Mechanical Mod Safety and Proper Usage Guide
This article is intended for new vapers who want to get hold of their first mechanical mod. The first thing we must distinguish is the difference between a mechanical mod and an electronic cigarette a.k.a Personal Vaporizer (electronic PV).
A good and properly designed electronic PV has a built-in chip in the unit itself that acts as a protection circuit; it prevents things we want to avoid while using any unit and these usually include over-discharge and short circuit.
Because of the built-in safety features, electronic PVs are inherently safer than fully mechanical mods. Some popular electronic PVs are Provaris, Vamos, EVICs, E-Gos and iTastes.
The problem with a mechanical mod, however, is that obviously it does not have a chip that can monitor things like short circuit and over-discharge. Short circuit and over-discharge, without getting too technical, basically make the battery unstable to a point that it may overheat and catch flames or worse.
And this is the reason why we are posting this article – so that we can show you what you can do to compensate for the mechanical mod’s lack of native circuit protection.
We have compiled a list of things to remember when dealing with mechanical mods.
For some of these, it is implied that you get yourself a multi-meter. In fact, if you choose to own a mechanical mod, you should also get a decent multi-meter.
Let us go into each in detail.
We have compiled a list of things to remember when dealing with mechanical mods.
Regularly check for atomizer resistance and short circuits
Unlike your Provari or Vamo etc., a fully mechanical mod will still fire even when a short occurs on the atomizer. A short-circuit technically means zero or close to zero resistance (ohms), but most electronic PVs won’t allow anything lower than 1.2/5ohms. This is to ensure the batteries are not stressed especially if they have lower C ratings.
If you are using a new atomizer, make sure you check your resistance first before screwing it on your mechanical mods.
If you are using a rebuildable atomizer, do not let the ohms go too low as some batteries may become very stressed with lower resistance. When starting out, build them at a standard resistance around 2.0-2.5. ohms just to be safe.
Shorts don’t always occur in the atomizer, test the unit itself as well. To do this with a multi-meter, take out your battery, with one probe touch the positive pin of the mod and another on the body. If the meter shows any kind of resistance, it means a current is flowing and you have a short somewhere. Immediately remove the battery and locate and cure the problem.
When testing for resistance using a multi-meter, note that the multi-meter also carries its own resistance or lead resistance.
In cheaper multi-meters, we have seen this lead resistance go as high as 0.6ohms. Touching both probes together will usually display how much lead resistance the meter has. Subtract this from what is displayed on the meter when testing your atomizers to get the atomizer’s real resistance.
So if your atomizer reads 2.0ohms, it may actually be just 1.4ohms if your lead resistance is 0.6ohms.
Use A Safety Fuse
There are several safety fuses available for mechanical mods. These are designed to break the circuit in the mod if the battery gets too hot. There are electrical circuit fuses, like the ‘Vape Safe’ fuse. These work in the same way as the protection circuit does on some batteries. They add an extra couple of mm to the length of the battery.
Another type of fuse is a ‘hot spring’ Every mod uses a spring in the endcap to maintain good electrical contact between the battery and the mod. A hot spring does the same thing, but when it gets hot, it melts which breaks the electrical circuit in the event of a battery going bad.
If a fuse trips it will need to be replaced, ideally along with the battery that caused the failure as well. While fuses do not make your mechanical mod entirely safe they do provide an extra layer of protection.
Do not use the battery when it is fully discharged
Another suspected cause of batteries being damaged or even catching fire (thermal runaway) is when it continues to discharge way past its discharge threshold. Meaning; using it way past empty.
A Li-ion battery typically holds a capacity of 4.2 volts at 100% charge. As the battery is used, this voltage drops.Depending on quality and manufacturer, typically your batteries can be safely used until the voltage drops to between 3.6 and 3.3 volts (or even lower on really superb ones).
On the safe side, when a battery reaches 3.6 volts, just assume it is empty (as it might as well be), stop using the battery and recharge it as soon as possible. Li-ion batteries will enjoy a longer lifespan if partial discharge is practised.
If you are unfamiliar with your batteries, use your meter to test your batteries often to determine how much usage time you typically need to get from 4.2 to 3.6 volts. This will help you estimate how much is left when you don’t have your meter with you.
Just note that as the battery ages, the time to reach empty will decrease, and this is due to the internal resistance building up (We will talk about how to determine this in another article about internal resistance).
Avoid stacking batteries
Unless you really know what you are doing, simply do not do it.
Stacking batteries means putting one battery on top of another in series, so they produce a higher voltage. This also adds much more stress to each of the batteries. Two “stacking” batteries is not recommended
Not all batteries are designed to be stacked. Stacking will stress both batteries much more than when the same atomizer is used in a single-cell configuration.
Both your batteries must be capable of very high C ratings (which we may discuss in another article) and unfortunately most batteries are not. If you really want to stack batteries, make sure your batteries are designed to do so.
Another problem with stacking batteries is differing discharge rates. One battery may already be fully charged while the other less so. Sooner or later, one will ultimately over-discharge and cause problems.
Even on a new pair of batteries, there is a chance that in time one of these batteries “gets old quicker” which will make it empty quicker than the other. This often happens even in “manufacturer pairs”.
If you have no choice, such as you have a mechanical mod that only accepts stacked batteries, you can use a spacer (dummy battery) or purchase the best quality batteries that are designed to be stacked. Use atomizers with a resistance that will not stress your setup. And always check the health of your batteries regularly, both while in the device and in the charger
If you really need a higher voltage than what a single cell can give, consider a variable voltage electronic PV or a kick device for your mechanical mod.
Prevent your mechanical mod from firing accidentally
Other than discharging your unit beyond recommended levels, another cause of over-discharge and battery stress is accidentally firing your unit for prolonged periods of time. Usually this happens accidentally.
Electronic PVs like the Provari, Vamo, E-vic and eGo, usually have an automatic 10-15 second cut-off to prevent this, as well as manual “off” mechanisms where you can turn the units completely off.
Some mechanical mods may have lockable firing mechanisms that function as an “off” mechanism. But not all do.
If your mechanical mod has this feature, use it whenever you store your mods in your bag or even in its case. This will prevent it from firing.
If your unit does not, then make sure to remove the atomizer and ensure nothing can short the positive terminal (the pin where your atomizer connects to). Placing your unit in a small pouch/bag before placing it in your case, can help prevent this.
Use only protected batteries or better still, use safer chemistry batteries
In our market today, there are many kinds of batteries that can be used in a mechanical mod.
Two of the most popular battery types used in mods are ICR (LiCo02) and IMR (LiMn) / IMR hybrids. Both of these are lithium-ion (Li-ion) batteries.
In terms of safety the difference between the two (ICR and IMR) is the chemical composition in these batteries. ICR can catch fire at a faster rate than IMRs because they are simply more combustible. ICR are also generally known to stress more easily than IMR. There are two types of ICR batteries, protected and unprotected. Never use unprotected ICR in any mechanical mod as it does not have any safety mechanism in them.
Protected ICR batteries have a basic layer of protection that prevents your batteries from shorts and over discharge problems. Protected ICR with a C rating of 2 amps or more can be used in mechanical mods.
IMRs however, has a more stable chemistry, and won’t likely to catch fire or explode as easily as an ICR can. They do not require protection, and often sold without it. These are also suitable for mechanical mods.
You may ask, what is better an IMR battery or a protected ICR battery?
The general consensus within in the vaping community is that if in doubt, IMR is better for mechanical mods. The reasoning is, although IMR has no protection circuit, by nature of their chemical composition, they are safer than ICR with a protection circuit. Protected ICR batteries have a history of their protection system failing, especially with the cheaper ones. In fact, we have read more incidents of cheaper protected ICR batteries venting flames than IMRs.
An analogy to this is that a protected ICR is like a gun with the safety switch turned on, and an IMR is a gun someone filled with rubber bullets. Both guns can hurt but one is more hazardous.
Do not invert batteries
The outside, or case of the battery is always negative and therefore your mod’s case should also be negative.
In most mods, the negative portion of your battery is at the bottom of the mod to make the entire tube negative.
The reason for this is that if your battery case gets damaged, and it touches the metal tube, your tube will be negative no matter how you positioned your battery. No short will occur.
However, if your tube is positive, and your battery case gets damaged, you will have a short and a serious problem.
Do not over-charge your batteries
Whenever you have fully charged your batteries, before you place them in your mechanical mod, use your multi-meter to check the voltage.
It typically should not go beyond 4.2 volts, although many brands have a +/- .05v in their specifications allowing them to go up to 4.25volts.
If it goes beyond what is specified, consider changing the battery, the charger or both. An over charged battery should be considered unstable and therefore potentially dangerous.
To prolong battery life, charge your batteries at 4.1volts rather than fully charging them.
Also, never try to recharge a battery that has been severely discharged. A severely discharged battery may develop an internal short.
Make sure your mechanical mods have sufficiently sized and number of vent holes
If you follow the rules already mentioned, you should be fine.
But even the most vigilant of us can and do make mistakes. Even if we follow all the rules, there are just some things we cannot avoid such as accidents.
When this happens, it is good to have a unit with some sort of safety mechanism in place. To this end we would advocate the use of a ‘kick’ style fuse in the battery compartment. There are two types; the first is a ‘single event’ type which will require replacement should it blow and a re-settable type with a set number of cycles. Both cut out when detecting an abnormal rise in battery temperature therefore preventing you from operating the device. For £2.50 and £15 respectively, either is considered a worthwhile investment.
One of the biggest problems with a battery experiencing thermal runaway (which may be caused by shorts, stress or over-discharge) is that things inside the battery expand at a rapid rate.
A mod without vent holes is a sealed container that may crack, shatter, or explode causing harm to you and others simply because the pressure inside the mod has nowhere to go.
A mechanical mod with suitable vent holes can prevent this pressure from building up and it can release the rapidly expanding gases before they build to dangerous levels.
Think of a mod without vent holes as a balloon, when you inflate it too far, eventually it will explode. Known within the battery industry as ‘venting with flame’ or ‘rapid disassembly!!!
A balloon with large enough holes however, will just release the pressure no matter how much you blow into it.
Having covered the fundamentals, this may feel like a lot to take in. Eventually these will be second nature to you. So have a great day and enjoy your mechanical mod!!!
Our gratitude goes to Diana and Uba at BumbleVape for permission to use this article. There may be changes including additions and removal of information as it becomes available or irrelevant.
Thank you to VaperCaper for information on Safety Fuses.