Impact of series resistance... Cheap Mech's...

[Lastlokean]

Resistance exists in the path between your battery and atomizer. Including the connector itself. This issue is larger than commonly discussed.

Ideal situation:



Here you get ohms law: V = I*R In this case we get the ideal 2 amps and 7.2 watts to the load.

Real Life:


This is an example of a cheap flashlight bought from walmart. Between the spring, tube, switch and connector there is approximately .55 ohms of resistance in series with the load.

As a result, the output current is 3.6 V / (1.8 + .55) = 1.1 amps and only 2 watts delivered to the load. (.6 watts on waste)

This is why those cheap aluminum flashlights make poor performing pv's.

The battery itself is a serious source of series resistance... Ignored in these calculations.

Solutions:

1) Highest quality build with very quality materials.
- Minimize series resistance. It will never be 0...
2) Increasing load resistance and voltage.
- Example 7.2 V / (3 Ohms + .55 series) = 2 amps = 6 watts on load (1 watt on waste)
- Minimizes the impact of series resistance.
3) Add load buffering capacitor...


- The capacitor bypasses most of the series resistance. The capacitor will charge to the batteries voltage.
-When the atomizer is fired it will pull current from both the capacitor and the battery. Cutting the effect of series resistance 50%.

- Example discharge:
(hard to read sorry)

In a nut shell this will cause a time delay on the voltage droop. However there would need to be a minimum 30 second pause between vapes.... (biggest downside)

Conclusion:

- Quality builds made with quality materials will perform better.
- Every micro-ohm of series resistance dramatically hurts performance. (springs, contacts switches,LEDs, fuses, circuitry)
- Quality low resistance / low EMR / high drain batteries are a must.
- Helps justify all my expensive apvs...

 

[DrMA]

IMO, the battery's internal resistance (impedance) dwarfs the other system components (tube, button, spring etc.). The smaller batteries in particular (14500 and smaller) can have IR as high as 300mΩ+ when new and it only gets worse with use and age. The only real way to deliver consistent power to the coil is to use a regulator (set up as either VV or VW).

 

[Lastlokean]

Yes the battery commonly has ~300 mohms. However the batteries resistance is in parallel with the load. Not in series. It makes a huge difference on the impact.

Take one of those cheap $1 led flashlights that run off 3xAAA. Take out the 3xAAA holder and hard solder it (copper wire) to a 510 connector. Notice how well the atomizer performs from .5 ohms - 3 ohms.

Then mod the flashlight lens to hold a 510 connector. Run ground through the aluminum tube and hard solder + to + on the 510 connector. Notice how in the first experiment you got huge plooms of vapor? And in this experiment anything under 2 ohms makes no vapor. From 2-3 ohms you get minimal vapor.

Notice how the batteries existed in both of the above examples... I am sure there resistance is not causing the issue.

 

[supertrunker]

Why is it i get the same argument framed in a different way? "Trunker when you were 20, you were like a Duracell or Energiser, but now you are like a tired old solar panel?"

"Must be internal resistance dear - try me with dual coils".

Don't run coils in series, run them parallel and halve the resistance.

T

 

[Lastlokean]

Why is it i get the same argument framed in a different way? "Trunker when you were 20, you were like a Duracell or Energiser, but now you are like a tired old solar panel?"

"Must be internal resistance dear - try me with dual coils".

Don't run coils in series, run them parallel and halve the resistance.

T

... What are you talking about? This thread is talking about a single coil and a single battery in a tube. Primarily it is talking about the loss of energy from the resistance of components... AKA the tube, switch, etc.

All of this stems from working with 3xAAA batteries. I found that they could easily power an atomizer when outside of any box. This was found by hard wiring 3 batteries in series to a 510 connector. (no switches, tubes or anything just 3xAAA and copper wire.) So then I 'modded' a 3xAAA flashlight into an ecig. The resulting device gave off literally 0 vapor.

The resulting conclusion has been that the flashlights various components consume ~33% of the batteries power. Meaning the atomizer got only 66% of the power it got without the switch and tubing. This left implications that a highly conductive (copper, silver, gold) tube mod would provide superior performance.

I don't understand what is so hard to understand about all of this.

Edit: If you notice the post next to this one titles: "How To Get Better Continuity From Your Mechanical" Is exactly the type of thing I am going for. Maximizing power delivery to the load by minimizing waste resistance. Too bad the people ^ half sticks to far up their @$$ to take an unbiased look on the topic.

Edit2: To the first poster... Way to regurgetate unfounded information. NiMh AA/AAA batteries can easily provide up to 10 amps and have an internal resistance of ~.050 Ohms... Short one across your meter if you don't believe me.

 

[Relayer1974]

In a nut shell this will cause a time delay on the voltage droop. However there would need to be a minimum 30 second pause between vapes.... (biggest downside)

Where did you get 30 seconds from?

 

[rolf]

I think the worst offenders are the battery springs ..some one said they are for safety !!take for instance the rattshack aa box wit 4 springs
and mesure the ohms youl be supprised no wonder it wont work as it should and not even close.now I make my own aut of some leaf spring material ..to much pressure ? just dremel a slot in it and bend over now you have two forks to for a low ohms contact..
in my pucks it made a difference like day and nite. and if you want a fuse use one !! some ptc fuses have 0.08 ohms just ohms law .
also using copper straps for wiring a lot .

 

[Lastlokean]

rolf I would agree that springs can be among the worst offenders... Especially in plastic mods that use otherwise copper wiring. Unfortunately pure copper springs don't hold up well over time... The metal is too soft. People have had good luck coating the spring contacts in conductive silver paint. (expensive)

Where did you get 30 seconds from?

I got the 30 seconds as an approximation of an RC time constant that would provide enough power over a 5-10 second vape. Theoretically 2-3 Farads should more than cut it... But in the last two images of my first post are a simulation of a battery charging a 5 F cap and a momentary switch discharging it into a 1.8 ohm simulated atomizer coil.

As you can see in the simulation it took about 30 seconds to charge the capacitor to 90% of the batteries voltage.


Pretty much with this solution you use the resistance of the tubing / spring to charge a super cap that is right next to the 510 connector. (Controlled by the master on/off) Then when you press the momentary switch you are vaping from the capacitor

 

[rolf]

jes on copper ..not to suetable for springs . my springs are steel plated ..thy have two forks each about one 8th wide ...and only about one halv inches long ..the ohms reading is 0 with my meter . but sure can mesure a good amount on springs from a radio shack case .
rolf

 

[ZeroDisorder]

Yes the battery commonly has ~300 mohms. However the batteries resistance is in parallel with the load. Not in series. It makes a huge difference on the impact.

How are you able to say that the internal resistance of the battery is in parallel with the load? What we're talking about is ESR (Equivalent Series Resistance) of the battery. Modeling these batteries on a short time scale under a normal load should be done with a Thevenin transformation, meaning you'll essentially have a Vsource of ~4V with a resistor in series equivalent to the ESR of the battery, then have all of the rest of your resistances in series after your ESR. There is no parallel loading anywhere, except in the condition of a deck shorted wick or something similar to the sort. If you have any other parallel loading that isn't contributed by your atomizer you'll have a constant battery discharge. These batteries do have a very small internal leakage current, but it is not significant enough to model when doing a short term analysis.

Edit: Also, the capacitor idea is just not seriously feasible between its ESR vs its size. Though, to decrease your "30 second between vapes" you could just lower your charging resistor's value. That should also indicate how much energy is required to fire and use an atomizer vs the amount of energy stored in your capacitor. Specifically the difference in voltage of your capacitor vs your dropped battery voltage. .5*C*Vf^2-.5*C*Vo^2, since voltage differential is rather small, you won't have much energy able to discharge across your load.