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Ohm's Law 101 and E-Cig Tech: Understanding Vape Electrical Lingo

June 19, 2018

profile view of man exhaling red vape cloud

The Physics of Electricity and E-Cigs

For newcomers in the vaping community and even seasoned vaping veterans, the multitude of devices, batteries, and coils available can be overwhelming. At Velvet Cloud, we love to point out that vaping is a world of choices. This post will help vapers at every level make informed decisions about the electrical configurations they can use to enhance the enjoyment of Velvet Cloud's 21 signature flavors. 

How important is it for vapers to have a basic understanding of Ohm's Law and e-cig tech? In our recent blog post, Velvet Cloud exposed the vaping popcorn lung myth. In the course of tracing the source of that notorious misinformation campaign, we discovered that the most famous "victim" associated with popcorn lung (with some gory photos) had actually used incompatible parts to assemble a jerry-rigged vaping contraption which subsequently exploded in his face when he used himself as a lab rat to test out the perilous gadget. 

E-cig accidents are most frequently caused by the rechargeable batteries vaping devices use. Some overly enthusiastic newcomers dive into the vaping world. They are understandably eager to leave the hazardous habit of smoking combustible tobacco behind them, without taking some time to learn the basics of e-cig and rechargeable battery safety. Others are looking to take vaping fun to the next level with rich voluminous clouds. Or perhaps you're looking for more discreet vaping without drawing attention with huge aromatic clouds. That's where Ohm's Law for vapers comes in.

Once you have a grasp of this fundamental but simple electrical principle you can make informed decisions about sub-ohm vaping, cloud chasing, and all-day vaping hardware configurations that are safe and best-suited to fit your vaping budget. If your e-cig has adjustable power settings, Ohm's Law eliminates the guesswork so there is less trial and error as you experiment with settings to find your personal best vaping experience. And you thought you'd never use algebra in your everyday life! No need to flip out. Ohm's Law is algebra in its simplest form, so you don't need to be a math whiz to make it work for you.

Thankfully, e-cig accidents are rare. Unfortunately, like plane crashes, when one does occur it tends to make headlines that become fodder for anti-vaping media cannons. Disreputable clickbait websites are also eager to use these incidents to pluck some low-hanging social media fruit to attract more hits, as they did with the popcorn lung myth. We don't need to give them any more ammunition. So before we delve into Ohm's Law and its applications for vaping, let's review some battery safety basics and best practices. 

Battery Safety

Batteries are the most common culprit in vaping device accidents. Battery explosions are often caused by overcharging, incompatible chargers, or improper handling such as carrying spares in the pocket with the terminals exposed to other metal objects like car keys and coins, as one Kansas man found out the hard way.

Improper storage such as cooking the battery in a hot glove compartment or tossing exposed spare cells together haphazardly is asking for trouble. (Though the thermal risk is low for lithium-ion batteries, there is some risk.) There is an electrical phenomenon called "thermal runaway" also known as "venting with flame," which is a vivid example of Ohm's Law in action.

Heat lowers resistance, which increases current, which causes more heat, which lowers resistance even further, which increases the current even more and on and on until the battery components finally reach ignition temperature and detonate. Traditional lead-acid batteries, such as car batteries, have the added hazard of venting hydrogen which intensifies the detonation. Remember the Hindenburg? One big bag of hydrogen and one small static electricity discharge (some theories claim) was a disastrous combination.

Fortunately, vapers, cell-phone owners, and laptop computer users don't need to walk around with dangerous 12-Volt lead-acid car batteries strapped to their backs, thanks to advanced rechargeable battery technology. These little jewels liberate power tools from the need for electrical outlets that power everything from emergency flashlights to GPS gadgets, allow us to access apps and the internet anytime from anywhere, and soon they'll replace gasoline as the green power source for our cars. 

Lithium-Ion Batteries

Two billion lithium-ion battery cells are produced each year. Lithium has been known to be a potent source of battery energy since research began way back in 1912. Lithium metal batteries provided very high energy density but lithium metal is also unstable during charging. These metallic lithium batteries were replaced by much safer lithium-ion batteries after a cell phone exploded in a man's face and triggered a massive lithium metal battery recall back in 1991. 

According to this informative report at Battery University, "Today, lithium-ion is one of the most successful and safe battery chemistries available."

Though the risk of explosion is very low, there are some best practices we can use to ensure that it stays low. 

Lithium-Ion Battery Safety Tips 

  • READ THE OWNER'S MANUAL for manufacturer's recommendations about charging and discharging limits and charger recommendations.
  • Carry spare batteries in a plastic storage case if you must carry them in your pockets. This protects against electrical shorts from coins or keys which could trigger a thermal runaway event.
  • Avoid overcharging and use protected batteries which automatically stop the charge when the maximum capacity has been reached. The small circuit board in the pack also protects against over-discharge, short circuits, and overheating.
  • Use the appropriate compatible charger only! The wrong charger can damage the protection circuit. Though the battery may still function, it is now vulnerable to all the hazards above. 
  • Don't overwork the battery. If your e-cig or mod is heating up and staying warm after time has passed since the last vape, it may be time to replace the battery. There could be a venting problem which is preventing the system from cooling down, or the e-cig or mod itself is faulty.
  • NEVER puncture the battery with a tool or nail. This is one of those common sense survival rules in the same vein as "Don't hit a shotgun shell with a sledgehammer." 
  • Use factory wrapped batteries from reputable manufacturers. Avoid rewrapped and no-name bargain basement batteries. Unwrapped batteries are subject to metallic contamination which destabilizes the lithium-ion chemistry.
  • Don't charge below 32 degrees F. Plating on the anode can occur permanently compromising the safety of the pack.

Battery and coil safety is easy to understand once you have a basic knowledge of the interactions between voltage, current, and resistance as they are defined by Ohm's Law. First, a brief bit of history concerning some common electrical terms before we get into the real egghead stuff. 

colored vape atomizer boxes on white surface closeup

 George Ohm and His Law

Ohm's Law was named for the German physicist George Simon Ohm who discovered it way back in the 19th century. Ohm's Law states:

"The current flow through a conductor is directly proportional to the potential difference (voltage) and inversely proportional to the resistance."

The "ohm" is named after George and is the unit of measure for a component's resistance. If we know the value of any two of the electrical values we can calculate the unknown third value.

Every electronic device in the world today owes its existence to George Ohm's legacy in the science of physics, but ironically, Ohm's Law did need to overcome some resistance itself. The German mathematics professor's work was so groundbreaking back then that it received a cold shoulder from a skeptical academic community, causing the disgruntled genius to resign his post.

Later in 1841, George Ohm was at last duly recognized for his achievements when the Royal Society of London awarded him the prestigious Copley Medal. Considering the contributions to science Ohm has made, by George, we think he deserved it. (groan!)

Volts and Voltage

The term "volt" is the namesake of Alessandro Volta, an 18th-century Italian scientist who stacked up a pile of zinc and copper disks separated by saltwater-soaked paper discs, and thereby invented the first voltaic pile. In 1748, Ben Franklin popularized the term battery bringing to mind a collection of things used together such as a battery of artillery. Ben would go on to make his own contributions to science with his famous lightning experiment and subsequent invention of the lightning rod. In his own unique way, Ben Franklin can be thought of as our country's first cloud chaser. 

You can think of voltage as the "electrical pressure" available from a battery or generator. "Electromotive potential" is the formal technical term. Voltage in a circuit is analogous to water pressure in a hose. High pressure can provide the intense flow for a fire hose, lower pressure for a garden hose.  The higher the voltage, the higher the amount of electrical current, or amperage, that can be produced. 

Amperage (Amps)

Amperage is the unit of measure for electrical current, named for the French scientist André-Marie Ampère to honor his work in magnetism and electricity. The term "milliamp" is a smaller metric unit of the amp. Back to the hose analogy, if the voltage is represented by the water pressure applied, then the amperage is analogous to the volume of water, or current, actually flowing through the hose as a result. 

Resistance and Conductors

Resistance opposes electrical current flow in a conductor such as a metal wire. Resistors can be used to regulate current, similar to valves or kinks in the hose to stick with our hose analogy. Just as there is some unavoidable resistance caused by the surface friction on the water flowing through a hose, no electrical conductor is perfect either. 

Watts 

Watts is the unit of power, the amount of energy a device either produces or consumes. The Scotsman James Watt is recognized by the term for his pioneering work with steam engines since watts measure an amount of work similar to horsepower. 

Watts, or power used in a circuit, are calculated by multiplying voltage times current. Vapers will see variable wattage promoted as a feature of some mods. And that's it for history class. Now that we're familiar with the basic electrical jargon let's get technical. 

Ohm's Law For Vapers (and All Rechargeable Battery Users)

Vaping electronics isn't rocket science, but it is science. Now that we know you're up to speed on battery safety, go on and get out your favorite Velvet Cloud e-juice mod and put on your... thinking vape? (OK, that pun needs a little work.) In the meantime, let's dive in and explain how vapers like us can be responsible, Ohm's Law-Abiding citizens. 

You'll frequently see Ohm's Law expressed in a pie chart as V over I|R. This is the layman's version where "V" is voltage, "I" is current, and "R" is resistance.

"E" or "V" -In electronic texts and popular Ohm's pie charts, you may see the E over I|R version. Either letter makes sense since Voltage is the measure of Electromotive potential.

"I" is considered the logical term for electrical current since it represents the intensity of electricity flowing through the wire. Originally "I" stood for intensität, the German word used by Herr Professor Ohm when he presented his law to the world. Nowadays electrical techs use the term current, or amperage since it is measured in amps.

"R" for resistance is the measure of opposing force to the voltage which regulates the current in a conductor. Vaping coils are rated by their resistance.

closeup of colorful vape cloud made with atomizer no people

Ohm's Law: Doing the Math

One of the easiest Ohm's Law pie charts to understand can be viewed here. (Remember that E or V both represent Voltage.) This is the graphic which Electrician Apprentice Headquarters uses to very literally teach the Ohm's Law rules of thumb. We love it. 

Let's break down the chart into a comprehensible text version, remembering that the vertical line between I and R on the chart is a multiplier. Eventually, these formulas become second nature if you use them enough

  • V=IxR or Voltage = Current x Resistance so Volts= Amps x Ohms. 
  • I=V÷R or Current = Voltage / Resistance so Amps = Volts/Ohms
  • R=V÷I or Resistance = Voltage /Current so Ohms = Volts/Amps

For power (watts) there is literally another pie chart to calculate wattage.

In the electronic world, you'll frequently see the omega symbol Ω to represent ohms. Coils are rated by their resistance in ohms so you'll see something like .6Ω, or 1.0Ω. To keep things simple, let's say you have a 6-volt battery with a maximum 8 amp discharge rate and you want to know how much current is drawn using a 1Ω coil. 

6V ÷ 1Ω = 6 amps

So you're well within the safe discharge range of your 8 amp rated battery. Now let's say a vaping pal puts you onto big voluminous clouds and is raving about the pleasures of sub-ohm vaping with Velvet Cloud 100% VG e-liquids. Can you use a .6Ω coil and jump into sub-ohm vaping with the same battery?

6V ÷ .6Ω = 10 amps. 

Nope! You're 2 amps higher than the maximum discharge rating of that particular 6V battery. How about that same sub-ohm coil with a 4.2V battery and an 8 amp rating?

4.2V ÷ .6Ω = 7 amps

Vape away, you're 1 amp under, well within the 8 amp safety range. But will the battery need to be recharged more frequently? Let's see how much power we're using with the various mod configurations we've been tinkering around with using the Ohm's Law PIE formulas. Once again if we know any 2 of the 3 variables we can always find the third. 

P= I x E or power = current x voltage meaning Watts = Amps x Volts

I = P ÷ E or current = power ÷ voltage meaning Amps = Watts ÷ Volts

E = P ÷ I or voltage = power ÷ current meaning Volts = Watts ÷ Amps

So we have a 6V battery with a 1Ω coil drawing 8 amps. How many watts are we using?

8 amps x 6V = 48 watts

With the .6Ω coil drawing 10 amps?

10 amps x 6V = 60watts. We're into light-bulb power territory. But you can see how Ohm's Law can help prevent hazardous situations before they occur. Knowing the watts used by your e-cig or mod is useful. But, when it comes down to how long a battery will last between charges for vaping throughout the day, we need to dive into the mysterious world of milliamp hours.

mAh Goodness! Watts up with that?

You've likely seen labels such as "1500 mAh" on rechargeable batteries along with the voltage, perhaps 4.8V. Battery capacity is represented most commonly in milliamps per hour or "mAh" with a maximum continuous discharge rating in amps, as we discussed above. Batteries are also classified by the physical size, for example, the popular 18650 which measures 18mm x 65mm with diameter followed by height.

Milliamps per hour are the unit of measure for how much amperage can be delivered between charges. One mAh is 1/1000 of an amp hour so a 1000 mAh battery can deliver 1 Ah (amp hour), a 1500 mAh 1.5 Ah etc. Think of mAh as the fuel tank on a car, and watts as the size of the engine. The larger the tank, or mAh, the longer the battery will last between charges. The higher the watts or the bigger the engine, the faster the fuel gets guzzled. The mAh rating doesn't affect Ohm's Law. For example, a 4.8V 1500mAh can be interchanged with a 4.8V 800 mAh. Of course, now that your an Ohm's Law expert, you've already figured that out. 

Whew! We don't know about you, but the professors here at Velvet Cloud are ready to put our feet up for a nice relaxing post-lecture vape with our favorite high VG e-liquids. If you're still eager to read more about the world of choices in the vaping world check out our recent post about  Nicotine Salts vs Freebase Nicotine.






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