How do you work out how long an e-cig battery might last before it needs a recharge?

How many of you look at the technical information on the website and have absolutely no idea what a 650mAh battery means, so you look to the blurb to find out how long it will last?

Read this, and you’ll understand it all, (and look pretty smart in front of your friends too).



Please note I have taken a lot of this information from another vape blog – the link to it is at the bottom – as this is such great information, very easy to understand, so I thought it would be good shared here too. I have taken the salient points and done a précis, but you can read the full blog from the link at the bottom.


The précis:


The e-cig used in this example has a 650mAh battery – (like the Tornado) is rated as 3.3 volts output, and uses a cartomiser of 2.5ohms resistance. You will need this info from your e-cig; battery, voltage and cartomiser ohm to work out your battery length.


OK, when a battery says its 650mAh, what it is telling you is that it will put out 650milliamps per hour of energy, after that it will be drained. What it doesn’t tell you is how long it will last when faced with resistance and someone vaping away on it.


This is where the maths and those figures comes in:


We use Ohm’s law to work it out. Ohm’s law states that the current drawn equals the voltage, divided by the resistance.


When we apply this to our Tornado e-cig, the maths will look like this:


The voltage of 3.3 is divided by the resistance of 2.5 ohm, which = 1.32 amps – which is the current drawn.


We then fiddle about with the decimal place so we can compare that current to our 650mAh battery – and 1.32 amps becomes 1320 milliamps.


We then divide the 650 milliamps per hour by the 1320 milliamps per hour and get 0.49 of an hour – which is just under 30 minutes.


(If you didn’t get that first time round  – go back and read it again).


This does not mean that your e-cig will only last 30 minutes from the moment you charge it, what it means it that it will deliver 650milliamps to your e-cig continuously for 30 minutes. But no one vapes continuously for 30 minutes, (or at least I hope they don’t) and this is where the variables come in, such as:


How often do you vape? How long are your inhales? How long do you keep the button pressed with a manual?  All these add up – you may only inhale for 3 seconds, have 10 inhales and then leave it for an hour, or you may inhale for 5 seconds every 2 minutes. It the time in use that counts, and this will gradually add up throughout the day.  Most vapers will get around 6 plus hours from the time they screw on a new, fully charged Tornado before having to recharge it.


p.s. batteries age, and with age the milliamp goes down too.





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