I’m sure everyone has experienced that sinking feeling when you try to use your (insert electronic device here) and you get a symbol that looks like the one to the right, or it just flashes and turns off. If you’ve just quit smoking, and that device is your APV, you might be in for some trouble.

I have a friend who vapes, and despite his tiny 350mAh eGo battery dying (literally) * every day* when he is trying to use it, he is absolutely

*bewildered*by why it won’t last through lunch. So today I explained it to him, and in the process I got to wondering how many vapers don’t know how to accurately estimate the battery life of their (specific) setup.

So let’s do that using my friend as an example.

We have this 350mAh eGo battery putting out (roughly) 3.3v, and a Kanger EVOD with a 1.8Ω atomizer head. So a quick trip to an Ohm’s Law calculator (or some math if you’re handy like that) tells us that this setup is drawing 1.8A.

The formula for estimating battery life is: **C / I * 0.7 = ABL**

**Capacity** (divided by) **Current Drain** (multiplied by) **0.7** (equals) ** Approximate Battery Life **(in hours)

Multiplying the result by 0.7 is a way to account for external variables (like temperature which can have an **enormous** impact on run time) that would be needed to get a more accurate estimate of run time. It is generally agreed that a 30% variance should cover most unknowns.

Since we’re not really going to be dealing in hours with vaping (the batteries we use just aren’t big enough), we need to alter this just a bit to get a run time in minutes (just multiply the result by 60).

So how long will this setup run approximately? 350 / 1800 * 0.7 = 0.136 * 60 = 8.16 minutes.

So why isn’t your little tiny 350mAh eGo battery making it through lunch?

Because you would need almost two of those to support the amount of vaping you’re doing.

This is also handy to know when trying to determine if your battery is degrading, or when trying to figure out how many batteries you’ll need to take on a trip with you. Unless you prefer to just load up * everything*.

Oh, and here is a handy online battery life calculator.