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Battery Safety: Will You Marry Me?

Article supplied courtesy of:

Author Tim Mechling

I hope you enjoyed this article. Battery safety can be hard to understand and cumbersome to talk about, but it is by far one of the most important aspects of vaping. Please share this information with all of your closest friends and help spread awareness about battery safety. If you’re looking to pick up some new ones, I highly recommend these available on our website. Stay safe and happy vaping!

Batteries, batteries, batteries: so many to choose from. How do you know which one is right for you? Well, call me the matchmaker, because I’m here to help you decide! Before you can find your mate, you’ll need to learn a little about what makes them tick.

BATTERY MARRIAGE

“Married” batteries means 2 batteries together for their whole life. They can go in different mods as long as they are never split up. They should be discharged and recharged at the same time, every time. If your mod is configured in series, then you should also rotate the position of the batteries each time. This is because the first battery in the series will take the brunt of the force so you want to alternate the duties of your batteries. If an old and a new battery are used together, it’s possible for the old one to be discharged below the normal 3.2v causing damage to the battery and maybe your device. You will also reliably get the same number of charges from both, and know when they are both at the end of their life using the married method.

BATTERIES AT A GLANCE

First of all, how does a battery work? Well, without getting too complicated, the battery is made up of stacked “cells.” Each cell has a negative terminal and a positive terminal immersed in an electrolyte solution. When you put your battery in a circuit, an interaction between chemicals occurs. This causes positively and negatively-charged ions in an electrolyte solution to want to move to a terminal on each side of the cell known as an “anode” (negative terminal) and a “cathode” (positive terminal). This movement of ions allows energy to flow to an external device, powering it. When you charge a battery, you reverse the chemical reaction used to discharge the cell, literally resetting the ions back to the way they were. Ultimately, a little is lost in the process of resetting each time you do it. Eventually, the chemical reaction will no longer occur. This is why batteries have to be replaced and cannot be recharged forever.

Now, I want to quickly talk about differences in quality. You need to understand that not all companies are equal. There are battery makers that are notorious for mislabeling their batteries or claiming they can handle higher loads than they really can. Stay away from any brand with “fire” in the name, as a general rule. I suggest using one of the top 4 brands; Efest, Samsung, LG or Sony. And make sure you’re getting them from a reputable company because just as they will misstate the ratings they will sometimes outright claim to be a Sony or whatever but are actually knock-offs or counterfeits.

CRUNCHING NUMBERS

So, there’s a lot of different numbers on a battery. What do they all mean? Let’s start with the number that determines the physical size of the battery. The number is 5 digits that together, spell out the dimensions. The first 2 are the battery’s diameter (in mm) and the last 3 are the battery’s height (in 10ths of a mm). So using an 18650 as an example: 18mm in diameter, 650 tenths of a mm (ie 65mm) in height. This is the first limitation to consider when selecting a battery for your device. In many ways, this will ultimately determine the capacity the battery can store. The chemistry inside is also a huge factor as two 18650 batteries can (and most likely will) have different internal designs but generally, the bigger the battery, the more cells you can fit inside. 18650 is definitely the most popular, but other sizes exist for smaller or larger devices, so make sure your battery compartment will hold the size you want it to (measure it if you’re unsure).

Next, there is a letter code that represents the chemistry interacting inside the battery. The ones we use in e-cigs are Lithium Ion Batteries which are inherently safe. The most common ones you’ll see (and want to use) are; IMR- Lithium Manganese and INR- Lithium Nickel. The nickel/manganese is what the cathode is made out of in these examples using these different materials yields different results. For example INR can typically have a higher capacity, but suffers from not being able to handle as high of a load as IMR.

BATTERY VOCABULARY

To talk more about batteries, we’ll need to define a couple words. Electricity is a hard thing to describe, so most people find it helpful to compare it to something we can see. Imagine a series of pipes connected in a loop with water running through them while we define these words.

(V)Volt

THE POTENTIAL OF ELECTRICAL ENERGY IF IT WERE ALLOWED TO FLOW FULLY. USING OUR ANALOGY, THIS WOULD BE THE WATER PRESSURE.

(I)Current T

HE FLOW RATE OF THE ENERGY AND IS MEASURED IN AMPERES. USING THE SAME EXAMPLE, AMPS WOULD BE THE RATE THE WATER IS FLOWING.

(R)Resistance

A MATERIAL’S OPPOSITION TO ELECTRICAL ENERGY, MEASURED IN OHMS. AGAIN, USING OUR EXAMPLE, THIS WOULD BE THE THE SIZE OF THE PIPE.

Ohm’s Law- I=V/R

A SYSTEM USED TO CALCULATE THE RELATIONSHIP BETWEEN THESE 3 THINGS. OHM’S LAW STATES THAT IT TAKES 1 VOLT TO PUSH 1 AMP THROUGH 1 OHM OF RESISTANCE. TO RELATE THIS TO OUR EXAMPLE, LET’S SAY IT TAKES 30 PSI (POUNDS PER SQUARE INCH) OF PRESSURE TO PUSH 1.3 GALLONS PER MINUTE THROUGH A PIPE THAT’S .31” IN DIAMETER (THIS IS TRUE BY THE WAY). CHANGING ANY OF THESE 3 THINGS WILL AFFECT ONE OF THE OTHERS. IF YOU USE MORE PRESSURE ON THE SAME PIPE, YOU’RE GOING TO GET MORE GALLONS PER MINUTE. IF YOU WANT MORE GALLONS PER MINUTE BUT KEEP THE PRESSURE THE SAME, YOU’RE GOING TO NEED A BIGGER PIPE.

MILLIAMP HOURS (mAh)

This DOES NOT stand for Milliamps per hour. This is one of the most common errors I see. It stands for Milliamp Hours. For an example let’s say a battery is 2000mAh. This means that if the battery were in a circuit that only drew 1 milliamp, it could power it for 2000 hours. Unfortunately for us, our ecigs usually draw more than one milliamp. My setup is drawing 7.4 amps. Which means that it can run for 16 minutes of vape time total. Since I take about 3 second puffs, that’s 324 draws until it is dead. While we’d all love to have a 10,000mAh battery, usually a higher mAh means sacrificing some of your amp limit.

Voltage

3.7V IS THE STANDARD OUTPUT FOR A FULLY CHARGED BATTERY. THIS IS IT’S “UNDER LOAD” VOLTAGE. AS YOU USE THE BATTERY UP IT LOSES VOLTS. LETTING IT FALL BELOW A CERTAIN POINT CAUSES INTERNAL DAMAGE TO THE BATTERY. THE MOST POPULAR REGULATED DEVICES DON’T LET THIS HAPPEN. THEY WILL STOP ALLOWING YOU TO FIRE AT AROUND 3.2V. KEEP IN MIND THAT IF WE’RE TALKING ABOUT MECHANICAL MODS, THIS IS GOING TO DIRECTLY AFFECT THE PERFORMANCE OF THE VAPE. USING OUR EXAMPLE, YOU’RE STILL USING THE SAME PIPE SIZE (RESISTANCE) BUT YOU’VE DECREASED THE PRESSURE (VOLTS) SO YOU’RE GOING TO GET LESS GALLONS PER MINUTE (AMPS). WITH REGULATED MODS, YOUR PERFORMANCE WILL NOT BE AFFECTED UNTIL THE BATTERY DIES, BUT THERE ARE DIFFERENT THINGS GOING ON INSIDE. WHEN YOU TELL THE DEVICE YOU WANT A CERTAIN END RESULT (WATTS) IT TAKES WHAT IT IS GIVEN AND AMPLIFIES IT TO REACH THAT RESULT. SO, AS YOUR BATTERY DIES, IT DRAWS MORE AMPS FROM YOUR BATTERY TO MAKE UP FOR THE LOSS IN VOLTAGE ACCORDING TO OHM’S LAW.

Amp Rating

There are two ratings, and you need to know the difference between. Pulse rating and continuous rating. Pulse rating is the amps you can safely draw if you were only doing it for just a moment, like fractions of a second. Continuous rating is the amps you can safely draw indefinitely until the battery runs out. Both of the ratings are essentially based on how hot the battery will become and whether or not the internals would fail at that temperature, causing them to vent. Generally, you don’t want your batteries to be hot or even warm. In vaping, we use the continuous rating for 2 reasons. One is that three seconds (an average draw) is certainly longer than what “pulse” covers. The second is that if your mod or the switch on it should somehow fail and continuously fire, you want to be within your continuous limit. Since my Efest IMR 18650 2500 mAh battery has a continuous rating of 20a, we will use it for examples from here on.

So, how do you calculate your amps and determine if you are being safe? Well, if you’re using a mechanical mod it’s easy-peasy, just use ohm’s law above. When you’re using a regulated mod, things get a bit tricky, but here’s the equation you will want to use: I=P/V where P is the maximum watts you want to get. Let’s say 40 watts. I=40w/V. Here’s the part where you need to pay attention: V is not a constant number. Your volts go down as the battery is depleted, so when you’re calculating this, you want to use the volts for an almost dead battery, (since that’s what it will eventually be) 3.2v for practical application, 2.5v if you want to be extra safe. So if I=40w/3.2 or I=12.5, my setup is well within the safe zone. What happens when your mod takes multiple batteries?

MULTIPLE BATTERIES

Multiple battery mods are configured in 1 of 2 ways. These are called series and parallel. A series connection will treat 2 batteries as 1. The voltage is doubled but the capacity and amp limit remain the same. A parallel connection will double the capacity and amp limit but still only deliver 3.7 volts on a full charge. They ultimately work to achieve the same end result, but they do it in different ways. Let’s look:

Series: I=80w/6.4v (3.2v times 2) I=12.5 Amps. You are within your amp limit.

Parallel: I=80w/3.2v (V does not double in parallel) I=25 amps. Uh-oh! Are we over our limit? Nope, remember that in parallel the capacity and amp limit are doubled.