(11) Deeper Understanding of Mod Batteries - Part II
by, 10-24-2013 at 08:52 PM (8274 Views)
This is Part II of a Deeper Understanding of Mod Batteries.
Sony VTC5 IMR/hybrid battery
Hybrid batteries are a new type of "mixed chemistry" battery manufactured by Panasonic, Sony, Samsung, and others. Hybid batteries use a Cobalt cathode like ICR batteries but have the same manganese and nickle makeup which IMR batteries have. This provides for higher drain capabilities while also having higher overall battery capacity (mAh).
Note that not all Panasonic NCR batteries are considered "high drain". Panasonic NCR18650B 3400 mAh and NCR18650A 3100 mAh were designed and best suited for applications like a flashlight and not mods.
Hybrid batteries are capable of a much lower minimum discharge voltage before causing physical damage to the battery. The battery is capable of being discharged to 2.5V whereas IMR/ICR batteries have a cutoff around 3.2V.
Protected vs. Unprotected
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.
Ohmís 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)
If you are 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.
You Tube Video: Explanation of Ohm's Law
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, I would be pushing the limits of the battery, while an IMR18350 would accept it with ease.
What exactly is an AW anyway?
AW are the initials of Andrew Wan, who owns a China-based company which purchases large quantities of batteries from the big boys (Panasonic, Samsung, etc) and performs quality tests on each one. Not all batteries are created equal. Once the battery passes the quality tests, they slap on a red wrapper and add their AW label to it.
The reality is that internally, a battery labeled AW and a battery labeled Panasonic, Samsung, etc are the exact same thing. Aw has just run his through a foray of tests and then sells the best ones as AW. Does it make their battery safer? Not exactly. Does it help ease the mind? Absolutely.
Inline fuses are becoming more popular as more people venture into the market of rebuildable atomizers. 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 have small space requirements 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 like a Vamo, ZMax, Provari, etc, an inline fuse is probably overkill as this protection is already built into their processor circuitry. Both Smok and Vape Safe offer inexpensive inline fuses which are specifically designed for e-cigarettes..
Vape Safe Mod Fuse
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.
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, you can't go wrong with AW IMR high drain batteries. If building sub ohm coils, use a 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 - Ľ The Original Electronic Cigarette Social Media Network