Protected batteries vs IMR - safety

[rolygate]

GK,
You are most likely correct: the safest mod of all is probably, as you say, a Puck-style 4-batt boxmod with either 4x '1.5v' main street rechargeable AA cells for 4.8 - 5v or 3 cells and a dummy cell for 3.6 - 3.8v. Variable voltage as well

As most know, rechargeable AAs are 1.2v in reality, not 1.5v.

But the question the battery section is supposed to address is: which batt in a standard mod is going to be the safest bet. The answer is, the one least likely to blow up in your face no matter what goes wrong. There is only one answer to that question, and for a nominal 3.7v mod it's an li-mn cell (IMR).

However we could add a section with your suggestion because you are exactly right, IMO.

 

[swedishfish]

GK,
You are most likely correct: the safest mod of all is probably, as you say, a Puck-style 4-batt boxmod with either 4x '1.5v' main street rechargeable AA cells for 4.8 - 5v or 3 cells and a dummy cell for 3.6 - 3.8v. Variable voltage as well

As most know, rechargeable AAs are 1.2v in reality, not 1.5v.

But the question the battery section is supposed to address is: which batt in a standard mod is going to be the safest bet. The answer is, the one least likely to blow up in your face no matter what goes wrong. There is only one answer to that question, and for a nominal 3.7v mod it's an li-mn cell (IMR).

However we could add a section with your suggestion because you are exactly right, IMO.

I think I'm more confused now. So the safest battery for a 3.7v mod is protected? IMR?

 

[cement]

The safest mod to vape is a true pass thru , it takes the battery out of the equation!!!

 

[Goldenkobold]

The safest mod to vape is a true pass thru , it takes the battery out of the equation!!!

until you trip on the cord

 

[rolygate]

I think I'm more confused now. So the safest battery for a 3.7v mod is protected? IMR?

No, an Li-Mn (lithium manganese) cell is not protected - because it is a 'safe chemistry' battery: that is, one that vents gas slower when there is a fault. An AW IMR cell is a 3.7v Li-Mn battery.

AW also make an ICR cell, this is a protected Li-ion battery, much like the usual protected Trustfire etc, but believed to be of better quality. Pila is a similar make with a good rep.

The difference between these types of battery is very much like the principal way explosives are categorised:

- The amount of gas produced
- The speed of the gas generation

Just as an explosive that produces a lot of gas, fast, is called a 'high-explosive' because it is a lot more powerful than your plain vanilla gunpowder, a Li-ion cell produces a lot of gas, fast. In fact if you put it in a metal container with no vents it's a grenade. In contrast a Li-Mn cell when shorted out or faulty due to charging issues produces less gas, and slower - so it does not 'explode' in the same way a Li-ion cell can. This is why it's called 'safe chemistry' although these things are relative. If it was placed in a perfectly gas-tight enclosure it might well still explode, though it would be less violent than a Li-ion cell going off.

It will still vent with gas, and catch fire (especially if confined in an ignitable container) due to the heat created and the fact the gas is partly hydrogen - but there is less gas, produced slower, than with a faulty Li-ion cell venting.

If you put some gunpowder loose on the ground and ignite it, it goes up with a whoosh, but without an explosion. It needs to be confined in order that the relatively low amount of gas, produced 'slowly', will cause a bang (an explosion).

If you do the same with a high explosive, such as those used as a detonator, like mercuric fulminate, picric acid, or lead azide, they go with a bang even when unconstrained. This is because they produce a lot of gas, very fast. (I used to work with the stuff.)

This is the basic difference between Li-Mn and Li-ion. You will note that even gunpowder will cause an explosion if confined, and so will an Li-Mn cell most likely, if placed in a strong, gas-tight container - though anyone using a mod with no vent capability is taking an unnecessary risk - drill some holes in it. But an ounce of gunpowder going off is nothing to an ounce of mercuric fulminate going off...

 

[D4rk50ul]

I just did a bunch of research on this because my prior belief was put into question and I had to reconfirm. I'm sticking with IMR ("LMR") batteries for sure. I do think that having a proper fail safe built into your device is half the battle though. I know on the Reo that I use the spring will collapse on the bottom in the event of a short, find out what your mod's fail safe is and make sure its intact.

Like the above post said, I'd rather have a slow controlled gas off than a violent explosion. Also IMR batteries operating tolerances are much less likely to be pushed over the limits than a cobalt based lithium cell when used with a PV IMO. They can handle rapid discharge rates and high current spikes whereas it could trip the protection on a standard LiCo battery or if the protection fails potentially cause a huge hazard. I apply the same logic that works for PSU's when building a computer, or engine dynamics when building a car. The closer to the limits you push something, the more likely it is to fail. If you only push it to 50% of its potential it is going to be much safer and reliable.

Make sure you have a vented battery compartment on your device as its the #1 thing you can do for safety from a malfunctioning battery properly before it builds up and causes an explosion. Make sure you check them for excess heat and store them in cool dry areas. Test them for over charge/discharge regularly with a multimeter as this is the most common way to get a failure. Don't run them in series unless the cell is designed to handle it, regular cobalt based ones are usually not designed for this, only LMR (IMR) and LiFePO4. Use the proper charger for the cell, not all chargers are made to work with LiMn and LiFePO4 batteries and can overcharge them making it a hazard. Ideally we would use LiFePO4 batteries but they seem to only exist in the 3.2v variety for a single cell unless ran in a pack or in series, the 18650 is 3.2v @1200mah.

As far as I can tell the order of safety for batteries is this,

LiFePO4 Example
LiMn2O4 Example
LiCoO2 Protected Example
LiCoO2 Example *DO NOT USE THESE*

Thought this was cool I found it looking through hobby sites at battery comparisons, etc. Fireproof Battery Bag


Remember this is just my opinion and should NOT be used as fact or even a guideline. Do the research yourself and draw your own conclusions!

 

[rolygate]

Some good points there. The only thing I'd debate is the relative position in the 'safety scale' of Li-Mn and Li-FePo4 cells.

We had to debate this initially and came to the conclusion that, although Li-FePo4 cells may be even more stable than Li-Mn ones, for practical reasons Li-Mn batteries are safer in the usage profile that we employ. This is because Li-FePo4 cells have two negatives:

• Some Li-FePo4 cells are of extremely low quality and may be even less capable than some cheap Li-ion batteries. They can have a C rating of just 1C or less. This means an unsuspecting buyer could purchase them thinking they are good-quality batteries. The buyer needs to actively select 'real' Li-FePo4 batteries, which have a rating of 5C to 10C.
• Li-FePo4 cells need a special charger, or, the charger voltage switch needs to be re-set to the lower range, where applicable. This means that there will be occasions where things go wrong and the cell is overcharged. Overcharging is probably one of the main causes a battery fails. Since Li-FePo4 cells are commonly stacked, for 6 volts, this is not good.

So our conclusion was that, although theoretically a Li-FePo4 cell may be better, in practice a good Li-Mn (such as an AW IMR) is a better choice.

 

[SteelJan]

Some good points there. The only thing I'd debate is the relative position in the 'safety scale' of Li-Mn and Li-FePo4 cells.

We had to debate this initially and came to the conclusion that, although Li-FePo4 cells may be even more stable than Li-Mn ones, for practical reasons Li-Mn batteries are safer in the usage profile that we employ. This is because Li-FePo4 cells have two negatives:

• Some Li-FePo4 cells are of extremely low quality and may be even less capable than some cheap Li-ion batteries. They can have a C rating of just 1C or less. This means an unsuspecting buyer could purchase them thinking they are good-quality batteries. The buyer needs to actively select 'real' Li-FePo4 batteries, which have a rating of 5C to 10C.
• Li-FePo4 cells need a special charger, or, the charger voltage switch needs to be re-set to the lower range, where applicable. This means that there will be occasions where things go wrong and the cell is overcharged. Overcharging is probably one of the main causes a battery fails. Since Li-FePo4 cells are commonly stacked, for 6 volts, this is not good.

So our conclusion was that, although theoretically a Li-FePo4 cell may be better, in practice a good Li-Mn (such as an AW IMR) is a better choice.

I would add the caveat that IMR batteries can be a better choice if your mod has short circuit protection built in and was designed to handle the higher amperage of LR at the same time, meaning it's switches, buttons, wiring, etc is rated for the higher amperage.

We cannot simply say that IMR is the safest choice in every mod.

 

[Mudflap]

From batteryuniversity.com

What every battery user should know

A major concern arises if static electricity or a faulty charger has destroyed the battery's protection circuit. Such damage can permanently fuse the solid-state switches in an ON position without the user knowing. A battery with a faulty protection circuit may function normally but does not provide protection against abuse.

Don't put too much faith in your "protected" lithium cobalt batteries. Especially if they have some variation of xxxxFire on the label.

 

[Goldenkobold]

I have had two true device shorts in mods.

I had a mechanical mod short once due to damage on the outer tape of the battery (caused by the threading catching the tape I assume as it was a tight fit). The metal on metal on the tube wall closed the circuit and as soon as I installed the cartomizer it fired, this is one instance where I am very glad I was not using an IMR battery. The thought of my house catching on fire is no more appealing to me than an explosion in my face. It caused no damage to the protected battery or device...obviously the battery was tossed anyway as its torn wrapper made it less than safe...its possible the spring would have melted if I was using an IMR its also possible I wouldn't have noticed and it would have burnt my house down and started a raging inferno the likes of which we have not seen since the great fire in New Orleans in 1788. By now most of us who care have seen the Photo's of the IMR in the coat pocket that caught fire....imagining the left unattended on my work bench or dining room table with paper strewn around and you have a recipe for something worse than broken teeth (though honestly either of the two fit my definition of catastrophic failure).


The second was just me building a bad DIY mod and I let the led connection wonder too close to the wrong wire, this one was noticed right away, the LED came on briefly, and I doubt it mattered what I was using battery wise as I fixed it before assembling anything.

If someone was to ask me what the safest non stacked battery to use in an all metal mechanical mod that they purchased (as opposed to building around a Nimh block) I would not say an AW IMR but an AW protected Li-ion. However I think the built in protection on a Provari or similar units probably makes it a safe choice, but the MOD has to account for the lack of protection.

 

[D4rk50ul]

You are right in the way that we use batteries I would put IMR batteries at the top of the list IMO, but I was just saying the safety order based on the chemistry of the battery. The amount of energy released from a failure is directly related to the size of the battery capacity so a 5000mah battery would be your worst nightmare in the case of failure. Protection circuits are great but they can fail too, and more often in cheaper batteries which unfortunately is a category a lot of the commonly used batteries fall into. I've been reading a bunch on the topic because frankly I want to keep my face intact for the foreseeable future. If I interpreted all the data I read correctly the safer chemistry batteries if they are in fact what they claim to be (see cheap batteries) then they are very highly resistant to thermal runaway. They also can support a much higher discharge rate and load rate than a Cobalt based battery which means that if your device pulls a ton of juice from it, it won't be overtaxing the cell. What they DO lack is overcharge and overdischarge protection which usually at worst will ruin the cell if you overcharge it or run it dead (overcharging with a faulty charger above 4.5v can cause a failure in the cell (see fire and explosions). This is why a charger like the Pila IBC should be used and the cells should be tested regularly to ensure this isn't happening. Also don't vape your batteries dead as no Lithium based battery is safe this way. Here are some nice reads, with plenty more out there.

Lithium Battery Failures

This one is interesting in that its testing the point at which "protection" trips on the battery. IMR's are obviously designed to handle much higher loads than a standard LiCo battery but its still relevant to the PV world.

Test of overload trip current in 18650 batteries | BudgetLightForum.com

Cool tests of batteries that some here use.

Reference: mitro's pile of battery graphs | BudgetLightForum.com

Batteries being over discharged and the protection not working apparently.

Is this thing gonna blow up in my pocket? | BudgetLightForum.com

When protection goes bad.

Trustfire X6 SST-90 EXPLODED | BudgetLightForum.com

Also a good read...

New section added 12/27/11: Li Ion beginner primer

Another one

http://libattery.ustc.edu.cn/english/introduction%203.htm

I'm not trying to start another which battery is better war everyone is entitled to their own opinion. I will stick with IMR batteries due to what I believe is superior tolerances especially considering the application we are using them for, and I will make sure ALL my devices have a fail safe AND ventilation for the battery compartment. There is always a risk that you will get a bad cell and you need to be prepared. Like I said before everyone should read and come up with their own opinions and not just take mine or someone elses word on it.

 

[SteelJan]

Good reading materials there J808. One of them, the Trustfire X6 link, discusses a failure where there were stacked batteries, lots more good data points we vapers need to remember there.

In at least one of my youtube modding videos, I show for my two-battery mods, I keep the same sets of batteries together. I buy them together, number them in pairs, always charge them together and always use them together in the same mods. It's the best way I know of to hope each one holds the same charge, drains at the same discharge rate, etc. When one of them shows any damaging on the package or every couple of months, whichever comes first, the pair gets tossed... meaning I take them to Best Buy for their lithium battery recycling bin.

You know, something I'm not good about is storing them. After reading through your links, I'm now thinking about that. I recharge them outside on an aluminum pan in the shade. But then I bring them in and put them in an open plastic container on the shelf in my den. I definitely need to rethink that. One of the guys in your links said he stores his in his refrigerator? Hum.... What are you guys doing for storage?

 

[Switched]

I use the appropriate battery cases. They are cheap and just store them on my desk.

In all honesty more important than what we use, if folks are going to go away from commercial PVs, they need to educat6e themselves wrt the cells they will be using etc... I bet only about 2% of vapers actually research batteries let alone batt chemistry etc... Yet they research acetyl in liquids and send off alarms left right and centre. Cooks using butter to cook foods on a daily basis are exposed 100 times more than someone vaping the odd caramel. The acetyl reports came from factory workers exposed to HIGH concentrations of acetyl and one other product for years, which caused a revision in air filtration systems etc...

That anecdote was to demonstrate where folks concentrate on... Some of these panic attacks are ridiculous compared to the harm they did while smoking. I am not trying to condemn concerns, just folks need to read properly. Half of what we eat, and use daily can kill us.

 

[rolygate]

Looks like the worst mod explosion ever has just happened.

http://www.e-cigarette-forum.com/fo...ussion-exploding-batteries-4.html#post5038291

http://www.e-cigarette-forum.com/fo...ussion-exploding-batteries-4.html#post5073116

Apparently the guy was in intensive care, with a breathing tube. His face got mashed. This was a Puresmoker V3 with two Tenergy Li-FePo4 batts that blew almost as soon as he hit the switch (according to the report). Teeth knocked out, driptip embedded in the face.

So like I say, if you have a metal tube mod, make sure there are good gas vents and maybe also a blowout plug at the bottom end. The top cap blowing off first is a bad idea. Don't use low-quality Li-FePo4 cells with a rating of 1C or whatever those Tenergy ones are. Real Li-FePo4's have a 4C to 10C rating.

When I started banging on about all this there were many who said I didn't know what I was talking about. After 40 years in engineering, including gunmaking and battery systems, sorry but I do. The proof is lying in a hospital bed.

 

[Traver]

To me it seems to boil down to the quality of the circuits in the pv, the battery, the quality of the battery itself and the quality of the charger. I use AW IMR batteries wherever I can. The bigger problem for me is trying to figure out the quality of the pv's and finding a safe charger.

 

[Goldenkobold]

What is the failure mechanics on a Li-fepo4? It seems that on this post there was no warning or venting (the V3 does have a few vent holes in the bottom) just a big boom.

 

[D4rk50ul]

This is a good place to start Lithium Secondary - Rechargeable - Cells but I still don't use batteries in series or LiFePO4 batteries because I just don't trust it even though they are said to be the safest type. As was said before they may not be ideal for the application we use them in which makes their inherit safety irrelevant.

I think all tube mods should have a press fitted bottom cap with breakaway mechanism to allow for it to be the weak point in case of pressure build up. You also need to consider how hot it can get in a metal tube when left in direct sunlight, or even bright artificial light. I haven't done any testing yet but I assume you would see a huge increase inside a SS tube when outside versus the ambient air temperature. Also ventilation is key but its not fool proof as pieces of the battery casing could block it in the event of a failure and cause the remaining pressure to build up inside. There should be awareness about the dangerous with any high power batteries but without absolute panic as failure rate is almost 0.

Don't buy cheap batteries and chargers. If you can afford a $100-$300 mod you can afford a pair of high end batteries. Treat them with respect and know what the limitations are of the battery you are using. Test them regularly with a voltage meter and dispose of them the instant they start performing below their manufacturers specifications. Use the correct charger for the battery type you are using, not all chargers work on all the variants of Lithium batteries. Store them in a safe place.

It is at the point of picking your poison because there isn't a battery that is perfect for vaping in all devices. It is up to the maker of the device to ensure that the battery used isn't being abused by the mod and that proper safety checks are in place. You wouldn't want to use an IMR in a low drain mod with no safety mechanism or ventilation, just as you wouldn't want to use a protected LiCO battery in a mod pulling more than the recommended amperage from the battery and potentially causing a failure.

It's possible the ideal battery will be a Lithium (NCM) Nickel Cobalt Manganese - Li(NiCoMn)O2 with a PCM installed but the only problem is most Protection circuit modules are not designed to allow over 3.7v and over 2a draw which the IMR is more than capable of doing on a regular basis. It would constantly trip the circuit and I'm assuming this is why we haven't seen protected ones yet. This is the closest I could find for a compatible PCMTenergy 32002 Protection Circuit Module (PCB) Round for 3.7V Li-Polymer Battery 3.5A Working (6A cut-off).

I think the ideal thing here is to remember that as an advanced user of a mod you should be as safe and educated as possible. Also steer away new users from these potential problems until they themselves feel that they are capable of handling them in a responsible manner. There is a reason 300mah and under batteries are used in commercial e-cigs, they pose a very small safety risk because of the low stored energy.

 

[Switched]

A thermal runaway will occur rapidly, however from runaway to total catastrophic failure takes more than mere seconds. I have had 2, and both were averted with quick thinking as I knew what was happening, with quality batteries.

 

[the mechanic]

So what you ars saying is that a totaly sealed mod could be dangerous such as my silver bullet. Should i drill holes in it.My omega has holes in it and i think they are made by the same company.---Please reply

 

[D4rk50ul]

So what you ars saying is that a totaly sealed mod could be dangerous such as my silver bullet. Should i drill holes in it.My omega has holes in it and i think they are made by the same company.---Please reply

I won't knock the SB but I would want some way for the gas to get out so pressure doesn't build up.

Sent from my HD2 using Tapatalk