for building coils to be used on unregulated devices.

Once you know both the Voltage and Resistance you are able to calculate the amps drawn from the battery. For example, using a fully charged 4.2v 18650 battery and a 0.3Ω coil:

Amps (I) = Voltage (V) / Resistance (Ω)

Amps (I) = 4.2 / 0.3

Amps (I) = 14 Amps

The calculated 14 Amps is the Amps that will be drawn from the battery. If the calculated Amps drawn is below the rated amps of your battery then this indicates that the battery has sufficient discharge capacity for the resistance of the coil. However, you should never use a coil resistance that pushes the battery to its limit and we strongly recommend always using a build that draws a minimum of 5 Amps less than the battery is rated for.

If you require further help to understand or practice Ohm’s Law calculations we recommend using an online calculator tool like steam engine. Failing to follow this advice when using an unregulated mod at a level that exceeds the battery’s upper amp can cause short circuiting of the battery and as outlined above has the potential to cause the battery to vent, damage the mod and even explode. If venting of the battery occurs for any reason your batteries are dangerous and must be disposed of safely.


Unregulated devices and in particular Mechanical mods should only be used by experienced vapers that understand the battery safety outlined in this section. There are some further considerations that are important to be aware of when using mechanical mods:

  • Only use a mechanical mod if it has vent holes to allow venting of the battery. These holes allow gases to escape the mod if the battery fails and “vents”. Always check the vent holes are working prior to use by removing the batteries and blowing into the mod from the connection end. You should be able to freely blow through the device.
  • Do not over-discharge the batteries. There is no charge indication in a mechanical mod and the user is responsible for knowing when to stop using and recharge the battery. If the battery is too low for too long it will have a significant detrimental effect on the lifespan of the battery and will cause the battery to fail.
  • Check the voltage of the battery and recharge any batteries with a resting voltage of less than 3.7v.
  • Never transport mechanical mods or leave them unattended with the battery installed. Many mods have sensitive firing buttons that can easily be engaged accidentally. With no automatic cut off this can lead to overheating, venting, explosion and has the potential to cause fire.


The information given in this section is for advice only and the use of any device(s) purchased from Zapp Cardiff Ltd is done so at the purchaser’s own risk.

Rebuildable atomizers and unregulated devices are strictly to be used by by experienced vapers ONLY that have sufficient knowledge and experience in safe coil building, Ohm’s Law and battery safety. Reading this section on Battery Safety should not be considered sufficient knowledge for the safe use of any device. Please ensure care is taken as to not cause damage or harm to the atomizer, vaping device, or yourself and others.

Zapp Cardiff Ltd is not responsible for the safe use of any products and will not be held responsible for any harm or damage caused as a result of improper use.