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Thursday, April 10, 2014

Sony 30A - Wherefore Art Thou...??

Over the last few weeks there has been much discussion between myself and Mrs. Wolf regarding the issues of battery safety with respect to mechanical mods, cloud chasing, and so on has occurred at the vape shop (K & D Vape Shop).

First some background.  Vaping involves either "regulated" power or "unregulated power" for the most part.

Unregulated power is basically a battery connected to a coil of wire such that when the battery is connected to the circuit the wire heats up.  In the case of vaping this generates the "vapor."

There are several vaping-related issues with this.

For one, batteries do not emit a fixed, continuous voltage (and hence power level).  When you charge a 3.7V battery fully the voltage is actually 4.2V.  As its used it "runs down" to about 3.6V at which point its completely discharged (you can run it down to 0V but it won't recharge).  So your vaping experience changes over the charge of the battery charge, i.e.,  it might be too much at the start of the charge or it might be too little at the end - in any case there is zero likelihood it will be "just right" for long.

The charge level affects the flavor - more charge means more "throat hit"and nicotine.  Similarly more charge means more vapor which implies more nicotine absorption.  (Imagine the volume of a single huge "cloud" versus twenty tiny clouds.) So your battery level impacts your overall vaping experience.

Regulated power means that there is a control that sets your voltage and as long as the control can maintain that exact voltage it does.  So your vaping, nicotine and so on are "controlled" accurately until the battery dies.

The downside is that the regulation consumes power, i.e., adds overhead, so your battery life overall (as well as your maximum possible power level) is reduced.

Mechanical mods are, for the most part, unregulated (though there is no reason you couldn't build a mechanical regulator).  Instead, they are manually "regulated" by turning them on and off (which is actually what regulation does in the mod world anyway).

So the issue with respect to battery safety becomes this:  What happens when I run a Lithium Ion (or LI variant) through what appears to the battery as a near short, i.e., low ohms or sub ohms?

And what batteries should a shop own offer to people using these types of mods?

The most popular battery today for mechanicals, at least in our neighborhood,  is a "30A Sony" battery.

So, Mrs. Wolf asks, should we sell these 30A Sony batteries?  Are they Safe?

The easiest way to answer this question, I reply, is to "check the specs."

"Specs" are data sheets published by people who build electronic or other devices that outline what the device is and is not capable of doing.  How it should be or should not be used, what happens when you abuse it, how you shouldn't abuse it, etc.

So, after this question, as well as some discussions with other vapers who have stopped into the shop, I set about looking for "specs" on the "30A Sony" battery.

What I would expect to find is an offical Sony Energy Devices (a unit of Sony that actually makes batteries) document that describes this battery - its spec sheet.  The idea is to check these specs and see if the battery is designed to adequately work within the context of a mechanical mod.

But I didn't find this kind of spec sheet.

Instead I found variations of what looks like some kind of PowerPoint (there are several different ones) that look like this.

So it would seem that the "30A Sony" battery is what this chart (taken from the link above) describes.

(If anyone finds a more detailed or specific Sony Energy Devices document I'd like to see it.)

But let's look at this in a little more detail.

First off, remember that batteries are basically "dead" at 3.5V.  So if we inspect this chart we see that at heavy discharge loads (here greater than 20A) the battery comes "out of the gate" dead more or less.  (Note too that the discharge test terminates at 2.5V so no battery goes below this threshold.)

In my experiences designing the GRX 1.0 board for the PrimusZ a battery is pretty useless at 3.5V.

But this is where the 30A seems to start (more or less).

So my thinking is that this battery isn't designed any different than any other in its class and the 30A is coming from this chart.

So what do batteries actually do in a situation like this?

This video (thanks, Erik) gives a pretty good idea:

Basically this guy is comparing the voltage drop across two different mods.  But he is also showing how batteries actually work in a mod.

The first mod emits 3.92V into a .58 ohm load during the test, thus the battery is producing 3.92V/.58 ohms or about 6.7 amps of current.  This works out (using 3.92 x 6.7) to about 26.5 watts.

No where near the "30A" stamped on the battery.

So what are we as a shop looking for in a battery?

Several things:

1) Safety - how does the battery perform when shorted out, i.e., does it catch fire or explode.

2) Reasonable discharge performance into a typical "sub ohm" load.

3) Documentation - does the battery come from a place where we can have some understanding that we know where it came from and how it will work, e.g., reliable, manufacturer-written specifications?

4) Sourcability - can we get this battery more than one time from more than one source? (Batteries are upgraded all the time as the chemistry improves so we really want a reliable battery family...)

So here is a review of a similar battery to what we might use (we actually chose the 15Q).

What's important is probably this chart (from the link above):

This tells us how long the batter will last when churning out 6.7 Amps - about 6-7 minutes before the level falls below about 3.7V.

(And see, this battery is also a "30A" battery if you look at the chart closely enough...)

So what's the bottom line?

We ended up with the SAMSUNG INR18650-15Q.

First, because the spec sheet tells us the battery can handle a dead short without exploding or catching fire.

Second, from research these batteries seem to be used commercially in a lot of tools like drills, etc. and Samsung SDI seems to be a supplier in this market.

Three, we can get them (or newer version) from commercial suppliers.

Fourth, the would appear to have the appropriate amount of power required for a mechanical.

And, with apologies to the guy who made the video above:

The .08V difference between the two modes represents a 1 in 100 (or 1%) accuracy.  I highly doubt the meters used (ohm and power) are that accurate so though one mod "beats" the other you'd have to do a more scientific experiment.

First, you'd have to sample a lot of batteries to see how much they vary (probably more than 1% in my experience).

Second, you'd have to check that the coil ohms value doesn't change as it gets hot or is heated (it does but I don't know how much in this case).

Third, you'd have to know how accurate and reliable your meter's are (.01 matters in these cases and the measurements in the video clearly bounce around).

The bottom line on the video: its probably showing a mostly normal "variance" between all the pieces and parts.

Presuming both mods are made of similarly conductive material I would not expect too much variation.

For those that are interested - stop down and we can discuss this in more detail if you like...

And yes, you can go far below the .58 ohms used in the video.

Yes, the "amps" to the coil goes up.

But this means also means the "voltage drop" worsens as the battery tries to compensate for what amounts to a direct short and your battery life of 6 minutes will decrease proportionally as well.

1 comment:

  1. Further investigation uncovers this link:

    I would expect Sony batteries to look like this or at least have this labeling.

    There is an Underwriters Laboratories link here:

    So it seems Sony makes something with that model number but the charging voltage and current look wrong (max charging current 12A and max charging voltage 12V).