Battery testing - choices for series circuits

[RRoberts]

May I ask for a re-cap here?
Any two of the same 4 batteries mentioned above should fit in a single 18650 slot PV (to change the voltage)?
-as long as it has sufficient wiring, switch, etc. I would think is a given.
Ari is going to produce safe combinations w/ volt ratings of these combos among many other things I'm sure. Nice!
Series = stacking, to change the volts to match what carto/atty you want to run.
Parallel = ex. 'my box mod runs two 14500s.'
Are all (or any) of these statements true?
Sounds like my old single 18650 mod will soon see new life.
If this post needs to be in a different thread, just delete (or I can)... PM me. Thanks.

 

[AriM]

May I ask for a re-cap here?
Any two of the same 4 batteries mentioned above should fit in a single 18650 slot PV (to change the voltage)?
-as long as it has sufficient wiring, switch, etc. I would think is a given.
Ari is going to produce safe combinations w/ volt ratings of these combos among many other things I'm sure. Nice!
Series = stacking, to change the volts to match what carto/atty you want to run.
Parallel = ex. 'my box mod runs two 14500s.'
Are all (or any) of these statements true?
Sounds like my old single 18650 mod will soon see new life.
If this post needs to be in a different thread, just delete (or I can)... PM me. Thanks.

All of the above are true and accurate, except for the comment about parallel cells and me producing safe combinations solo...unless I misunderstood it is a community effort, which is not based on my testing

In a parallel config, each cell gets an independent set of leads to the load, so the voltage is the same as with one cell, but the capacity and current availability are doubled for each cell run in parallel....

example:

2 3.2 v 500 mah cells in series = roughly 6.4 volts with a capacity of 500mah and a current capacity up to 1.5 times the original C rating of just one cell

2 3.2 v 500 mah cells in a parallel config = roughly 3.2 volts with a capacity of 1000mah and a current capacity of greater than 2 times the C rating of just one cell

Most box mods still run 2 cell configs in series.....

 

[rolygate]

May I ask for a re-cap here?
Any two of the same 4 batteries mentioned above should fit in a single 18650 slot PV (to change the voltage)?

Basically, yes. We need to come up with safe suggestions for 2 x 3v and 2 x 3.7v in a tube mod where the single cell would be an 18650. An ECF safe solution for 6v and 7v vaping in a metal tube mod. These mods have a history of incidents, and that seems to be increasing, not slowing down. It is partly down to the batteries used, and partly that some of those mods are sealed.

Parallel = ex. 'my box mod runs two 14500s.'

As Ari says, boxmods still run a series config (normally), even though the cells are side by side. If you look at the metal strips connecting them in the box, they are pos to neg between the two cells, not pos to pos. Boxmods often use a simple battery box for AA cells, and these are 'pre-wired' for a series config to give 3v with two 1.5v AA cells.

Sounds like my old single 18650 mod will soon see new life.

No doubt. But please keep in mind that these mods can explode if sealed. Ideally you have a nearby machine shop that can put 3 off, 50mm x 4mm slots in the tube body. If not, then drill a series of holes of at least 1/4" along the body, on two sides. It takes a battery failure plus a sealed tube to create an incident, so if you fix both sides of the equation then you are far safer.

If you are lucky there will be space in the tube for you to slip in some mylar sheet cut to act as a sleeve. This insulates the batteries from the metal tube body. Because there have been a very large number of battery meltdowns and fails in metal tube mods (often leading to just a meltdown not an explosion), but a substantial number less in boxmods, it leads us to think that shorts to the casing may be a factor. An insulating sleeve protects against this. It's why some people tape their batteries.

A mylar sleeve needs perforating to line up with the vent holes.

-------------
mylar info:
grafixplastics.com/mat_thick.asp

Mylar sheet custom cut, 0.020" thick:
electricalinsulationmaterial.com/mylar.html

thin sheet:
amazon.co.uk/A4-Size-Blank-Mylar-Sheets/dp/B004VR2NW6

 

[Rocketman]

Is it possible you are going out on a quest for a bucket of unobtainium?
Is there a safe small cell combination (35mm length cells) that would allow a vaper to
vape a LR atty/carto at 6 volts (or more)? I see many comments about vaping 1.5 ohms @ 6 volts.
People brag about their Brand X stacked battery mod being able to be turned all the way up to X volts before it cuts out. We like to crank things up until they almost fail (or is that just an American thing?)

People seem to get confused when you mention ohms. Some don't know what resistance carto they ordered, much less what they received. A safe small cell stack for 6 volt unregulated high resistance vaping might be possible.
But the same stack might not be safe at a different load level. Mod shoppers can't get a handle on 'C' ratings, can't run an ohms law calculator, don't know how to measure ohms.
They come to ECF to ask "will these batteries FIT". and we answer.

Maybe a caution about severe vaping applications using itty bitty stacked cells.
Is there a reasonable safe limit to what you can get out of these?


Have you noticed that 25mm length Li-ion cells are showing up on suppliers sites?
Are we looking for even smaller mods for high voltage vaping? Stacked batteries in place of 50mm length cells?


Your Mylar idea is a must. I use plastic playing cards, Automotive gasket material, 10 Euro notes ,
even in anodized mods.

 

[rolygate]

I guess 'safety' is really an unobtainable ideal, especially if you are going to run two batteries in series in a metal tube. But it seems reasonable to me that there is a solution that goes some way toward making things a lot better than they are now.

Right now, tubes are blowing up. So if we put big gas vent slots in them and tell people what batteries to use, instead of them putting two unprotected Li-ion cells or two el cheapo whatevers, then immediately there is going to be an improvement in safety.

As regards perfectly safe, or safe even if you do crazy things - well, no, that isn't possible. But you can get them out of that situation with a burnt hand instead of a missing face. Safety is relative, skydiving isn't safe no matter what precautions you take, you are jumping out of a plane. Vaping on 2 batts in a metal tube isn't safe, no matter what precautions you take, because you are holding a pipe bomb. But it can be made safe enough that it doesn't blow your face off, it just burns you a bit. That is the goal of ECF in this. You cannot make people perfectly safe as that isn't possible, their decisions make them safe or unsafe. It is good enough to protect them from unavoidable factors like counterfeit batteries, or faulty chargers, by giving them the best batteries and the best mod design. For stupid, there is no cure. Even there, though, we can aim to try and get them out of it with a burnt hand instead of a missing face.

 

[Rocketman]

Roly,
I agree with your objectives.

 

[rolygate]

Thanks.

It's very, very hard to achieve goals like this because there is a tremendous amount of resistance. But if you look at the future, this is what you see:

- Someone has a blowup and loses an eye.

- Another blowup happens and it is to the daughter of a Senator. He goes apeshat.

- Someone else has a blowup, gets facial damage, they sue the A. off a vendor and name ECF too because this is where they found the vendor.

- The press gets a hold of all this and it makes the front page.

- Some States ban all e-cigs even when they were OK with them before.

- Several States starting with Utah ban mods and make it a criminal offense to be in possession of one in public.

- A couple of countries ban e-cigs totally because they are 'killing people in the US'.

- Things go downhill all round all because vapers refused to stop doing something that is obviously dangerous and will obviously have consequences far beyond their own front door.


That is what I can see happening. Some of it is inevitable if things stay as they are.

 

[AriM]

If you look on page 2 you will see safe recommendations listed. These aren't conjecture. They are based on over 6 months of real research on my part. Including scientific qualification in a lab environment. They aren't guesses. If people choose to ignore them, then that is taking safety into their own hands. If the forum (as a community) chooses not to follow the research (not just mine, but others as well), so be it. I will be including ALL of the research on my ecommerce site. So I have no fear of selling anything unsafe to the general public. I think other re-sellers/vendors should man up and take the same level of responsibility and concern for their customers safety (big kudos to those vendors that do).

It's not a matter of if....it's a matter of when...

"you don't know what you've got till it's gone".....

 

[rolygate]

Let's start with 3v cells for 6v vaping, then.

These have been nominated as candidates for discussion or testing:

Tenergy Li-FePo4 rcr123a 3.2v
AW Li-FePo4 r123a 3.2v

Any more?

Where could you buy these with a reasonable expectation they are not counterfeit?

 

[forcedfuel50]

I'm of the opinion we shouldn't be recommending any cells for stacking (two in series). I no longer recommend any customer stack batteries in Super T's P+18650, regardless of battery type or brand. With products becoming available such as the Kick, it will further reduce customers need for stacking batteries to gain higher voltage.

I don't feel we can take the position that "they'll do it anyway" so we might as well recommend something "safer". When manufacturers recommend something all the customer thinks is it's approved and safe. You can't tell someone, don't do this it's unsafe and then in the same breath go *wink*wink*, if you're going to install them, use these.

 

[Stosh]

My favorite batteries to use in a 18650 tube mod are the 4.8v NiMh 4 ea. stacked, I've had a connector fail catastrophically, dead short, and the batteries do not vent, explode or even overheat. The batteries discharged completely but are still serviceable after recharging. Considering the developments in the news and on ECF lately, they are my go to power source for over 3.7v single cell vaping.

I also use NiZn 1.6v batteries but they are only available in AA so will not work for my tube mods.

 

[AriM]

I'm of the opinion we shouldn't be recommending any cells for stacking (two in series). I no longer recommend any customer stack batteries in Super T's P+18650, regardless of battery type or brand. With products becoming available such as the Kick, it will further reduce customers need for stacking batteries to gain higher voltage.

I don't feel we can take the position that "they'll do it anyway" so we might as well recommend something "safer". When manufacturers recommend something all the customer thinks is it's approved and safe. You can't tell someone, don't do this it's unsafe and then in the same breath go *wink*wink*, if you're going to install them, use these.

Boost regulators are even LESS safe than stacking, because they ask for all of that juice (to boost) from a single cell. For example a kicked running in an 18650 tube mod would require roughly 5 amps (at max load) from a single 18490.

I am honestly blown away by this recommendation.

 

[AriM]

My favorite batteries to use in a 18650 tube mod are the 4.8v NiMh 4 ea. stacked, I've had a connector fail catastrophically, dead short, and the batteries do not vent, explode or even overheat. The batteries discharged completely but are still serviceable after recharging. Considering the developments in the news and on ECF lately, they are my go to power source for over 3.7v single cell vaping.

I also use NiZn 1.6v batteries but they are only available in AA so will not work for my tube mods.

+1. Agreed the NiMh is very safe. They are also my current favorite (pun?)

 

[forcedfuel50]

Boost regulators are even LESS safe than stacking, because they ask for all of that juice (to boost) from a single cell. For example a kicked running in an 18650 tube mod would require roughly 5 amps (at max load) from a single 18490.

I am honestly blown away by this recommendation.

Don't be blown away, instead here are the specs on what makes a single cell Kicked device extremely safe compared to stacking two cells:

-First, you are using a single cell with the Kick,

-Second the Chemistry of the AW IMR 18490 is a LiMn

-Third, the AW IMR 18490 is rated for 10C (over 10amp continuous discharge!)

-Fourth, the draw on the Kick is only 4 amps so we have over twice the needed battery capacity to safely drive it!

-Fifth, the Kick has low voltage shut down, reverse polarity and short protection circuits.

 

[AriM]

Don't be blown away, instead here are the specs on what makes a single cell Kicked device extremely safe compared to stacking two cells:

-First, you are using a single cell with the Kick,

-Second the Chemistry of the AW IMR 18490 is a LiMn

-Third, the AW IMR 18490 is rated for 10C (over 10amp continuous discharge!)

-Fourth, the draw on the Kick is only 4 amps so we have over twice the needed battery capacity to safely drive it!

-Fifth, the Kick has low voltage shut down, reverse polarity and short protection circuits.

So in your opinion it's safe to draw 4 amps (over 11amps at 10c) from a single 18490/18350? (you , as a vendor, will personally endorse a 10c rating?)

What if the unprotected cell dead shorts in the tube, before the kick ? the kick can't protect in that scenario....

Most protected cells have the same protection as the kicked, but it exists on the cell....not an external device. (well arguably, since the protection PCB is external to the battery)

Do you have any testing to back up that an IMR 18490/18350 can safely take a dead short, or a continuous draw of 4 amps? I would like to see the temperatures of the cell in that kind of scenario.

I will be providing this data in the coming weeks (with proper discharge/load tests)....to show that it is or is not in fact "safe"

I am not posing a challenge to anyone here, just offering to qualify (or disqualify) the claims being made....

 

[Stosh]

+1. Agreed the NiMh is very safe. They are also my current favorite (pun?)

If you like NiMh, you'll love NiZn with an extra 0.4v per cell, they just need them in more different sizes.
They seem perfect for our application, with a higher voltage, and SAFE...

 

[AriM]

If you like NiMh, you'll love NiZn with an extra 0.4v per cell, they just need them in more different sizes.
They seem perfect for our application, with a higher voltage, and SAFE...

Yes I have tried them. I wish they had one in a sub-c size, so we could stack 4 (and maintain the size of an 18650).

 

[rolygate]

@Stosh - Ni-Mn and Ni-Zn cells
At some point we could maybe start to advocate for mods built to use these 'safer' types of batteries. That seems a good move to me if these batteries really are a better prospect.


The Kick
I have been told the Kick, in practice, will deliver a maximum of 10 watts. If that is true, then perhaps it cannot overdrive a battery? Although I suppose that depends on what the definition of 'overdriving a battery' is. The little Tenergy Li-FePo4 cells seem to be able to take a huge overload without problems. Provided you don't get a counterfeit one.

 

[rolygate]

@FF50
It is true that stacking batteries is inherently risky because of things outside the control of both the mod maker and the user. For example the batteries may be counterfeit and not what they say on the label. However, users will always stack batteries and this problem will not go away. Any tube mod that accepts an 18650 will at some time have two batteries put into it.

My preference is not to ignore a problem but to find some way of dealing with it. In this particular case, we have to meet it head on because of the media interest in exploding mods. This is hurting us and we really don't need it. Part of the problem - some would say all of the problem - is the batteries being used. If there is an option for a non-explosive solution for 6v vaping then we must advise members of that fact. We have to tell them it is dangerous to use two unprotected Li-ion cells, and that some other cells may not be up to the job.

But once you've told them battery X is no good, you have to tell them battery Z can be used.

People are always going to do this and there is no way to stop it being done. We have to fix the damage somehow.

 

[Rocketman]

I've noticed the flack you've gotten for recommending things as an 'official' of ECF and I understand your feeling of responsibility to the 'community'. I imagine that some of the lessor experts agree with you but find excuses to disagree because of your position, not your objectives, or your qualifications. Something has to be done, agreed, and the open discussion approach you are taking now has a good chance of getting more of the 'experts' to actually contribute rather than fight the concept of driving mod makers and resellers to build a safer product.

If 'we' can recommend a safer stacked battery combination and highlight that counterfeiting is rampant is the Li-ion market that would be a plus for the community. Then figure out a way to make this info highly visible to a 'Noob'.
and highly visible to our vendors, so they KNOW we are watching them