Battery Technology

[ChillerVapes]

I received this in a news letter from the original supplier that shan't be named:

Battery Technology

As someone relatively new to the world of vaping, not quite a year into it, I’m sometimes surprised by the combination of opinion and understanding that people exhibit when posting on web forums about electric circuits. In an ideal world, opinion is outweighed by understanding, but I often read posts where the ratio is reversed by a huge margin. We were very fortunate a short while ago when a customer of his own volition tested a number of batteries of different technology on different atomizers whilst logging the voltage. I learnt a lot from his results, the biggest thing being that the batteries performed according to well-known 18th and 19th century electrical theories, and were completely oblivious to opinion. My heroes Charles-Augustin, Georg, Allessandro, Michael, and of course the two James’s remain firmly on their pedestals. Skip to the last paragraph if you don’t like things too techy…

Let’s start with the two main types of battery used in electronic cigarettes. It was rare to see anything other than ICR batteries (generally just known as Lithium ion) in the e-cig world until earlier this year, and then people started talking about IMR batteries. Lots of claims have been made about IMR, and there has been some really dodgy maths published to show some remarkable virtues that defy the laws of Physics. The reality is that IMR has some clear advantages in some circumstances, but in others ICR technology is the clear winner. Both types of battery use Lithium ions as the charge carrier, and chemically the major difference is the anode material. One uses Lithium Cobalt Oxide, the other uses Lithium Manganese Oxide. They (evidently) differ radically in internal structure, but with both it’s a really bad idea to take a look inside, as metallic Lithium is pretty volatile and better off in the battery than exposed to the atmosphere. They both have a nominal voltage output in the region of 3.7 V, a peak voltage output 4.2 V, and within limits behave in a very similar way. Understanding how they behave outside those limits needs a little electrical theory.

The primary quantities of interest in DC electric circuit theory are potential difference (generally referred to as voltage - V), resistance - R, current - I and power - P. The voltage (potential difference) of a battery is a measure of its ability to push electricity round a circuit, much like pressure in a fluid. The more of it there is, the faster the electric charge carriers move. The current in a circuit is a product of how many charge carriers are moving and how quickly they are moving, and so is akin to the rate of flow of a fluid. The resistance of a component in a circuit is a measure of how much current is produced for a given potential difference (or voltage). This is one of Georg’s (Mr. Ohm), and can be written as V = I x R. So a 2.4 ohm atomizer on a fully charged (4.2 V) battery will give a current of 1.75 amperes – and this current will be supplied regardless of the battery technology. If you think you can detect a difference, your senses are deceiving you. There isn’t one. The batteries will both quickly drop to around the nominal voltage of 3.7 V, and for the bulk of the time of use the current will be around 1.5 A.

The first difference of note is how long the batteries will last before needing a recharge. Battery capacity is generally measured by the milliamp hour (mAh), and in the 14500 battery range ICR batteries typically have a nominal capacity of 900 mAh; IMR typically 650 mAh, substantially lower. I find the milliamp hour an annoying unit, as it does grave disservice to the memory of Charles-Augustin, but it’s what the industry uses. 900 mAh means the battery can provide 900 milliamps (0.9 A) for an hour, or 450 mA for two hours, or 1.8 A for 30 minutes, and so on. Using the 2.4 ohm atomizer above, an ICR battery can be expected to last just over 35 minutes of button pressed time, and an IMR battery just over 25 minutes. For me that’s the difference between getting a full day at work from a single charge and finding myself in nicotine withdrawal at about 4.00 pm – never that funny at the time.

The next thing to consider is power, the rate at which energy is transferred, heat generated, and liquid vaporized. Many people use the relationship between voltage and current to calculate power: P = I x V. A few use a substitution to make the relationship into P = I2 x R. This can lead a keen amateur astray, it looks like increasing the resistance will increase the power output, but it doesn’t. As the resistance is increased, the current goes down, so it’s much better to use the relationship P = V2 / R. This correctly tells us that as we reduce the resistance of the atomizer for a given vaping voltage, we get an increase in power. Most vapers are familiar with this effect; low resistance for more vapour.

Whilst we have established that in terms of battery life ICR can outperform IMR technology for a given battery size, the reverse is true in terms of power. This is due to the ability of the battery to pass a high current, with some IMR batteries capable of peak currents almost 10 times that of a similarly packaged ICR battery. We established that a 14500 ICR battery is a good choice for a 2.4 ohm atomizer. However most ICR batteries can only reliably supply a current of 2.0 A, limiting them to about 1.8 ohms as the minimum atomizer resistance. This equates to a power of about 8 watts. Many 14500 IMR batteries will happily drive a load resistance of 1.0 ohm or lower, and are capable of delivering over 20 watts peak. With a 1.5 ohm atomizer they deliver power at 9 – 10.5 watts, but only have a life of about 16 minutes of button pressed time between charges.

For those that skipped the middle bit, this is the last paragraph. If you are using atomizers with resistance over 1.8 ohms, ICR batteries, such as the white TW 14500 supplied in the Odyssey kit will offer the best performance. If you use atomizers under 1.5 ohms more current is required, and there is likely to be a benefit from using IMR technology unless the ICR battery is well over 1000 mAh. If you use a DCC/DCT on a 14500 mod, IMR technology is definitely worth trying, and you will soon be able to try this ******* ****** products.

Liam Humberstone

Product Engineer

It sounds interesting but I don't get it. LOL

[Chrissie]

I don't get it all either Chiller - partly due to the fact I fell asleep half way through reading it

[alvoram]

He's basically saying a milliamp is a milliamp, no matter whether you use IMR or ICR, a battery that has a rating of 2000mah can run 2 amps for an hour. An IMR can supply a much higher current, but the rules still apply, and a 2000mah battery supplying a higher current wont last as long as one supplying a lower current. I think that's what he's trying to say.

I'm not sure what he is getting at though, because most of us now require that higher current, with our VV and VW devices, 2 amps is not enough.

[suede]

What ???

[blakey]

What he fails to factor in to his equasions is variable voltage devices that draw a lot of power very quickly via their boost circuits need an imr battery because the ICR will not be able to have enough current drawn from it.

[ChillerVapes]

So, would a ICR battery die faster than a lower mah IMR if used in a vv device at a higher voltage than 3.7v?
Eg: 800mah ICR vs 700mah IMR at 4.1v on a 1.8ohm atty

[blakey]

Yes, because once the ICR fell below the required 3.7v then it would need recharging.
The imr will allow the vv boost circuits to draw high current when the battery falls below 3.7v

[maccafan]

It is true that if you use a Odyssey with a 2.2- 2.4 ohm single coil carto, the 14500 ICR will last you longer. It'll last you even longer with a 3.0 ohm carto and longer still with a 4 ohm carto..You'll get a crap vape but the battery will last.

That's what those wall of words mean.

[Bluefish]

So you mean if you draw less power, the battery will last longer? well i never

[Moon]

Can any of the battery gurus tell me this please...

I've just ordered a Sirius mod after seeing Romastino's YT review, which has a mechanical switch.

The vendor is saying to use protected batteries, but wasn't sure whether IMR would be ok, as he doesn't know much about them.

I use IMR (Senybors) in my Bolt as they were recommended by Torchy when I told him what I was using them for, although I know that has a wired switch if that makes a difference.

That's the background, so my question is under what circumstances would protected batteries be required, rather than IMR, as I'm struggling to see the difference between using the IMRs in my Bolt and using them in the Sirius, unless it is the wired/mechanical switch difference.

Alternatively, the vendor might be just covering his arse, which is fair enough of course.


Can somebody please advise this simpleton, and I'll promise not to sue you should I happen to blow my hand or face off should you recommend that the IMRs will suffice.

[blakey]

Imr's will work fine in that mod just the same as in the bolt but imr's have no circuit protection, a protected battery would be a more sensible option in a mod that has no built in protection.

[maccafan]

Usually the use of protected batteries is what anyone would recommended in a unprotected mechanical mod..

IMR's are safer chemistry and are not as volatile in failure..There is no difference between the BOLT and the SIRIUS except one uses wire to carry some current part of the way..So if you are comfortable using a IMR on the BOLT you should be fine..

What I would advise is buy some copper springs and fit them to both mods..They will collapse in the event of battery failure offering you some amount of protection..

[Moon]

Cheers gents.

What would cause the batteries to blow up? I'm assuming it's a short circuit, but short circuit in what?

Macca, the Sirius has a copper spring and the vendor has said that he has tried shorting the mod and it collapsed, but I'll maybe get one for the Bolt just in case.


Ultimately, are you both telling me to buy some protected batteries?

[maccafan]

The switch could short. The connector could short..Your atty could short. The battery could short internally and protection circuit failure can also cause a battery to fail.

Then it gets very hot and unloads all at once and catches fire when it goes thermal. There is a instantaneous build up of venting gases and if there is no escape or insufficient escape, the pressure gets too much with undesirable consequences..

What you want to use depends on how safe you feel and also what resistance you normally use and if a protected ICR can supply that load..Good ICR's in 18650 size usually can like the protected AW 18650. Samller ICR's may struggle.

Sometimes using an IMR is safer simply because you are not stressing the battery out that much under load.

[blakey]

Protected batteries prefferably, saying that though I use imr's in just about everything but I do make sure I have a collapsable spring in a mechanical mod. If your attie acquires a short it will attempt to draw a very large amount of power from your battery, the battery will overheat and its that heat that collapses the spring, no spring and the battery just keeps heating up till the switch is released or the attie is removed.