This is a guest post written by Morandir835, an e-cig enthusiast, admin on the Vapor4Life forum, and a regular on their ECF sub forum. A question that gets asked a lot in the ecig world is "How long will my batt last?" In some ways, this question is easy to answer, but impossible in others. Here are the key factors of what determines how long a battery will last. Understanding mah The first thing you need to understand is mah. Mah stands for milliamps hour (milliampere and is abbreviated as mA). This is the capacity of the battery. The higher the rating, the longer the battery will last. A 2000mah batt will last twice as long as a 1000mah batt under the same conditions. The next two factors are voltage and ohms. This determines at what amperage (amp) a battery is actually running. The higher the amperage, the less time the battery will run. Here's an example: If battery A is fixed to run at 5V, and batt B is fixed to run at 3.7V, and both are using a 3.0 ohm cartomizer, then batt A is pulling 1.67 amps, while batt B is pulling 1.23 amps. If both batts feature the same mah (600mah for this example), then batt B will last longer if used under the same conditions.
Vaping habits The other key factor in determining how long a battery will last, is how someone vapes. This is where things get complicated. The two ways to measure how long a battery lasts is actual run time and use time. Actual run times rarely get mentioned, because people tend to say what their personal use time is. In earlier blog posts I've mentioned that some people can go a full day on one XL batt, while others need 8-13 batteries to make it through the day. Vaping habits will be the determining factor in this. Here's an example: Say there are 3 people all using the same kind of battery, with the same mah, and same ohm cartomizer on it. Let's say the battery runs at 5V, the carto has 2.5ohms, and the battery has 2000mah. Person 1 gets 8 hours of use out of his batt. Person 2 only gets 4 hours, and tends to chain vape. Person 3 is not a heavy vaper, and gets 12 hours.  They also used a stop watch to keep track of every time their battery was actually in use. They got exactly 60 minutes of run time over that 12 hour span. All 3 people have one thing in common, they all actually only got 1 hour of actual run time from their battery. However, since their vaping habits differ, their real usage time was far different. This is why answering the question of how long a battery will last is impossible to answer. You can tell someone using a 400mah battery with a 2.3ohm carto on, with an average voltage of 3.85V that they will get 14 minutes and 20 seconds of actual use time, but you can't tell them over what time period they will spread that use out. If you have questions about this, or other battery questions, you can ask here in the comments section, e-mail me, or contact me through either V4L's or ECF's forums. Contact Morandir835 via e-mail at [email protected] or through his page on ECF at "Even Though I Nothing Learned, With Strength I Burned." - Emperor