Why does my e-cig battery die so fast?

There are several reason why your e-cig battery might be dying so quickly. Over charging, over discharging, incorrect storage, low resistance atomizer coils and wattage being set too high can all contribute to an e-cig battery not lasting as long as you might expect.

Let’s take a closer look at e-cig batteries and examine in detail some of the reasons for short battery life.

What are the different types of e-cig batteries?

E-cig battery types
Integrated e-cig batteries are integrated within the body of your device and cannot be removed. These are charged using an on-board USB port and usually feature passthrough charging, which means you can continue to vape while your e-cig is on charge.

Removable batteries can be taken out of your device to charge them. Some can be charged within your device using an on-board USB port, but it is normally advised to remove them and use an external charger.

No matter which type of battery you choose, your e-cig will either have settings to adjust or it will be a simple press and go e-cig.

If there are no settings to adjust it will have either a direct output or fixed output. This means you have no control over what power the battery provides. It is either determined by the voltage in your battery, it has a pre-set power output or determined by a combination of battery voltage and the resistance of the atomizer head fitted.

If there are settings to adjust it will either be variable voltage, variable wattage, variable temperature or a combination.

These settings will have a direct effect on your battery, we will look at these in more detail later.

What does a removable e-cig batteries name mean?
Removable e-cig batteries have names and terminology that are a series of letters and numbers. For example: 18650 2100mAh IMR. These are not random and all have meaning, let’s have a look at the individual components.

The set of letters refer to the chemistry of the battery, below are some of the most commonly used.

I = Lithium Ion (Li-Ion). Outputs a high nominal voltage of 3.7 volts, zero memory effect, high energy density and a high number of charge/discharge cycles.

C = Cobalt. Cobalt delivers high energy density for increased mAh rating, also offers a long lifespan.

M = Manganese. Manganese offers low internal cell resistance to enable fast charging and higher discharging rates while maintaining low temperatures.

F = Iron “Fe”. Iron is more tolerant to being stored at full voltage for prolonged periods of time, it suffers from a lower nominal voltage of 3.2 volts.

N = Nickle “Ni”.

R = Round or rechargeable.

The first two numbers refer to the diameter of the battery, the last three numbers refer to the length of the battery. Below we break down the most common external e-cig battery the 18650:

18 = diameter of battery 18mm, making the first two digits the diameter in mm.

650 = length in tenths of millimetres 65mm.

What is e-cig battery mAh?
mAh stands for milliampere hour.

An amp is a measure of electrical current, and the hour indicates the length of time that the battery can supply this current. A 2.2Ah (2200mAh) battery can supply 2.2 amps for an hour.

All things being equal, the bigger the mAh rating of a battery the longer it will last. For example, if you have a mod that has an integrated 5000mAh battery and you set it to output 30 watts, it will last twice as long as a mod that has an integrated 2500mAh battery if the output is also set to 30 watts. However, in the e-cig industry things are never quite so simple, other factors such as an atomizer head resistance along with fixed output or direct current mods will also have an impact on battery life.

You can however use the mAh rating to calculate approximate battery life, which we will discuss further later on when we look at ohms law.

What is Ohms law?

V = R*I
(V = Voltage, R = Resistance, I = Amperage)

Ohm law states that voltage equals the resistance multiplied by current.

Ohms law is a formula used within electronics and physics to determine current, voltage, power or resistance in a circuit. An e-cig is a circuit.

An atomizer heads resistance is only a factor concerning battery life when using a direct current/bypass kit or mechanical mod.

The following formulas are of interest to us are:

I = V/R. To calculate the current drawn from the battery if using an unregulated/bypass/mechanical mod such as an Ego AIO, divide the voltage (3.7) by the resistance of the atomizer head fitted (1.5). The higher the current drawn, the faster the battery will discharge.

I = P/V. To calculate the current drawn from the battery if using a regulated mod such as an Arc 4, divide the voltage (3.7) by the resistance of the atomizer head fitted (1.5). The higher the current drawn, the faster the battery will discharge.
Lower current drawn = longer battery life, higher current drawn = less battery life.

Now we have looked at some of the e-cig battery basics, let’s see how some of these things can affect your battery life.

Vaping settings
To simplify things, if using a kit that allows you to adjust the wattage or voltage, the higher you set your voltage or wattage, the faster your battery will discharge.

I = P/V
(I = Amperage, P = Power, V = Voltage)

Atomizer coil resistance
If using a direct current/bypass kit or mechanical mod, atomizer head resistance will play a big part in battery life. The lower an atomizer heads resistance, the more power is generated at the coil, higher power = more current drawn from the battery to heat the coil meaning less battery life.

P= V ²/R
(P = Power, V = Voltage, R = Resistance)

Example 3.7 * 3.7 / 0.5 = 27 watts of power
Example 3.7 * 3.7 / 1.8 = 7.6 watts of power

Charging and over charging your e-cig battery
Some common sense needs to be applied when we are talking about charging your battery. Only use a high quality charger purchased from a reputable source.

Do not over charge your batteries. Leaving them on charge all day might seem like a good idea, it means you’re guaranteed to never be caught short with a cell with low voltage, but means you’ll massively reduce the overall lifespan of the cell. The two biggest enemies for overall cell lifespan if using lithium ion batteries are being stored at maximum voltage for sustained periods of time and excessive heat.

Discharging and over discharging your e-cig battery
When you buy a new phone or laptop, the instructions will tell you to fully charge your battery then drain it completely before recharging. This is because that type of battery has something called a ‘charge memory’ so you need to ‘train’ them. Modern e-cig batteries do not have this internal memory, therefore you do not need to fully deplete them.

Over discharging your battery is more damaging as over charging it. If an e-cig battery is over discharged it’s no longer safe for use and must be properly disposed of, if you attempt to recharge an over discharged a real safety issue could arise. Luckily, most modern e-cigarettes how a minimum voltage cut off to prevent the cells from ever becoming over discharged. This does not apply to mechanical mods however.

How long does an e-cig battery take to charge?
The length of time it takes to charge your e-cig battery is determined by several factors.

If charging the batteries in the kit or mod, the charge time will be restricted, as all kits have a maximum charge rate, some older kits are limited 250mA, while newer kits allow the battery to be charged up to two amps, the higher the maximum charging current, the faster the battery will charge.

If charging removable batteries in an external charger, the charge rate can adjusted on some models. Usually the charge rate can be cycled from 0.5amp up to 2.0amps.

Using these guidelines and a simple calculation you can work out roughly how long your battery will take to charge.

mAh rating of battery ÷ charge rate (in mAh) x 60


A 2100mAh battery charged at 2amps (2000mAh charge rate)

2100 ÷ 2000 = 1.05 (minutes). 1.05 x 60 = 63 minutes.

Storing your e-cig battery
If you have an external battery and you need to store it outside of your e-cig, remember to use an appropriate battery case or sleeve to stop any damage to the cell. We will talk further about battery safety later on.

Note: Storing your e-cig battery in a dedicated non-conductive package minimizes potential risks.

Is the temperature of my e-cig battery important?
In short, yes. Extremely hot or cold can affect the chemistry within the cell and cause the cell to degrade, this is particularly true in hot conditions. The optimal temperature range is between 20°C (68°F) to 25°C (77°F). Again, the two biggest enemies for overall lifespan are being stored at maximum voltage for sustained periods of time and excessive heat.

Why does my e-cig battery get hot?
There are several reasons why an e-cig battery can get hot.

When using a regulated kit and setting a high wattage can cause the e-cigs internal chipset to draw a high amount of current from the batteries. This is to supply the amount of voltage needed to generate the high wattage, the higher the amount of current drawn, the warmer the batteries will become.

If using a direct current kit or mechanical mod and using a low resistance atomizer head, the lower the atomizer heads resistance, the more power is produced, more power is generated by drawing more current, more current means more heat.

Excessive use. If chain vaping, current is constantly being drawn from the battery, as current is drawn from the battery, the temperature of the battery will continue to increase.

Why does my e-cig battery keep flashing?
Kits that don’t have a display screen still need a way to indicate of any errors that occur. The battery flashing is usually an indicator that there is a problem. The most common errors are:

Atomizer head short circuit.

Low battery voltage.

Atomizer head resistance error.

E-cig battery charging cycles
As well as all the above factors, we need to take into account that all batteries have a life. No battery lasts forever, and they have a finite number of ‘charging cycles’, once this has been reached they will all start to exhibit symptoms of reaching the end of their natural life. Charging a battery to approximately 4 volts will give a massive increase in overall battery lifespan but will not last as long between charging. If you find that your battery is exhibiting these symptoms then it may be time to buy a new e-cig battery, or invest in a new e-cig kit.

E-cig battery safety

Battery Safety Guide
Lithium Ion batteries are safely used in literally millions of devices every day. However there are some risks associated with such high energy devices that users should be aware of. Batteries can present a fire risk when short-circuited, over-charged, submerged in water or if their cases are damaged. Although many Lithium Ion batteries are “protected”, the following cautions are still relevant, as the protection circuit is a potential safety mechanism rather than something that should be relied on. Li-Mn batteries (“IMR”) present safer chemistry and less fire-risk, but are capable of delivering very high power in a short burst. If short-circuited, the metal causing the short can get hot very quickly, which may lead to other damage or secondary fire-risks.

Always buy from a reputable vendor that is proud of the quality of their goods.
Check that the product or packaging displays the correct CE and ROHS safety markings and that the distributor can prove their authenticity.

Do not store, use or charge batteries in extremes of temperature, high or low. Only use charging equipment in good condition and specific to your battery type. Never mix batteries from one manufacturer with a charger from another without specific confirmation of compatibility.

Always charge batteries specifically as directed in the product instruction manual.

Do not leave charging batteries unattended, and always charge batteries away from flammable materials.

Transport loose batteries properly separated in non-conductive (e.g. plastic) containers, and never where they can come into contact with metal items that can cause a short circuit (e.g. pockets full of loose change or keys).

Do not use batteries with visible leaking or mechanical damage to the case, insulation or terminals.

Do not continue to use batteries that have ceased to function normally.

Do not submerge batteries in water. Batteries should be disposed of and recycled in accordance with your country’s appropriate legislation.

Learn more about e-cig batteries
This was a brief look at electronic cigarette batteries, how they work and why they might die so quickly.