Preliminary testing with the DNA30

[mamu]

Been testing this DNA30 off and on for the last few weeks and so far so good.  I love the new watts lock feature! 

With the range of 7W to 30W, I got 0.1 - 0.2 voltage difference from what the DNA display showed to what the watts meter showed with the watts meter displaying the lower value.

With regard to watts, I got from 0.3 - 0.6 watts difference from 7W to 20W with the watts meter reading the higher of the watts, and 1.5 watts difference from >20W with the watts meter reading the lower of the watts.

So all that is pretty good news.

Did some testing with voltage drop under load with 2 of the better 18650 30A batteries - Sony and LG. 

LG 18650 30A 2500mAh battery...


Sony 18650 30A 1600mAh battery...

[kortt]

Cool mamu, thanks for sharing.  Any eta on your dna30 mod? 

[CraigHB]

Not much to say about the DNA30 I haven't already, but that's some interesting test data on those cells.

It looks like the LG cells compare nicely to the Sony cells.  I would expect that to be the case since they list similar resistance specs, but you never know for sure until you check.  Pretty amazing they carry 900mAh more charge.  May use those for the next one I do with 18650s.  I need to actually, the LiPos I'm using are good for pretty high outputs, but I'm limited with the 18650s I used last time.

It's somewhat limiting using an atomizer to provide a test load.  It's pretty easy to make a load bank with some sheet aluminum and wire wound resistors.  That way things can be loaded indefinitely.  Just solder the resistors up in series with bare solid wire.  Tap them at various places with test clips to adjust resistance.

Here's some resistors like that.

Here's the clips I use.  They can actually handle a good amount of current, pretty much anything you'd throw at them with a load test.

[Visus]

Exxcellent batts
also most awesome they are not the 4.35 cells that lg usually uses for high current batts..

Mamu is that your custom phoenix atomizer?   I read about that a long while back was gonna try to build it..
I did not but was most impressed..

[mamu]

@kortt - I can't decide which enclosure I want to use for this DNA30, so I've been putting it off.   

@Craig - I'm really impressed with the LG battery, too.  I vaped several days with the LG batts on the Raptor.  Cutoff voltage was 6.4v - and that was vaping at ~16W.  So a bit higher cutoff voltage than the Sony, but the extra days I got in vape time was great.

@Visus - the Phoenix is also the Bulli.  Nice cheap RDA.  If I ever should go the dripping route, I want to get a Quasar RDA. $$$$ though. 

This video shows the difference in voltage drop under load without battery contacts...

[Visus]

Wow the Bulli is expensive as is the Quasar
both very nice

 Thanks for the heads up..  I have todd reviews on my yt,  I skipped over the Quasar thinking, "oh boy another dripper"--not watching that lol
but that is a really cool dripper.. a few lifetimes piece.

This is awesome on load testing, I assume  it's even better wired in a mod.  It appears as a long run and there possibly is some loss there.  Craig gave the 6" lossage and it seems would be a resistance -mohm value as well as being on a breadboard..

[Breaktru]

Very good mamu. Thanks for sharing your testing with us.
I don't have much fate in using a test board for high amperage connections.
Although I see less of a voltage drop when you soldered the leads to the battery, I solder my batteries straight to the dna input and a good quality battery holder and solder wires w/ alligator clips to the output. For a load I use a lenght of 28 gauge kanthal and move the aligator clips to get a particular ohmage and I also use wire wound resistors.

Well done 

[CraigHB]

@Craig - I'm really impressed with the LG battery, too.  I vaped several days with the LG batts on the Raptor.  Cutoff voltage was 6.4v - and that was vaping at ~16W.  So a bit higher cutoff voltage than the Sony, but the extra days I got in vape time was great.

Thanks for that test there.  I guessed 10 mOhms for the battery contacts and it looks more like 20 mOhms, that's a lot considering the battery is only 13 mOhms.  Anyway, yeah that's the benefit of soldering cells, you eliminate any losses from the battery holder.  Though, the data sheets for the round cells all tell you not to solder them.

Yes, the breadboard also introduces some resistance.  You should see a drop of about 150mV at the battery so the breadboard and wires are responsible for the other 150mV.  The wires are probably dropping a good chunk of that so the breadboard is probably not all that much. 

The good breadboards use quality contacts that make pretty good connections, but even so, the parasitic impedance you get from a breadboard can be a problem for some things, usually it's only the high frequency stuff like high speed comms or RF.  For that stuff, I use a breadboard in a modular fashion by making little proto PCBs to plug-in to the breadboard.

[CraigHB]

For a load I use a lenght of 28 gauge kanthal and move the aligator clips to get a particular ohmage and I also use wire wound resistors.

I use a load bank of wire wound resistors usually, but I also have a coil of 16 gauge nichrome I use when I need to adjust load in a vernier fashion.  So I do the same thing there.  The load bank works better, but I only have a discrete set of resistances available.  When I need to adjust load in an analog fashion, I use a coil of heavy heating wire.

[bapgood]

Ok watched the videos and here was I got.

LG single in holder - ~0.54v drop
LG dual in holder - ~0.32v drop
Sony single in holder - ~0.46v drop
Sony dual in holder - ~0.28v drop
LG single no holder - ~0.31v drop


So with the vdrop being fairly close the LG's look awesome!!!, since your basically getting 900/1800 more mAh

My LG's are out for delivery!!!.....Can't wait to thaw them out and get them charged

I would say your battery holder is doing ok, when I was testing a FT battery holder it wouldn't even fire the DNA at 30w with a single battery. 

Like Craig said the breadboard will add resistance (mine are horrible)....I even noticed that when I hooked mine HK meter between the battery and the DNA that it was adding enough resistance to the DNA input that even a good single 18650 was struggling at 30w, but with the meter removed or moved to the DNA output the same battery worked fine.

[bapgood]

Not much to say about the DNA30 I haven't already, but that's some interesting test data on those cells.

It looks like the LG cells compare nicely to the Sony cells.  I would expect that to be the case since they list similar resistance specs, but you never know for sure until you check.  Pretty amazing they carry 900mAh more charge.  May use those for the next one I do with 18650s.  I need to actually, the LiPos I'm using are good for pretty high outputs, but I'm limited with the 18650s I used last time.

It's somewhat limiting using an atomizer to provide a test load.  It's pretty easy to make a load bank with some sheet aluminum and wire wound resistors.  That way things can be loaded indefinitely.  Just solder the resistors up in series with bare solid wire.  Tap them at various places with test clips to adjust resistance.

Here's some resistors like that.

Here's the clips I use.  They can actually handle a good amount of current, pretty much anything you'd throw at them with a load test.

Craig, Do you have a pic of your load bank? I have plenty of sheet aluminum 

[CraigHB]

Here's one attached.

Those black things on the back are heat sinks.  The resistors are bolted down with thermal grease underneath to get good transfer to the sheet aluminum. 

It's taken a beating through many builds and has held up quite well.  I made it some time ago before I did much with sub-Ohm coils.  I actually need to rework it with 100m and 200m resistors for more steps with the sub-Ohm stuff.  Right now it just has 500m and 1 Ohm resistors.  There's a one big 50W resistor on there, but it would probably be fine with all 25W resistors.   

The thicker the better on the sheet.  The sheet on the one pictured is 1/16" but 1/8" would be better.  I have another one that is an active load bank with electronics on it where I used a thicker sheet.  That one is a precision 4A current sink I use for calibration.  The thicker sheet dissipates heat a lot better.

[bapgood]

Preliminary IR results are in for the LG's

Just a couple of notes....the LG's are FOB and not broke in by any means, so I will be checking them every couple of charges to see how the IR changes over break in.....also I noticed that the Sony batteries give a lot more stable reading, the LG's bounce around a little more....possibly due to the Sony's being broke in??? Also I was kind of surprised that the Sony's went exactly half with two batteries and LG's didn't.

[mamu]

wow - thanks for that, bap.

Did you get any of the 26650 50A batts you linked me to a while back?  I got them in the other day and so far so good - still vaping with Sam on the 1st charge.

[bapgood]

wow - thanks for that, bap.

Did you get any of the 26650 50A batts you linked me to a while back?  I got them in the other day and so far so good - still vaping with Sam on the 1st charge.

lol....I was going to, but I don't currently have a 26650 mod so I decided it would kind of be pointless

Too many projects going to restore or build a 26650 mod right now.

[mamu]

I can't wait to see some of your projects, bap.  git er done already. 

[bapgood]

This is kind of funny....I got a little impatient before and pulled them off the charger before they were all the way charged. Didn't think it was a big deal because from what I have seen it doesn't make much if any difference of charge, however what I think was the difference is letting them settle after charging. The first time they came right off the charger and tested, this time they had set for about hour after being fully charged.

So now they match the Sony's and read just as stable.

[bapgood]

Just as an FYI (maybe this is common knowledge and I'm slow)....but with the new wattage lock feature I was thinking it would be kind of nice and cool to have a third button just for the wattage lock, a button that would essentially press both buttons at the same time. I had thought that since the up/pot didn't share a common ground that it couldn't be done, but I got playing and found that if you take the center up/pot pad to ground that it works!!! So then I wired it and the down + together to one side of the switch and down - to the other side of the switch and bing-bang-boom...press the switch for ~5 seconds (which seems like forever) and now you have a single wattage lock/unlock button

[CraigHB]

That's a pretty good read on the internal resistance characteristic (looks like a handy meter) and it's good to see the LGs and Sonys are similar as they are.  Thanks for posting that.

Just a couple of notes....the LG's are FOB and not broke in by any means...

I haven't noticed any of the Li-Ion batteries I've used exhibit any kind of break-in.  Typically they perform to full specifications on the first charge.  If anything, they seem to have extra charge capacity on the first few charges then settle into a slightly lower capacity for the bulk of the duration.  I think the idea of break-in comes from older rechargeable technologies.  Li-Ions are supposed to be free of that.

I think was the difference is letting them settle after charging.

It depends on the charging rate and how warm the cell gets, but the internal resistance is somewhat temperature dependant.  It goes up a bit when the cell is warm.  So, if you let a cell cool after charging, it might read a little lower.  Also, resistance is slightly higher when the charge is lower and slightly lower when the charge is higher.  It really goes up when a cell gets close to being fully discharged.

You're also measuring the contact resistance and the resistance of the wires so you should take care that both the batteries and contacts are free of grease.  Also the contacts should be free of any tarnish.  That will ensure an accurate reading as possible.  Dirty contacts can cause unstable readings.  They need to be tight and pretty much squeaky clean.

[bapgood]

I haven't noticed any of the Li-Ion batteries I've used exhibit any kind of break-in.  Typically they perform to full specifications on the first charge.  If anything, they seem to have extra charge capacity on the first few charges then settle into a slightly lower capacity for the bulk of the duration.  I think the idea of break-in comes from older rechargeable technologies.  Li-Ions are supposed to be free of that.

I haven't noticed it much on the round cells, however  I had some POS MNKE 26650's that seemed to get longer run times after a few cycles. Using lipo's in RC I have noticed better and longer performance after a few cycles.

I have heard (not sure if its true or not) that battery manufactures add some kind of stabilizing agent to the cells to increase the shelf life of the cells, and after a few cycles it is broke down or something and no longer effects the cells???

You're also measuring the contact resistance and the resistance of the wires so you should take care that both the batteries and contacts are free of grease.  Also the contacts should be free of any tarnish.  That will ensure an accurate reading as possible.  Dirty contacts can cause unstable readings.  They need to be tight and pretty much squeaky clean.

10-4....contacts are tight and clean. Not much I can do about the wires, but they are some heavy wire. Originally I tried soldering on some 20g leads that I could either but some gold plated bullet connects on or just wire nut so I could disconnect the holder easier, but doing so increased the reading by ~10 milliohms so I soldered the heavy wire back on so the readings would match previous readings when I had the wires soldered to the battery holder.

I don't expect that a $40 China meter is going to be extremely accurate, but I figured it should be accurate enough to compare readings of different batteries taken on the same meter.

[CraigHB]

I have heard (not sure if its true or not) that battery manufactures add some kind of stabilizing agent to the cells to increase the shelf life of the cells, and after a few cycles it is broke down or something and no longer effects the cells???

Could be the case for the 18650s.  Makers do all kinds of different things chemically with those to improve performance.  The LiPos are all made in China with the same process and chemical composition so it's doubtful there's anything special going on with those.  You find LiPos with different C ratings, but it all comes down to the physical construction of the cell, thicker plates for higher C ratings and lower charge capacity, thinner plates for higher capacity and lower C rating.  Like any other cell, the performance can vary with the brand depending on the level of quality control the maker uses in production.

[Visus]

Ya' we all learned from a batts guy, "that lipo's will reduce in resistance after a few charge cycles some almost halve it."  So hopefully it is the same chemistry in 18650's.. 
 

[CraigHB]

Round cells like the 18650s are quite a bit different from the LiPos in both construction and chemistry.  There are round LiPos, but those are just the same thing as the flat ones with the plates rolled instead of folded.  The Japanese companies put a lot of effort into R&D with the round cells (most notably the 18650s).  They've come through with some pretty big advancements there.

LiPos don't see nearly the kind of development put into them as the Japanese round cells, they're kind of like your basic mass-produced Li-Ion cell without large amounts of development going on in the background.  The 18650s are really on the forefront of Li-Ion battery tech.  The Japanese companies do make "prismatic" Li-Ions that are similar in construction to the Chinese LiPos.  Like the round cells, those have more development behind them.

As far as individual variations of internal resistance, I can only speak from my own experience with the range of LiPos I've used.  I've not noticed drastic changes of internal resistance over the first few charge cycles.  It's something where I pay close attention since it's a limiting factor for my electronics designs.

[Visus]

Agreed Craig heres the post I was quoting about halving the IR, "it isn't common but does happen,"  I, we,  hoping it was very common..  
It makes a huge difference in run times..

http://www.e-cigarette-forum.com/forum/battery-mods/510566-battery-internal-resistance-measurements-3.html#post11793201

ok heres the quote

Most I've seen IR drop after break in is about half the virgin value, but generally it's much less than that... FWIW

Noone likes the truth sometimes 

[CraigHB]

Yes, it makes a difference.  The heavier the load the bigger the difference.

You can look at it in terms of power loss.  For example a cell with say 70 mOhms internal resistance (typical for a 2C 18650) will lose about 2.5 Watts at its maximal drain of 6 Amps (current squared times resistance).  A load of 6A will result in a power consumption of about 22 Watts (nominal voltage times current).  That's over 10% lost as heat in the cell.

A cell like the Sony or LG with about a fifth of the resistance will only waste a fifth of the power.  A good amount more of the cell's energy is delivered to the atomizer instead of wasted as heat in the cell.

Of course, the high drain cells don't have as much capacity as the 2C cells so you have to consider that as well.  For lighter loads, you'll get more run time with the 2C cell, but for heavier loads, you may get more run time with the high drain cell even though capacity is somewhat lower.

That's especially the case when running a 2C cell over its continuous drain limit.  It's acceptable to load a cell up to 50% over it's continuous drain limit when powering an atomizer since atomizers are not powered continuously.  The cell has time to cool so it can be loaded heavier than the continuous drain limit, but within reason.  It's still a good idea to observe the continuous drain limit since it provides a wide safety margin.