My first attempt. DNA12 wooden box

[kortt]

Well, I'm not much of a carpenter, and don't have a lot of electronics experience other than guitar electronics, but here is my first stab at a box mod.






I have a visual disability so anything like this I do under my CC TV magnifier.  I'd be lost without this thing.


The mod uses an AW IMR 18650 2000mah battery and i notice at about 3.6 volts the DNA module starts pulsing and the red error led blinks.  Would this be due to voltage sag from the battery under load?  Could it be from something else?  I'm wondering if the trimmer pot I used is not quite right.  I don't have enough experience with this stuff to troubleshoot it properly.

Here are some of the components:

10k thumbwheel trimmer, 3A toggle switch, 3A PTC fuse.

I have noticed that no one seems to use Li-on flat cells in mods, only Li-Po cells.  Is there a reason?  Do the Li-on flat packs have insufficient discharge rating or something?

[jomurp]

Nice work  Looks good to me 

[Breaktru]

Well, I'm not much of a carpenter, and don't have a lot of electronics experience other than guitar electronics, but here is my first stab at a box mod.


I have a visual disability so anything like this I do under my CC TV magnifier.  I'd be lost without this thing.

The mod uses an AW IMR 18650 2000mah battery and i notice at about 3.6 volts the DNA module starts pulsing and the red error led blinks.  Would this be due to voltage sag from the battery under load?  Could it be from something else?  I'm wondering if the trimmer pot I used is not quite right.  I don't have enough experience with this stuff to troubleshoot it properly.

Here are some of the components:

10k thumb wheel trimmer, 3A toggle switch, 3A PTC fuse.

I have noticed that no one seems to use Li-on flat cells in mods, only Li-Po cells.  Is there a reason?  Do the Li-on flat packs have insufficient discharge rating or something?

Hey Kott. Nice going man. Looks great. Congrats.

The CC TV magnifier is pretty cool. I may look into that.

The battery should be able to handle DNA12. What atty resistance are you using? The Red Fault LED will illuminate when it you exceed the wattage for the coil resistance. Have you tried tuning down the wattage when that happens? Also try a higher ohm atty.
A 1K to 10K pot is recommended. I used a 10K like you did.

Li-on flat cells, have never used one but from searching a bit just now, I think that you can get more "C" ratings and less internal resistance with a Li-Po for cheaper.

[kortt]

Thanks guys

The CC TV is a 19" Acrobat LCD.  They are a bit pricey.  Check it out here: http://www.enhancedvision.com/low-vision-product-line/acrobat-lcd-desktop-video-magnifier.html

I'm using cartos ranging from 1.5 DC, 1.7 SC to 3.0 SC.  So far I seem to be able to get 4 to 5 hours vape time with the mod which I think should be better with the 18650. It seems to hit around 3.6v and then start pulsing then the red led comes on solid after a few more attempts to fire.  It does this with any atty I try on it.  I was trying to measure the voltage sag on load and as far as i can tell it's about .2v.  Not sure what's up, but the datasheet says the low voltage cutoff is 3.1 under load for .25 seconds.  I'll keep digging at it and see if I can figure it out.

[CraigHB]

Looks good Kott, wooden boxes have a nice feel and they look nice.  You did a nice job on it.

The AW 2000mAh IMR cell you're using has the highest energy density of all the high drain cells.  That means you get the most capacity with the least amount of space.  The Panasonic CGR18650CH has a little higher energy density but it's not much and the Panny cell is 5C compared to the AW IMR cell which is 10C.  You'll get slightly less voltage sag with the AW cell and slightly more run time with a Panny cell.  Either cell should power a DNA12 with plenty of room to spare on drain limit.

A 10C or 20C LiPo cell has lower energy density than the round IMR cells.  However they have the least voltage sag.  They're nice in a box since they use space more efficiently in that kind of enclosure which somewhat makes up for their lower energy density.  The main advantage it they can put out a lot of power.  The DNA12 is not high power so it really would not benefit from a LiPo flat cell.  A high drain flat cell really shines when you put upwards of 20W on it.

I have not a seen a flat cell that uses a chemistry other than Lithium Polymer.  It's not just the chemistry, but the physical construction that is different.  All the flat cells are made that way as far as I know.   They do vary in drain limit quite a bit.  They can range from 1C to 60C.  The most common are the 20C ones used for hobby applications.  You can find 2C and 10C available as well.  The 2C ones are more common, but pretty worthless for our purposes.  The drain limit is too low on them.

[Breaktru]

Thanks guys

I'm using cartos ranging from 1.5 DC, 1.7 SC to 3.0 SC.  So far I seem to be able to get 4 to 5 hours vape time with the mod which I think should be better with the 18650. It seems to hit around 3.6v and then start pulsing then the red led comes on solid after a few more attempts to fire.  It does this with any atty I try on it.  I was trying to measure the voltage sag on load and as far as i can tell it's about .2v.  Not sure what's up, but the datasheet says the low voltage cutoff is 3.1 under load for .25 seconds.  I'll keep digging at it and see if I can figure it out.

Can you measure the battery voltage, NOT on the battery posts but at the furthest ends of each wire ends that come off the battery. Also do this while hitting the fire button.
There maybe a bad solder or battery contact connection causing a voltage drop.

Have you measured output voltage range? What's your lowest and highest.
Do you have all three legs of the pot wired in to the DNA board? It's hard to tell from the photo. I can't make out the 3rd leg.

[kortt]

Can you measure the battery voltage, NOT on the battery posts but at the furthest ends of each wire ends that come off the battery. Also do this while hitting the fire button.
There maybe a bad solder or battery contact connection causing a voltage drop.

Have you measured output voltage range? What's your lowest and highest.
Do you have all three legs of the pot wired in to the DNA board? It's hard to tell from the photo. I can't make out the 3rd leg.

Measuring the voltage at the battery inputs on the DNA gives me 4.00.  The battery itself measured at 4.01.

The voltage drop seems to be as follow:
Atomizer 2.3 ohms.  Measurements taken while firing the atty.
At Lowest setting on the pot voltage measured at the DNA batt inputs is 3.7
At Highest setting on the pot voltage is 3.2
Atomizer 1.8 ohm
At Lowest pot setting voltage is 3.6
At Highest pot setting voltage is 3.3

My wattage calculations are as follows:
1.8 ohm atty
Lowest setting 3.2v (5.6W)
Highest setting 4.7v (12.2 W)
2.3 ohm atty
Lowest setting 3.5v (5.3W)
Highest setting 5.4v (12.6W)

Not sure how accurate my calculations are.  I'm suing my VV Gripper to measure atty resistance.  The highest wattage figures seem too might to me as well.

As far as all three pot legs being attached, I'm as sure as I can be that they are and the ohms measurements at the DNA board contact points seem ok for the pot.

[Breaktru]

Measuring the voltage at the battery inputs on the DNA gives me 4.00.  The battery itself measured at 4.01.

The voltage drop seems to be as follow:
Atomizer 2.3 ohms.  Measurements taken while firing the atty.
At Lowest setting on the pot voltage measured at the DNA batt inputs is 3.7
At Highest setting on the pot voltage is 3.2
Atomizer 1.8 ohm
At Lowest pot setting voltage is 3.6
At Highest pot setting voltage is 3.3

My wattage calculations are as follows:
1.8 ohm atty
Lowest setting 3.2v (5.6W)
Highest setting 4.7v (12.2 W)
2.3 ohm atty
Lowest setting 3.5v (5.3W)
Highest setting 5.4v (12.6W)

Not sure how accurate my calculations are.  I'm suing my VV Gripper to measure atty resistance.  The highest wattage figures seem too might to me as well.

As far as all three pot legs being attached, I'm as sure as I can be that they are and the ohms measurements at the DNA board contact points seem ok for the pot.

Okay, the fact that your output voltage range was 3.2v to 4.7v and 3.5v to 5.4v tells me that the DNA is good. If you would have seen battery voltage through out the output range, I would have been concerned.

The Battery readings at the DNA seems to indicate that the battery maybe at fault with the Red Fault light coming on when the battery is 3.6v because it is dropping under load to 3.2v or perhaps lower. That's a significant voltage drop. My DNA12 cuts out at 3.2v
It's not the type of battery that is at fault but rather than the battery itself. AW IMR 18650's are super good batteries.
Or.............
A cold solder joint can produce a large voltage drop under load and show NO voltage drop w/o a load.
Cold solder joints may look fine. Wiggle the wire connection to see if it moves. They look dull when they should look shiny.

Update: One more thing of concern
Looking at the Battery Neg coil spring and Copper Pos contact, this could be a potential for failure due to a poor solder connection.
The metal in some coil springs I soldered to take some work to get solder to stick. I find filing / sanding, using solder paste and high temperature soldering gun is necessary. Same with the Pos contact strip.

[kortt]

You might be right about a cold solder joint.  I've got two of the AW IMR and two no name IMR's and the results seem to be the same with them all.

I have been thinking about tearing this thing apart and going over and maybe redoing all the solder joints again.  I'll have to wait till I get a new solder sucker since I busted my old one.   

I really want to thank you Breaktru and all the other awesome folks here who have the time and excellent knowledge to impart, and do so freely.  I've learned a huge amount since coming here! 

[kortt]

Update: One more thing of concern
Looking at the Battery Neg coil spring and Copper Pos contact, this could be a potential for failure due to a poor solder connection.
The metal in some coil springs I soldered to take some work to get solder to stick. I find filing / sanding, using solder paste and high temperature soldering gun is necessary. Same with the Pos contact strip.

The spring was a hassle to solder, yes.  Oddly enough, I think the solder joint on the copper pos terminal is ok.  I had to get one of thos hand held butane torches to solder it and I also soldered the 510 connector to the copper end plate using it.  My soldering iron wouldn't do it. The copper is from 3/4" copper pipe which I cut and sliced.  It's the right dia for a tube mod, maybe I'll make a copper tube mod down the road.

[kortt]

I think I may have found the trouble I was having.  The pos lead to the DNA's input broke off the other day while I was inspecting the connections.  After a closer look, turns out the pos lead was only attached via a few strands of the wire.  I must have done a crappy job when stripping the wire and cut off 75% of the strands on that end...duh.

Anyhow, my new solder sucker came today so back to the bench it goes.

[Breaktru]

I think I may have found the trouble I was having.  The pos lead to the DNA's input broke off the other day while I was inspecting the connections.  After a closer look, turns out the pos lead was only attached via a few strands of the wire.  I must have done a crappy job when stripping the wire and cut off 75% of the strands on that end...duh.

Anyhow, my new solder sucker came today so back to the bench it goes.

Glad you found it Kott. A few strands would do it. Inducing a voltage drop