The Magic-Flight Box

[scy123]

Very true, 'specsmanship' sells stuff. Peak currents, held for tens of seconds can make for troubles. IMO you should design around typical duty, not max possible even though the LB in basic configuration does just that.

I would have to design my adaptor around low amp rated batteries (for saftey). I tested my muad dib to draw 1.5a at batter. A regular mflb should drawn around 3a. Really lowest quality 18650 is around 3.5a. So should not be a problem with amps. Maybe really shady/old li-ion will be rated at much lower amps..... I can't really be responsible if someone gets something so shady so........

The LB, we're told, was designed to run at 15 Amps, with .75 Volts 'across the rails. The Thevenin (internal) 'source in the NiMH is 1.25 nominally, so have a Volt (1.25 minus .75) is 'lost', mostly to internal resistance (Thevenin again) inside the cell (which is why it heats).

Watts is what dictates power .75v at 15a = 11.25w and more at battery. Mods go upto 300w. 11.25w is peanuts.
None of this actually matters with mods. The mod will send a straight wattage till the battery dies. IE: straight battery will vary the watts based on what the battery can handle at that remaining capacity/Mods will send a straight wattage till the battery dies.

I suggest you think in terms of current supplies, not voltage.

Was thinking in terms of wattage which is the actual power going to the device. you have to take both voltage and amps into consideration which is what watts does.

 

[OF]

Watts is what dictates power .75v at 15a = 11.25w and more at battery. Mods go upto 300w. 11.25w is peanuts.
None of this actually matters with mods. The mod will send a straight wattage till the battery dies. IE: straight battery will vary the watts based on what the battery can handle at that remaining capacity/Mods will send a straight wattage till the battery dies.



Was thinking in terms of wattage which is the actual power going to the device. you have to take both voltage and amps into consideration which is what watts does.

Actually Watts is power, the unit of power in fact.

Designing in terms of Watts has many of the same issues as using Voltage. Changes in resistance (as happens in the SS screen and connections) can goof you up. My advice to design using Current stands. But it is, of course, your call.

Not a simple nut to crack effectively. MF put a lot of serious effort into it and IMO came out with a design of the same caliber as their other designs....well done. Far past 'simple hacks'. Solid Engineering and use of Material Science. Like VM and TV. With varying degrees of 'Manufacturing Engineering' as you might expect. And the predictable conflicts with sales and the market?

Run stuff.

OF

 

[scy123]

Actually Watts is power, the unit of power in fact.

Designing in terms of Watts has many of the same issues as using Voltage. Changes in resistance (as happens in the SS screen and connections) can goof you up.

OF

modern mods continually checks resistance and adjust voltages automatically to the set desired wattage. Don't even know how you're gonna design something with just volts since you don't know the amps and you need to know amps to have proper wiring ect.

The changes in SS is what i'm betting on actually. Changes in ohms = you know what the temp of screen is. Temp probes work cause you have an element at known ohms at that temp..... the MFLB is a large temp probe......

 

[TommyDee]

Yes, the PA is very much like the peek charge of the sub-C's Simple test for me was the fact that going from brown to charred brown using the PA at full power almost always wanted to combust (dry herb, a few black emitters stuck to the screen, and some fresh air - perfect storm). Had the very same issue when using the sub-C at peek power. That cell peek lasted long enough to replicate the PA at full power. Now I only charge the 4200mah sub-C for the entire session. With proper care and patience I can get every last bit of vape from a trench and the cell will be ready for a charge. The 5000mah cell might just give that little extra that this solution could still benefit from. But for now, 5000mah cells are still more than 2x the price.

 

[scy123]

Sorry, I post a lot of details. Most of which is not really much concern for end users. What matters is results.

Muad Dib holding 450f for 14s
https://i.imgur.com/xB0Cyy4.mp4

Graph of the pull.
https://i.imgur.com/wi9D0MD.png

Just a rough test really. I actually had to set temp at 200f, cause I don't know tcr of mflb. You can see I set max wattage at 30w and it regulated iteself at under 2w somehwere, so for sure temp limiting. In the graph you can see it boosted upto 450f and then regulated the rest of the way.

 

[TommyDee]

Me Likee Data I just wish I had the tools to collect it.

At 450 degrees, can you see a faint red glow on the screen when the concentrate is gone?
That is the level the current MF Powerex cells push the Muad Dib screen.

BTW, double your pleasure... install 2 screens >

 

[scy123]

Me Likee Data I just wish I had the tools to collect it.

OMG tell me about it..... tools are the B****

BTW: remembered you like 3d printing too.... Check this thing out. https://www.thingiverse.com/thing:801279

OMG so good.

At 450 degrees, can you see a faint red glow on the screen when the concentrate is gone?
That is the level the current MF Powerex cells push the Muad Dib screen.

No glow. The rating taken with this graph would not match aa cause it's an 18650 being buck converted. So the amp draw at battery would be lower then aa.

Edit: could actually adjust it so screen glows and blows if wanted... it's only using 2w and mods go up to 300w

Edit: sorry forgot to edit post..... and I can't delete this hehehe

 

[TommyDee]

yea that's pretty wild!

I think you two just hit the other reason I wasn't big on mod development on the LB... I really didn't want to blow one up. You can't just drop a new screen in at $5. I can certainly see one serious "oops" away from smoking the LB. I've seen what that means on a new MD screen. Have since learned you can torch MD screens for thorough cleaning. I still get the same ~0.23 ohm reading on the mini volt.

And I do suspect that the timeout in the mods are about thermal management. A means to average the duty cycle of heat-generating components.

 

[scy123]

Yea screen blowing out is a major concern. I don't see why the mflb can't have replaceable screen.

I might actually be able to design something where you can replace mflb screens, but then might as well make my own designs...... maybe will do that later on dunno.

Screens are like pennies though.

BTW: pretty sure when mflb was released li-ion where still in infancy and probably not ready. for market.... probably why mflb was designed around aa

 

[TommyDee]

The screen is sealed in the box. Nothing I'd want to mess with. One of the reasons I still like the launch box - the finest screen of any vape I've gleaned to date and sealed.

 

[scy123]

that's why I am trying to ride the mflb market lol.

It does work really nice. Just battery issues for me.

 

[TommyDee]

Yep Tenery really did fill that void in the generic high drain power packs. Happy to hear of others. But their cells are not sweating the LB in the least. If sub-C isn't enough, they also make D-cell Ni-Mh ...but I had to balance the portability to sheer indulgence.

 

[scy123]

Maybe I can do test for you. If you tell me how you make your stuff. I'll make and run test.

Edit: I actually did plan on sending quite a few of the adapters for beta test. But only to find temp control sweet spot and abuse. If you know temp control lemme know!

 

[TommyDee]

Exactly as you would an AA cell. I get internal resistance readings in the 40 milli-ohm and under on the Opus. And someone kindly reminded me there that this is the max due to the added contact resistance (no sense leads).

I run my trench with duff. Normal grind and shoved through a stainless screen to remove the remaining logs (for ABV condiments). First hit hot and vapee until the contact with the screen is properly scorched. Hold and enjoy the real essence as you are forced to give up hard won vape from your lungs. Clean up the trench to mix up that 1st draw goodness and make sure the screen is clean of 'emitters'. The next draw has already lost the peek charge so lengthy slow draws along with sips between shakes to get a char on the rest of anything green. This is a heavy hit too but a lot more teasing to get contact with the screen. 3, 4, and 5 are whatever you can get. Some of these are hot power draws and sometimes the screen can't keep up. But ponder too long and you will overdo something. Keep the herb from sticking to the screen in order to avoid combustion so you can get some really hot rips or even a continuous draw at a relaxed clip in the right conditions. Getting the business end of the remaining vape is tricky no matter what. This takes a little more heat than before. Once you got it, you know it. If you didn't, your probably putting out a flame. By now there is no duff. There is about 2/3 in volume of what as there when you started with the remainder turned to vape. It doesn't stick to the screen anymore unless it created a carbon bond on scorching. Those stuck blackheads are a sure sign you will risk combustion on the next draw. I can tease out the remaining vape in about 4-5 draws. It actually gets tiring if you hadn't settled down for a full session. Anyway, that is where my sessions settled once I could stop fighting the cells. 30 seconds on those later draws is not unheard of.

 

[scy123]

Exactly as you would an AA cell. I get internal resistance readings in the 40 milli-ohm and under on the Opus. And someone kindly reminded me there that this is the max due to the added contact resistance (no sense leads).

Oh man I post a little to much now. Straight battery I mention varies wattage depending on load and capacity. This is in no way the same as a mod. Mods will send straight wattage till end.

 

[TommyDee]

That is why I am still interested in mods

The MiniVolt only does power, no temp options. It is my sub-ohm meter for the most part.

 

[scy123]

I was actually thinking of doing load testing on nimh vs temp of screen voltage drop and ect.

 

[TommyDee]

Aha... now you've hit my peeve with Ni-Mh. At these draw rates, just draw a linear curve from 1.35V to 0.9V and plug that in at 1.8amp-hours per trench. That's pretty close to what I am experiencing during the usable charge, and reading on recharged cells after a full session from the Opus for capacity.

 

[scy123]

I actually thought the ohm rating was much lower on a regular mflb, was going by the maud dib which I had. Seems the ohms very. But If it's 0,1x Ohms like I suspect. Nihm Shouldn't have problems.

 

[TommyDee]

Its a tough nut to crack these days but once cracked it is pretty darn good shit.

 

[scy123]

I tested out some 55milli ohm aa. It did look quite good. https://i.imgur.com/IJxrJUW.mp4 Sorry past confusion. I actually didn't know how much internal resistance affect battery.

Test are regular eneloop too not high drain. Seems like around 550f. My flir loses alot of accuracy above 250f And the actual screen material might be a lot higher.

Edit: you may need to copy and paste full link for it to work.

Edit: sorry my hands where shaky holding it. It should not vary that much btw.

 

[TommyDee]

This entire study has been about learning the deeper meaning of internal resistance for me.

 

[scy123]

BTW, I don't think a lot of you realize the effects the screen resistance has on the mflb.

The watt pull of the screen dictates the temp. With aa you have a nominal 1.2v. you need 2 variables to get watts (using ohms law). One of the variables is the screen resistance. I actually just use an online calc so don't know formula, but.

0.23Ohm (on maud dib) @ 1.2v (nominal for AA) = 5.22a and 6.26w
0.14Ohm (on previously measured regular mflb ) @1.2v = 8.57a and 10.29w
0.05Ohm @ 1.2v = 24a and 28.8w

That will be amps pulled at battery, screen will be less. Batteries can only handle so much amps before bad things happen. So you can see why I was so concentrated on that. Also, you can see how the temp of the mflb will vary with screen resistance.

Also to get amp ratings from c ratings (the c rating is the mfg continuous discharge rating) You take the Mah rating, divide it by 1000 and multiple the results with the c rating. 4200mah/1000 = 4.2 x 5c = 21a continuous discharge.

 

[OF]

This entire study has been about learning the deeper meaning of internal resistance for me.

Good start for sure. "Circuit Analysis" (sometimes called 'Network Analysis') is critical I think to understanding. It goes way past Ohm's law. Key techniques to explore here are Norton (current) and Thevenin (Voltage) approaches.

The real king here is this fellow Kirchhoff, yet another dead white guy. Norton and Thevenin give us simplified tools to work with. Without their help we're reduced to 'cut and try'. Or what I used to describe to the students as "the Columbus Technique: Stumble on it and claim you got there on purpose"........a traditional technique for sure, but not recommended for understanding and optimum decisions.

And then you need to take it dynamic. For instance, Thevenin says that the source ('battery') should be reduced to the OC voltage (no current draw) and the Rth (Thevenin or internal resistance) in series inside the 'magic box'. This will describe what you can expect from the two available terminals under various conditions (for instance Vth over Rth gives the maximum possible current). You put that defined source (with both factors) in series with your proposed load, not some opinion of what it should be based on numbers from the maker. To this you have to include contact resistances (which change a lot in MFLB sometimes) and the TCR induced changes in screen resistance (SS, like most metals goes up about 1/3 of a % per degree C rise).

Norton takes the current approach, but yields the same answers (as it would have to to be useful?). In fact, Rth and Rn are the same value.

This, TCR, is a key to the success of the box. Since the resistance rises in use, current is automatically throttled back allowing faster heat up without the danger of going too hot. Some similar circuits, like those used by TV intentionally picked heater materials with zero TCR change, useful in the 'thermal core' idea they used where temperatures of the heater were allowed to go to 1200 degrees or so to effectively heat the air (not the load directly).

It fun stuff, but you really need Circuit Analysis skills to wade into it?

https://en.wikipedia.org/wiki/Network_analysis_(electrical_circuits)
https://www.circuitcrush.com/circuit-analysis/
https://www.dummies.com/education/s...ics/circuit-analysis-for-dummies-cheat-sheet/

Best wishes in your endeavors.

OF

 

[scy123]

Think a lot of that is way more then what you need to know with mflb.

tcr between boxes would be all the same between boxes. Only issue is if they changed materials for screen and rails. (notices every box hits the same?) and if can get tcr would be able to tell accurate temp with a mod.