Tinkering with the OKL2-T20 20A 110W dc/dc converter...

[Claviger]

I would suggest 4.5x2.5x1 ish boxes. Hammond 1590B series is in that ballpark. It will still be a tight fit, but give enough room to get a box in for batteries.

digikey, mouser, amazon all have them.

The other route would be fastech using one of these for cheap as chips nice aluminum boxes:

1 x 100*76*35mm Aluminum External Enclosure Case for Electronics DIY black
1 x 100*66*43mm Aluminum External Enclosure Case for Electronics DIY black
1 x 100*76*35mm Aluminum External Enclosure Case for Electronics DIY gold

[deleon209]

Thanks I've ordered a few boxes before I finally found out what was the right size. Now I gotta order another one and wait. This will be my first boxmod then I got 5 raptors waiting so I'll build this one then move onto those.

[deleon209]

I got some fatdaddy vapes mod Connector 510 but I got a graveyard of parts so I have some topcaps for a hammer Chi you nemesis and I wanted to know if I could just use those and solder to it like I would a reg 510??? I'd rather use a copper contact one then a basic 510.

[Claviger]

You absolutely can use them. Just look up how to solder to steel if they are steel to ensure a good contact.

[JUICYOHMS]

Very Nice...I'm getting ready to build a Box mod using this chip, but would like to use the same pot & knob the the AXIS box mod uses...Does anyone know which kind it is or have a part number handy for that particular POT/KNOB setup...
Thanks in advance for any help & these diagrams are very helpful.

[Jasen]

Juicy, the fire switch on the axis mod just looks like a anti vandal switch. The POT knob may just be just that, a knob that might fit any number of POT's.

[Claviger]

Juicy - I used these on my OKL2.  Used a 2.2k ohm pot and 1.43k resistor for the circuit, gives right around 2.5 - 5.6 volt control. Looks very similar to the Axiz mod pot, works great, fantastic quality, will be using them in all box modes that I make in the future, both for my own and for others!!

Yes they are pricey.

http://www.digikey.com/product-search/en?v=716&FV=fff40004%2Cfff80335&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25

Parts list for my 20amp mod:
http://www.digikey.com/product-detail/en/P16NP222MAB15/P16NP-2.2K-ND/1587862
https://www.fasttech.com/p/1258801
http://www.fatdaddyvapes.com/shop.html (The new one with 22mm washer)
Radio Shack switch
1.43k resistor
4x22u caps (2 input, 2 output)
20 gauge
On/Off slide switch

No screen, no reverse polarity protection, no voltage cut.  Some of the better modders may be able to fit it in that box, but I could not. Great mod for myself, but wouldn't give to anyone else.

What amazes me, is that at 3.7 volts my Kayfun hits easily as hard as it does off a Penny Mod (pure copper mech with the lowest recorded drop) using a fresh charged VTC-5!  In fact, the only tank I have that can consistently wick fast enough over 4 volts is my Expromizer.  .69 and .74 ohm builds respectively.  VV mods have now replaced all my mechanicals! 

After typing the above I decided to try my Stillare at .28 ohms dialed up to 5.5 volts........ really bad idea

[deleon209]

Check out the XXIX 29 mod by BCV 18650 no voltage drop at all.
What amazes me, is that at 3.7 volts my Kayfun hits easily as hard as it does off a Penny Mod (pure copper mech with the lowest recorded drop)

I love that hot hot vape! Deserty flavors though a hot fruit vape isnt tasty
After typing the above I decided to try my Stillare at .28 ohms dialed up to 5.5 volts........ really bad idea

Check out the XXIX 29 mod by BCV 18650 no voltage drop at all and I love that hot hot vape! Deserty flavors though a hot fruit vape isnt tasty 

[JUICYOHMS]

AWESOME GUYS...MUCH APPRECIATED FOR THE DETAILED & QUICK RESPONSES...:-)
\M/
Sincerely...
JU-C

[mamu]

I revised the OKL2-T20 wiring guide to more of a schematic type and already I get a request to bring the old one back lol.

I don't like the huge Hammond cases, so I used my Sam case (2x C battery box - 83mm x 57mm x 30mm) and it's fully loaded with P-FET, fuses, low battery indicator, voltage reader, Keystone contacts, fatdaddyvapes new 510 connector, etc. 

The OKR board and wiring would have fit much easier in Sam - Raptor maybe - but with some creative packing and wiring, I got the OKL2 to fit - just barely.

What I've noticed most about this OKL2-T20 is that the batts last forevah between charges!!  Much much longer than vaping same voltage, same coil, as with my Raptor and my OKR mods. 

After the funky start I got with the breadboarded feedback loop, it's turned out to be quite a champ in the vape dept.

This is called space management ...


I sanded then swirlified the case using a 1" mandrel and scotch brite pads on the drill press...


More hand friendly for me than the big Hammond cases...

[JUICYOHMS]

Question about the chip description on MOUSER. They offer this in a Neg Pol Seq  &   Pos Pol Seq....As MAMU stated the Neg Pol Seq was used for this design.
But Does someone know which would be more preferred, what the difference is and could you use either if stock gets low on one or the other?
Thanks again...
\M/

[Claviger]

Neg/Pos doesnt change much except the ON/OFF switch wiring.  The details on it are in the datasheet if I recall correctly, it's not a huge change.

[Claviger]

Not much of a Hammond box fan myself already. They have a somewhat awkward H/W/D ratio for me. Plenty of other boxes out there that feel better in the hand!

[Breaktru]

Nice Claviger. Thanks for sharing

[deleon209]

Nice box kinda reminds me the size of my DPM box I had. I'm thinking of using the Hana mod clones box. Only one battery tho but it's Prewired with battery contacts and 510 ready to go.  There about $20ea but I gotta buy $200 worth so idk maybe if more people want I will get some. Only thing is only 1 battery

[mamu]

I keep dreaming some day we'll have a teeny tiny OLED like the DNA that displays watts, ohms, volts, batt status, and it's already programmed for use and we just hook it up with our buck converter.  We'd be able to have the works and in a smaller case.  The demand for that would be huge.

I kept dreaming of a quality ss never fail 510 connector and at what I could afford and that came true, so who knows. 

[mamu]

Well, so much for having put a low battery indicator in Sam.  I placed the LED above the fire button so I would be sure to see it when it lights and hadn't had a problem with seeing it when it lights, but this time I wasn't paying attention to it or checking the voltage reader was kinda chain vaping and saw the red LED too late - neg batt = 2.6v, pos batt = 3.1v.  ugh.  That neg batt really takes a beating when input volts is low.

On a bright note - I got THIS today to tinker with - programmable UVLO.  sweet!

and tiny footprint for a 16A 88W module...

[Claviger]

Brilliant find!  Allows reduction in component count off the PCB

That data sheet on it is incredibly thorough, even for TI!  Definitely building this one!

[CraigHB]

Nice looking part.  TI always makes the good stuff.  I'm waiting on a 4 switch buck-boost controller they're supposed to be releasing soon.

TI always publishes really nice data sheets.  Them and Microchip always publish the best ones.  My two favorite component makers are TI and Microchip because they make stuff that works well, but also because they have really good data sheets.

[CraigHB]

I keep dreaming some day we'll have a teeny tiny OLED like the DNA that displays watts, ohms, volts, batt status, and it's already programmed for use and we just hook it up with our buck converter.

The thing is the components you need for a gauge set are going to cover what you need for a whole controller board.  Just add a digital pot and develop the MCU program, you're good to go.  So, if anything, you would possibly see complete controller boards that utilize a power module like that one.  People are making them already, but they're selling the whole mod, not the board a la carte. 

It's possible you might see a gauge set like that from a hobby supply, but they tend not to miniaturize things the way you need for an e-cig.

[mamu]

Nice looking part.  TI always makes the good stuff.  I'm waiting on a 4 switch buck-boost controller they're supposed to be releasing soon.

TI always publishes really nice data sheets.  Them and Microchip always publish the best ones.  My two favorite component makers are TI and Microchip because they make stuff that works well, but also because they have really good data sheets.

The datasheet for this converter is awesome - I've read through it at least 6x now to make sure I didn't miss anything and think I've got it figured out. 

I emailed TI tech support with a few questions and am waiting to hear back.

Although it has programmable UVLO (I'm setting it at 6.4v and testing with that), I don't know if there is something onboard that also stops idle current drain after that low volt cutoff. 

The datasheet took me back to the days when working with TI's PTR08100 converter - almost word for word with the inhibit pin.  I never used the inhibit pin with that converter though.  I wonder if anyone used that inhibit pin and with an N-FET to control it like the datasheet suggests or if an N-FET is really required.  The OKL2-T20 datasheet suggests an N-FET to control inhibit but I'm not using one and the converter is working aok.  I don't know enough about N-FETs controlling the inhibit pin though to say what the difference is with and without using one.

I did buy the suggested BSS138 though and it is soooooo teeny tiny and not doable, but I think I found a compatible one in a TO-92 package - ZVNL110A

This is the way I did the schematic for the N-FET:
Drain to inhibit pin
Source to ground
Gate to fire switch
Fire switch to ground

I haven't tested it yet though to see if that is correct.

[Visus]

Its a still drawing mamu

"When the Inhibit control
is active, the input current drawn by the regulator is significantly reduced."

Substantial:
"The hysteresis voltage, which is the difference
between the ON and OFF threshold voltages, is set at 500 mV"

[Visus]

It reads to me as tho you can use it as on/off  or uvlo and not as both. 

time to breakout board a supervisory if using the inhibit.  woot

[CraigHB]

The enginners might give you some crap if you tell them you're using a mechanical pot with one.  The intent with the power modules is to fix the voltage with a normal resistor.  They don't design them for use with a variable resistor in mind, though there's never a problem when you do it.  The engineers still don't like it.

The part is still going to draw some current when disabled by the UVLO.  You'll have to measure it when you get one on the bench, shouldn't be so much that it will over-discharge the battery before you can attend to it.  The spec might be in the data sheet and it may be liberal.  You might find it draws less than specified when you actually measure it.

Concern about idle draw depends on how you fire the atomizer.  If using a switch on the main supply, the point is moot.  If using a tactile on the inhibit pin, idle draws becomes a consideration and possibly a problem.  If draw is under a mA, you're probably fine.  Consider a battery has at least a few mAh left when flagged so a draw of 1mA will give you a few hours to change out the battery before an over-discharge occurs.  If you get draw down to 100uA, then you have a couple days to change out a battery.

I didn't read the data sheet, but I expect the transistor performs the same function as a switch.  Though what the transistor does is mitigate the voltage bouncing that occurs when switch contacts make and break.  It may or may not be a problem for the regulator's logic circuits, but if it is, you can debounce the switch with a couple resistors and a capacitor.  Probably the same number of parts either way.  I would just go ahead and try a tactile there without any debouncing.  If it works without issue, it works.

[Visus]

Craig it states do not use a pull up to debounce probably because it is dual use its either inhibit or UVLo pin.

It also had 500mv is always on if using the inhibit pin to help with soft start-up regardless if uvlo is active or not,  it didn't have the amperage listed..

So breaking vi would be my way of wiring using uvlo, so when she wont fire I know take out the batts but with using vi they are not being drawn anyway .. 


great find by Mamu I searched and searched, no other boards have a programmable uvlo in a package size we can use..

[mamu]

Thanks guys!

lol at the engineers getting cranky.  I won't tell them I'm using a POT then. 

I'm going to try if first with just a push button switch then and see what's what.  Thanks for the explanation, Craig!

I was so hoping there was something onboard that would shut off the idle current drain after cutoff.  My logical self knew it, but my I really want this self is in denial lol.

A modder at ECF has a lipo mod with the Raptor.  He went on a 2 week vacation without the mod and came back to find the lipo batts drained and toast.  So a master kill switch is def needed with mods that use the inhibit and have lipo batts.

Visus - it's both inhibit and UVLO.  Read the datasheet p.8 Terminal Functions - Inhibit and UVLO.

When it says don't use a pull-up, it's talking about not using an external pull-up resistor as there's already an internal one.

[Visus]

Thanks Mamu just rambling trying to see with post if this all is making sense to me
nope
I was thinking also just throw in a nc tact sw using uvlo @8.5v shutdown as off/on
then Craig explained the switch debouncing and my brain exploded lol

Found standby current draw
Input standby current Inhibit (pin 11) to GND, Track (pin 10) open 5 mA
then when uvlo active
Input low current (IIL ), Pin 11 to GND -235 µA

[Claviger]

So about the OKL2-T20.

After having it for awhile I have tried a few different matched sets of batteries with varying results, figured I would post them here. All batteries were bought in pairs and have been used on a rotational basis for the past 2 months keeping them fairly even in discharge/charge counts.  All the tanks I use I am also testing using apples to apples setups at .69 ohms single coil using 26 gauge kanthal a1, so the load is constant regardless of what i vape from.

2 x Sony VTC 5 2600 mah - Last two full days. I pull them and charge them every other night.  All three times I have done so, they have come out at exactly the same voltage. Usually they are around 3.4 volts each when pulled the second evening.

2 x AW 1600 mah - Have only used these once as they do not discharge evenly. From a full 4.21 charge they lasted me only about 8 hours and discharged at an alarmingly different rate. Once came out at 3.32 volts the other went down to 2.28! I did not expect them to die so quickly, and only pulled them when I noticed a change in the vape (sounded wierd).

2 x MNKE 1500 mah - Lasted about 10 minutes, had issues with the load. Didn't bother checking voltages as they did not function properly and went straight back to my wifes "approved for Volcano Lava Tube use only" stack.

[CraigHB]

A modder at ECF has a lipo mod with the Raptor.  He went on a 2 week vacation without the mod and came back to find the lipo batts drained and toast.  So a master kill switch is def needed with mods that use the inhibit and have lipo batts.

Using a main power switch to fire the atomizer does simplify things, but then you're limited to a high power switch.  When using a regulator's enable/disable pin, there's always the idle draw you have to consider and it can be a real PITA to deal with.  It can be a source of issue if using a permanently mounted battery or if you simply don't want to remove batteries when the mod is not in use.

When they design these regulator modules, the intent for the enable pin is only to control the standby/shutdown function of the regulator.  There's not always a lot of consideration put into how much power is consumed when the regulator is not active.  Mostly these parts are used for devices running off utility power, not batteries.  Some regulators will drop current demand into the micro-Amps when in standby or shutdown, others into the milli-Amps.

They usually list current demands in various regulator states, let me see if I can find it for that part in the data sheet.  Okay, taking a quick look at the specs it looks like the standby current draw is 5mA.  Looks like what they've done is sacrificed a shutdown mode for the UVLO function on that inhibit pin.  So, that's going to be high for a discharged battery, but again, you should measure on the bench.  Sometimes those specs are liberal.

To resolve idle draw issues, you can use a main power switch to fire the atomizer and only use the inhibit pin for the UVLO.  You can always use a MOSFET and tactile if there's a problem in using a high power switch.  For a MOSFET switch, there's virtually zero current draw in the off state.  Well there is a little, but it's so small you can consider it zero.

[Visus]

woot
I hit it on the nail, it says what you stated earlier about uvlo current draw probably being very low demand when uvlo is active
it has high mid and low current states listed

Input low current (IIL ), Pin 11 to GND -235 µA


when taking state license relaying data sheet and code are huge part of test
super fun when someone ask or need quest work on hopefully right when posting but your here to clear the way

i need to put page number  but never look at it , just scroll scroll oh there it is lol

[strugelabs]

Will these 1.43k ohm resistors work instead of the ones mamu recommends/uses? http://in.mouser.com/ProductDetail/Vishay-Dale/RN55D1431FB14/?qs=sGAEpiMZZMukHu%252bjC5l7YYphdDAKSU4lHek%2fL%252berSWY%3d
They are out of stock everywhere for the ones mamu has used. :/

[mamu]

Nice find , strugelabs.  The resistor is good to go.

[mamu]

I started a thread for this new converter: PTH08T221W - 16A 88W w/ UVLO...

I didn't realize until breadboarding and seeing how it has to be configured with an NC switch that it might be a big pita just to get programmable UVLO. *sigh*

[strugelabs]

Great to hear! Also what does the amperage of the button mean? Do i need a higher amperage button for more watts my mod pushes out? Or does that have nothing to do with it whatsoever? 

[deleon209]

ok so i put mine altogether and when i hit the master switch it gets so hot it melts the solder off the mosfet connection?? any ideas??

[CraigHB]

That's no deal.  You have a wiring error somewhere causing a short circuit.  Could be a failed or defective component, but more likely a wiring error.  You should probably replace that transistor.  When one melts the solder on the pins it's due to excessive current flow.  Likely the temperature of the junctions inside exceeded tolerance and it's a dead solider now.

[MumsVapes]

I'm new to all of this and thank you Mamu and all the rest of you guys for the pointers and tips on this topic. I've wired up the chip with all your guys recommended parts and it's working good from3.3-5.5 volts. My question is under a load of .42 ohms I'm seeing about a 1 volt drop when firing. I expect some voltage drop but a 1+volts? On my mechanical mod it is no where close to Half that. My question is is there something I can do in order to correct this? And what should I use? Thanks for all your knowledge

[deleon209]

Here's my pics. Well after forgetting a certain sense wore I got the volt meter to display the battery voltage but it keeps refreshing and showing the voltage??? But now I can't get it to fire and show the output volts maybe the fire switch it's bad?
http://imgur.com/a/JWjxE

[Breaktru]

I couldn't tell you if there was a wiring error judging from the photos but the 1S6S DM that you are using pulses. It pulses for readings for 6 batteries and a total voltage of all batteries. I stopped using those 1S6S a long time ago. There are much better DM's available like THIS

[Claviger]

I'm new to all of this and thank you Mamu and all the rest of you guys for the pointers and tips on this topic. I've wired up the chip with all your guys recommended parts and it's working good from3.3-5.5 volts. My question is under a load of .42 ohms I'm seeing about a 1 volt drop when firing. I expect some voltage drop but a 1+volts? On my mechanical mod it is no where close to Half that. My question is is there something I can do in order to correct this? And what should I use? Thanks for all your knowledge

Only thing I can think of that your batteries are getting heavily loaded and they are sagging so low that the output of the OKL drops to maintain the 2 volt difference between input and output.  What batteries are you using and what voltage is the output set at?

[strugelabs]

Breaktru have you ever used the drok volt meters? its the one i ordered. Ill post a link below.

http://www.amazon.com/DROK-Surface-Digital-Voltmeter-Detector/dp/B00C58QIOM/ref=pd_sim_sbs_e_9?ie=UTF8&refRID=1MVG7GQJR40DF8VAYKJT

[deleon209]

Thanks now I know not to use those. And everything I used was from mamus list of parts so nothing different.

[Breaktru]

Thanks now I know not to use those. And everything I used was from mamus list of parts so nothing different.

It's not they are bad meters, just irritating

[Breaktru]

Breaktru have you ever used the drok volt meters? its the one i ordered. Ill post a link below.

http://www.amazon.com/DROK-Surface-Digital-Voltmeter-Detector/dp/B00C58QIOM/ref=pd_sim_sbs_e_9?ie=UTF8&refRID=1MVG7GQJR40DF8VAYKJT

I can't say I used that exact meter but have used similar 3-wire meters. Just know that they need a power souce. Black to negative, white or green to voltage being read (output) and red to battery positive

[deleon209]

i removed capacitors works fine now...is that really that bad to run that way???

[mamu]

i removed capacitors works fine now...is that really that bad to run that way???

Are you referring to the voltmeter as being bad to run that way?  There's nothing "bad" about the voltmeter pulsing, it's just the way that voltmeter works and has been used in hundreds of mods over these last years as that's all we had.  But the new voltmeters are preferred nowadays for the smaller size and steady on display. I really hadn't payed attention to them as I have a stash of the 1S-6S.  But I need to update my guide to just say "Voltmeter". 

If you're referring to the caps as being bad to run that way - it's good that you took them out so not to cause any more damage to the electronics.  Your picture shows the caps wired in series, well not really since you have nothing wired on either end but only where they connect in the center. 

The caps are suppose to be wired in parallel like you did with the fuses.

[deleon209]

@mamu
I was referring to the input/output caps after I removed it fires fine now. But after what you said from the pic it's probably because I didn't do them right. I was Confused on how to do them parallel and solder properly. Do you have a pic of how the capacitors look wires for the input and output? The 4x ones in parallel really threw me off.    that and the wiring for them I'm a Lil confused about to. I tried to look at your pics to see exactly but the schematic changes the way it's ran and the old one makes it look like it's separate from the connection. When I get home from work I'll post a pic to show you what I mean.
Thanks everyone for the help on here I appreciate it.
My first box tho I went for this one first before a okr. Now that I got the hang of it somewhat I'm gonna start making one of each type possible to really master this.

A few questions to.
Go with the black panel or clear to see the LCD ??


http://imgur.com/beCFLnQ

[deleon209]

@mamu
I meant was it bad to run it without the capacitors not the 1s-6s. It's fine that it pulses I got used to it. For some reason though I can't get I  to display the output voltage when I fire it. It works but it doesn't.

[CraigHB]

Caps are opposite of resistors, they subtract in series and add in parallel.  So putting them in series would make them less effective.

In any case, input and output caps are optional for the OKL, it already carries them on the board.  You can run additional ones or not.  Too much capacitance on output can impact regulator performance.  There is a limit and it's specified in the data sheet.  For low ESR caps like the ceramic ones, it's only 1000uF if you look under capacitive loading in the data sheet.  Input is less sensitive to additional capacitance than output, but I wouldn't go overboard there either.

I would probably not run additional caps if they are not required.  No sense adding to the part count and expense if you don't have to.  In doing my own PCB designs, it's not unusual for me to alter the design when possible to eliminate a part here or there.  Part counts always add up fast.

My general attitude is never add parts if you don't have to.  The more simple a design and the fewer parts it requires the better.  That's not to say you should eliminate parts if you have a need for them.  Additional output and input capacitance can be a benefit, but t's not possible to say how much without some bench testing.

[deleon209]

I know parts start adding up fast $$$ I lost track of all the stuff I ordered and it was $300. I got plenty of parts but just saying if I could knock that down a Lil why not