Why I Come Down On Certain Batteries.

[chykensa]

Ripshod - a great post, and just what this forum is for. Like some others I don't have a clue about batteries, but havoe always only ever bought from Torchy or Ecolux via eBay which have been recommended many times by other more knowledgeable forum members.
A list of good quality batteries with all the safe useage figures laid out in a chart would be a great resource for numpties like me - I can use Steam Engine to wrap a coil, but that's about as far as my knowledge of Ohm's Law goes, so I for one would be really grateful for something like this.77
Isn't it concerning though that some retailers, either unwittingly or not, are selling batteries which are really not up to specifications and could cause a serious injury to a user?

[lisburnvapes]

Most popular batteries are being cloned, cloned is probably not the right word as a clone is an exact copy, you just have to look at the likes of Ali or Dhgate to see all the batteries purporting to be genuine, even the 25r is being faked, I think a list of trusted vendors would be of more use than a list of recomended batteries , just my tuppence worth, but great to see the more knowledgeable members drawing up some sort of list, cheers guys

[Ripshod]

After discussion via PM with another member it's apparent there's good and bad ones. The fact is AWT are rewrappers, the batteries can come from anywhere, the spec says 0.08ohms or less, so it can be easily assumed there's AWTs out there with really low internal resistances. A look at the candlepower forums confirms that, though there is a suggestion it's a 20Amp cell.

I got bad examples, which are within spec (apart from the current) and there are better ones out there. Is it worth a gamble?

[tomj777]

Thank you, Ripshod

This is as fascinating as it is perhaps alarming.

Regarding the AWT's, I have a 2500MAH 35A and a 2600MAH 40A

I found myself wondering what, assuming a 0.05 ohm internal resistance, a sensible Watt limit would be with a 0.15 Ni2000 coil or a, say, 0.5 Kanthal coil would be (and thus, although I can work this bit out, the continuous discharge Amp limit) on each.

Or would you advise some insulating tape on each end and consigning to a battery recycling bin (in case I've underestimated the enormity of the problem)?

[monty]

With batteries it is horses for courses and buying from a reputable dealer is not always enough. You need to try and get your head round what Ripshod is saying.

A quick way to check whether the internal resistance is low enough is to look at how much power you are intending to use with the battery and at what resistance coil.

a) If your coil has twice the resistance of the battery, it will take 67%* of the power and the battery 33%* of the power (Watts).
b) If your coil has 19 times the resistance of the battery, it will take 95%* of the power and the battery 5%*.

If you have an AWT battery ( with an internal resistancs of 0.04 to 0.05 Ohms) case a would be a nickel build of about 0.09 Ohms and case b a Kanthal build of 0,9 Ohms.

The moral is - if you are planning to use a nickel build check the internal resistance and do the sums.
If you've bought AWTs best not to subOhm but these batteries are sold by reputable vendors because they are fine for many applications.

* This is fairly close to reality but ignores the resistance at connections.

[Deleted]

A very good thread which should help peeps make an informed decision . Personally I only buy my batteries from 3 Vendors as they are known to privide the genuine article .
Those being Torchy, Ecolux and Myepack and battery of choice for me is the Samsung 25r, I think it would be a great asset to the forum to have a thread where folk can select a good battery and maybe a list of known vendors that are also known to be supplying the genuine product .

Also good practise when building, coiling etc, make use of Steam Engine, which has a number of different calculators to keep you on the right track

[Ripshod]

4 wire testers are cheap enough these days, and once calibrated can measure the IR to give a good indication of the capabilities of a cell. Even uncalibrated they can give a good indication by comparison.

I'm not suggesting everyone buys one, but would it be unreasonable to ask a vendor to make one part of their arsenal? Takes 5 seconds to test, the battery doesn't need charging for an initial test and it'll take negligible power from the cell. Would also prevent the fiasco we had last year with a vendor having to recall the fakes they sold. Protection for everyone.

Torchy tests his!!

[Deleted]

May 23, 2015 8:58:15 GMT Ripshod said:

I'm gonna try and keep this simple, although the fact is it isn't. What I'll attempt is to condense all the info into bite sized chunks that are easy to digest.

There are lots of new cells appearing making wild discharge current claims. So what I'll do is take one specific cell (the AWT 40Amp 2600mAh 18650 from Gearbest) and show you why it won't do what we're lead to believe by numbers.

Ripshod

I posted the link to those batteries in Gearbest.

I should have added when I did that I wouldn't link to any batteries I hadn't tried my best to investigate first.

And while I couldn't find the testing specs for the 40A......these are the ones for the 35A

lygte-info.dk/review/batteries2012/AWT%20IMR18650%202500mAh%20%28Yellow%29%20UK.html .......which look pretty good to me.

Also, for everyone else its worth saying that what I will try are not necessarily what you should try.

Follow the excellent information given in this thread on battery safety and recommendations.

[Deleted]

Oh......I should also add that these batteries were for the stuff I'm using for the Subtank and the like.

It will get used for 26w.......at 0.6 ohms.......so not anywhere near pushing the envelope with them.

[Ripshod]

Those are the same results as posted on the candlepower forums. You can see quite clearly how the batteries fall of rather quickly over 20Amps. It is a good result - but the point is these batteries are inconsistent and I seem to have 2 examples of the worst extreme of that. Having said that they are within the spec, but hardly capable of holding voltage at higher currents with the IR they have. And the IR in the spec should ring alarm bells everywhere, 0.08ohms? 20 Amp batteries have an IR better than 0.02ohms, 30Amp better than 0.015 Ohms. The higher the IR, the lower the usable Current and the higher the temperature per Amp.

[Deleted]

As I said.....these are for 26 watts at 0.6 ohm........I'm going to pull about 6.5 amps

Even if I were to do a 0.2 ohm build and run it at 60w .......It's about 17 amps.............so still under the 20 amps.

As my preferred builds come in around 0.4.......sometimes 0.3...........I'd need to push 160w at the 0.4..... or 120w at the 0.3 to hit 20 amps

I've only ever gone up to 80 watts once to see what it's like.

I'm usually at about 50 watts.

BUT.........even if I do want to do all that and maybe go lower even I have VTC4's and Samsung 18650 INR18650-25R 2500mAh batteries for that.

I'm pretty sure I'm within my safe limits using these for a Subtank setup.

Ok.....all that said I applaud what you're doing for everyone to show which batteries are safe...... and at what levels....... for the forum.

It will be an invaluable reference and if it includes links to trusted vendors too, something that everyone should Bookmark

[Ripshod]

Great suggestion re the vendors guide kreed. hijack has already done a buying guide, I hope to expand that and include it, er..... later

First thing is to make a shortlist from all the suggestions in the other thread, to include the most popular and safe vfm batteries there are (obviously I won't be able to cover them all). Any found to be unsuitable will not be included to avoid any confusion, rewraps will be in a separate cross-reference list to include batteries like the 35Amp (20Amp) efest.

Where possible I'll provide links to specifications/pdf (those I can source) for anyone that wants them. It certainly isn't gonna happen overnight, more in stages. The Power Chart is the first project.

Thanks for the support everyone, I feel I'm gonna need it 

[Deleted]

It will be a great achievement if you pull it all off Ripshod considering the amount of work involved

I'll happily help out if I can

[Ripshod]

May 23, 2015 18:51:57 GMT kreed said:

It will be a great achievement if you pull it all off Ripshod considering the amount of work involved

I'll happily help out if I can

Appreciated. I may call on you  thumb up

[monty]

May 23, 2015 12:44:14 GMT tomj777 said:

Thank you, Ripshod

This is as fascinating as it is perhaps alarming.

Regarding the AWT's, I have a 2500MAH 35A and a 2600MAH 40A

I found myself wondering what, assuming a 0.05 ohm internal resistance, a sensible Watt limit would be with a 0.15 Ni2000 coil or a, say, 0.5 Kanthal coil would be (and thus, although I can work this bit out, the continuous discharge Amp limit) on each.

Or would you advise some insulating tape on each end and consigning to a battery recycling bin (in case I've underestimated the enormity of the problem)?

If the batteries internal resistance is 0.05 Ohms then with a 0.15 coil a quarter of the power will go in heating the battery so at 20 Wattts that would be 15 Watts going to the coil and 5 Watts to the battery. 5 Watts heating the battery doesn't sound good to me.

A couple of years ago we didn't have the batteries we have today and the AWT's specs back then would have been thought very good. But back then a 0.15 Ohm coil would have been described as nearly a short. Certainly no need to chuck the batteries but I wouldn't use them with Nickel.

If you are using a regulated mod with Kanthal it is nearly always better not to subOhm. Put a 1.5 Ohm coil on your AWTs and you're absolutely fine at 50 Watts.