(11) Deeper Understanding of Mod Batteries - Part II
This is Part II of a Deeper Understanding of Mod Batteries.
Protected vs. Unprotected Batteries
There is a common misnomer in the vaping community that a protected battery is safer to use than an unprotected battery. There is a belief that a protected battery will prevent you from over-drawing your battery and prevent it to explode or vent gas. I'm not certain where this belief started, but it needs clarification. A battery labeled as "protected" does not always prevent you from applying a higher current draw than it is capable of handling.
The term "unprotected" is vague and often misunderstood. It can mean a "safe chemistry IMR or hybrid" that doesn't use a protected circuit, or an "unprotected ICR battery". Unprotected ICR batteries should NEVER be used in a mod; they should only be used in less demanding applications such as flashlights or laptops.
The protection circuits in batteries vary from manufacturer to manufacturer, but primarily prevent you from over-discharging (using the battery past its minimum charge rating) or over-charging the battery. The "protection" moniker is not all-inclusive either. Some will provide just over-discharge protection, others have over-charge protection, and in some batteries over-current protection.
You will have to hunt down the data sheet from the battery manufacturer to find exactly which protections are provided, or hope that your merchant has this listed online. Protected batteries are quite often longer in length than their unprotected counterpart. This is due to the additional circuitry that is embedded in the battery. Confirm measurements before you commit to purchasing.
Now, this said, lithium ion batteries have what's called a PTC or Positive Temperature Coefficient circuit. This is built into the battery just above the positive terminal and is present regardless of any "protected" labels. The PTC is designed to raise the resistance of the battery as the temperature of the battery rises.
The theory behind PTC is that as the resistance goes up, the current draw from the battery goes down - Ohm's Law. This helps prevent most accidents from becoming catastrophic, but it should not be relied on. The PTC is designed to be unobtrusive and you can still over-draw the battery if you aren't paying attention. The PTC circuits can also fail if exposed to static electricity or from a faulty charger. When a PTC fails, it often fails in a position which allows you to continue using the battery without fault.
Ohm’s Law 101
Ohm's Law defines the relationship between Voltage, Resistance, and Current, or: I = V / R.
V = voltage (volts)
I = current (amps)
R = resistance (ohm)
Before building your own coils, you should make yourself familiar with Ohm's Law. This will allow you to calculate the draw on your battery before you fire it up for the first time and potentially push the battery past its limits. Ohm's Law for Vapers
Ohm's Law Calculator
Basically, if I build a coil that has a resistance of 1.5ohms, and I apply 4.0v across it:
4.0v / 1.5ohm = 2.6 amps
This means you will have a 2.6 amp current draw on your battery. If I was using an ICR18350 (a low drain battery), I would be pushing the limits of the battery, while an IMR18350 (a high drain battery) would accept it with ease.
What exactly is an AW anyway?
AW are the initials of Andrew Wan, who owns a China-based company who at one time "allegedly" purchased large quantities of batteries from the better Japanese manufacturers and performed quality tests on each one because not all batteries are created equal. Once the battery passed the quality tests of AW's standards of quality, they slap on a new wrapper and add their AW label to it. When there were only ICR batteries available (before IMR), the label on AW batteries said, "Assembled in China, Cell and IC made in Japan". This seems to support the theory that AW batteries were "re-wraps".
The above rumors aside, I personally believe that AW is not re-wrapping batteries made by other manufacturers any more. I suspect that AW IMR batteries are manufactured by AW in China. I make this assumption because AW was the very first company to offer a high drain IMR battery on the market, and the Japanese manufacturers do not make IMR batteries in 14500, 18350, or 18490 sizes. AW does offer IMR batteries in this size, so who is actually manufacturing these cells? I believe it is AW. Plus, today's AW batteries say only, "Made in China".
What is a "Re-Wrapped Battery"?
There are many battery companies that are not actually manufacturers, but are simply brands. Meaning, they do not make their own cells and are just buying cells from other manufacturers and “rewrapping them” with their own case that has their own brand name and their own logo.
Most rewrapped batteries are Chinese brands. The first thing vapors must realize is that many of these brands have nothing to lose, and can make greatly exaggerated claims regarding performance with no bad fall back. For example ultrafire will claim 6000mah capaicty in cells that are tested to be only 1000mah. Of course the other grossly exaggerated stat is amp rating...and to sale to vapors, many of these companies will make outrageous claims.. We really recommend that the consumer stay away from all re-wrapped batteries. Here is a list of battery brands highly suspected of being re-wraps:
Inline fuses are becoming more popular as more people venture into the market of mechanical mods. Unlike regulated mods, mechanical mods have no built-in protective circuitry against short circuits. Inline fuses are small, disk-shaped components which you place inside your mod below the negative terminal on your battery. An inline fuse, commonly rated at 7 amps, will prevent you from accidentally pulling too much current from your battey either from device failure or low atomizer resistance.
Inline fuses are fairly inexpensive, but do add a small space requirement to fit into the battery compartment of the mod. If you are using a mechanical mod and you can fit one with your battery, I would suggest you add one to your setup. If you are using a regulated mod, an inline fuse is probably overkill as this kind of protection is already built into their processor circuitry. Both Smok and Vape Safe offer inexpensive inline fuses which are specifically designed for e-cigarettes..
Stacked or unstacked?
In some mods, you can fit two 18350's when the mod is configured for an 18650. This boosts the voltage output from 3.6V to 7.2V which means more vapor. Yay. BUT, you should NEVER do this. Unless you are familiar with matching batteries, you are only endangering yourself and others.
You may think, "Well, shucks, laptops have multiple batteries in them, why can't my e-cig?" Laptop batteries are specifically designed for stacking and are paired for use at the factory. When using un-matched batteries, they will discharge and provide current at different rates. This means one battery will continuously take more of the stress than the other.
You may not notice any trouble at the start, but as the batteries age with use the problem will become more severe. Push the batteries a bit further and now you've entered the realm of thermal runaway (see pics at beginning of this blog). Downside being that one battery entering thermal runaway will push the other battery into thermal runaway. Now you have two small, flaming explosives only inches from your face.
Serial vs Parallel Dual Battery Mods
Some mods are designed to use two 18650 batteries simultaneously. Series (batteries stacked end to end) will double the voltage output, but the capacity (mah) and amps will stay the same as using only one battery alone. Parallel (side by side) batteries will double the amp and mah capacity while the voltage output remains the same as using single battery. Serial and Parallel Battery Configurations
When a mod is hooked up in series, the voltage is added, while the amperage (current load) and mAh remains the same.
When you have a mod hooked up in parallel, the voltage is the same and the amps and mAh are added. Due to voltage drop and increased resistance in the wiring, the amp increase is only 1.5 times, not 2 times. (see below video and advance to the 15:40 mark)
Reversing Batteries in Mods
"Why do people want to insert batteries the wrong way round?
Perhaps because a battery that fails will vent first from the positive end - you can see the tiny gas vents around the positive terminal at the top. All rechargeables have these. Maybe the device being used only has gas vents at the bottom, so that the user assumes that it will be safer if the battery pos terminal is by the tubemod's gas vent.
There are so many faults in this reasoning that it is futile listing them and would take too much space. Just don't do it." ---Rolygate, ECF Forum administrator and battery expert.
How an 18650 Battery is Made
Choose your batteries wisely. Use the right battery for your specific applications. In this day of modern battery technology there is no reason to use ICR batteries in mods. If in question, for general applications you can't go wrong with AW IMR high drain batteries. If building sub ohm coils, use a 20 - 30 amp battery. Battery Basics for Mods
The above information was adapted and condensed from an article written by Timothy Braun, a vaper enthusiast and battery expert. - Batteries Explained and Safety - » The Original Electronic Cigarette Social Media Network
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