Single vs. Multi Battery Mods

Timwis said:
I'm the opposite only would use dual battery indoors and find a single battery device with a fresh battery when leaving the house lasts with ease and with a single 21700 it laughs at a day out. I do of late vape MTL but even when i'm vaping DL around 30-40watts still find a single battery will last no problem. I guess you must vape at higher wattage's because in years i have never took a spare battery out with me and never ran out of battery life and i can vape a lot so i think it's down to what wattage people vape at as surely if there is no need having something more portable is more desirable.
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Bossman won't you do me a big favour.

See your post below and circled part.

I have never heard a 21700 battery laugh before. Next time you go out and pop a battery in it won't you record the laugh it makes and post here.
I'm dying to hear what's a 21700 battery sounds like laughing.
3d533129cf307333a75a1a190bb5f918.jpg


Sent from my LYA-L09 using Tapatalk
 
OOoww those ultrafire's. I have had to stop a couple of people putting them in their mods. I hate being a nanny and gave up trying a long time ago but had to convince a few peeps that what it said on the label was not so. The one bloke told me to pissoff I did not know what I was talking about.

I have not heard from him in a while. :think:
 
Blends Of Distinction said:
Bossman won't you do me a big favour.

See your post below and circled part.

I have never heard a 21700 battery laugh before. Next time you go out and pop a battery in it won't you record the laugh it makes and post here.
I'm dying to hear what's a 21700 battery sounds like laughing.
3d533129cf307333a75a1a190bb5f918.jpg


Sent from my LYA-L09 using Tapatalk
Click to expand...
It's more of a chuckle!
 
Timwis said:
I'm the opposite only would use dual battery indoors and find a single battery device with a fresh battery when leaving the house lasts with ease and with a single 21700 it laughs at a day out. I do of late vape MTL but even when i'm vaping DL around 30-40watts still find a single battery will last no problem. I guess you must vape at higher wattage's because in years i have never took a spare battery out with me and never ran out of battery life and i can vape a lot so i think it's down to what wattage people vape at as surely if there is no need having something more portable is more desirable.
Click to expand...

Yup. It's all about the wattage. I can't last on a single 18650 or 21700 on a long time out of the house.
 
Timwis said:
"As most people seem to vape below 50Watts, (and sub ohm to boot), I question whether dual cell series mods are required, as they certainly don't offer any improvement on battery life given the above example"

I really don't know all the technical stuff and 90% of your post goes straight over my head but the part i have quoted just isn't true as basically every dual 18650 device i have lasts twice as long as a single 18650 and my dual 21700 devices last twice as long as my single 21700 devices.

The way battery life was explained to me between series and parallel was one way it's like both batteries are added together so essentially become one bigger battery and the other way they act as separate batteries so one way the mAh is doubled and the other not but then when you vape the configuration where the mAh isn't doubled you only use half the mAh per battery for the same identical vape at a certain wattage and time duration.

I was given two different maths equations which i can't find which gave the difference between how battery life is worked out between series and parallel and although the two equations were completely different the end battery life as in how it would effect a vaper with a regulated device worked out exactly the same. It was though then explained that there would just be the slightest improvement in battery life and i can't remember if it was in favour of series or parallel because running one way over the other (i can't remember which) was more efficient but we were talking just a couple of %. What i can remember was the efficiency was in favour of the way most think you don't get as good battery life, so essentially they are wrong! But i'm such a muppet i can't remember which was which!
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Firstly my apologies for the protracted replies ... I spent the past week in Durbs, returning earlier this evening after witnessing one helluva accident outside Sir Vape's shop earlier in the week .... anyhoooo ....

Hi Timwis,
I had someone attempt, (unsuccessfully), to explain it to me, and ... sorry to say this ...
Single and Parallel Batteries DO NOT have the same Amp-hour rating, (battery life in this context), if the effective voltage seen by the coil(s), mesh or ceramic pads is below a single cell voltage
I'll gladly demonstrate this practically if required.
It would indeed be true however IF you were to use high resistance coils at high power, (which no one does!), making the argument mute, hence my questioning same.
 
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Stranger said:
Batteries in parallel will increase your amp hours, or size if you will, the voltage will remain the same.

Batteries in series will increase your voltage with the same amp hours.
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Exactly! ... Hence my argument that a single battery would in theory be identical in terms of battery life :)
 
Timwis said:
In theory you have more starting battery life in Parallel but in series the ampage for the same vape is shared between the two batteries (or something like that) any way you basically get through your mAh life at half the rate. Different equations but when it actually comes to how much vape time a vaper gets it's basically the same!
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It cannot be the same!
Simply put; Two or more cells in series would have the same A/hr rating as a single cell, sooooo ... assuming that your coil "sees" a voltage of no more than a single cell, (aka via a regulated mod), then the cell life would be the same irrespective of whether you had one or even twenty cells in series.
 
Timwis said:
In theory you have more starting battery life in Parallel but in series the ampage for the same vape is shared between the two batteries (or something like that) any way you basically get through your mAh life at half the rate. Different equations but when it actually comes to how much vape time a vaper gets it's basically the same!
Click to expand...

In parallel you have a “current divider” setup, which means that if the batteries are equal is capacity, voltage in internal resistance then the total current will be shared equally between the 2 batteries, hence the term a current divider. In a series configuration the total current that passes through both batteries are equal as it cannot be shared or divided. Basically what goes in on the one side of battery 1 comes out on the other end of battery 2. A series configuration is commonly referred to as a voltage divider.

The reason why people tend to think it last longer might not be the case, is subjective and does not follow Kirchoff’s law. Although you still vape at 25w or 50w or whatever, the output voltage to the coil will still remain the same as the coil resistance is fixed. Only if you change the wattage then the voltage will increase or decrease.
 
Intuthu Kagesi said:
Exactly! ... Hence my argument that a single battery would in theory be identical in terms of battery life :)
Click to expand...
So the fact that at the same wattage without fail over the last 6 years (since we really started getting dual battery devices) my dual battery devices between battery swaps last twice as long as my single battery devices without fail is a fiction of my imagination, what ever the theory dual battery devices last twice as long as single battery devices and i go by practice (reality) not theory that doesn't pan out!
 
ThreeFoxVapes said:
In parallel you have a “current divider” setup, which means that if the batteries are equal is capacity, voltage in internal resistance then the total current will be shared equally between the 2 batteries, hence the term a current divider. In a series configuration the total current that passes through both batteries are equal as it cannot be shared or divided. Basically what goes in on the one side of battery 1 comes out on the other end of battery 2. A series configuration is commonly referred to as a voltage divider.

The reason why people tend to think it last longer might not be the case, is subjective and does not follow Kirchoff’s law. Although you still vape at 25w or 50w or whatever, the output voltage to the coil will still remain the same as the coil resistance is fixed. Only if you change the wattage then the voltage will increase or decrease.
Click to expand...

I think the key is the subjectivity ;)
 
Timwis said:
So the fact that at the same wattage without fail over the last 6 years (since we really started getting dual battery devices) my dual battery devices between battery swaps last twice as long as my single battery devices without fail is a fiction of my imagination, what ever the theory dual battery devices last twice as long as single battery devices and i go by practice (reality) not theory that doesn't pan out!
Click to expand...

I would agree with you IF you had a parallel battery mod, however the math, and a practical test doesn't agree with a series mod having even a slight increase in battery life, (subject to the rider that the voltage "seen" by the coil is equal to or less than a single cell voltage)
 
Intuthu Kagesi said:
I would agree with you IF you had a parallel battery mod, however the math, and a practical test doesn't agree with a series mod having even a slight increase in battery life, (subject to the rider that the voltage "seen" by the coil is equal to or less than a single cell voltage)
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Well it's all my dual battery mods last twice as long (i know whether they last twice as long or not as i am the one using them) as my single battery ones and i have got over 200 of each!
 
Timwis said:
Well it's all my dual battery mods last twice as long (i know whether they last twice as long or not as i am the one using them) as my single battery ones and i have got over 200 of each!
Click to expand...

I'm going to have to agree to disagree with you I'm afraid o_O as it's physically impossible ...
Two batteries in series raise the voltage sure, however you aren't using that additional potential difference, as we're discussing sub ohm with coil voltages less than that of a single cell, and ... as the cells are in series, the same current flows through both.
Another name for Voltage is Potential Difference, so placing cells in series raises their POTENTIAL, however the actuality is still that of less than a single cell
 
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Intuthu Kagesi said:
Firstly my apologies for the protracted replies ... I spent the past week in Durbs, returning earlier this evening after witnessing one helluva accident outside Sir Vape's shop earlier in the week .... anyhoooo ....
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I saw footage of this accident. Was horrendous to say the least. Sad that there was a loss of life as well.

On the battery subject - I charge them up. I load into mod. I vape. Batteries get low, I replace.
I find that dual batt devices last me about twice as long when compared to single batt devices at similar wattage. And I like battery wraps, plain, colorful battery wraps. That's about as far as my knowledge goes :D
 
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Timwis said:
So i am not going crazy?
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Then I'm going crazy to...

Took a tank and placed it on my dual battery mod and vaped until mod said low battery and stopped firing. Then swopped the tank to my single battery mod running same ohms and wattage and vaped it till mod said low battery and stopped firing.

I can conclusively say the battery life lasted almost double on the dual battery mod and also the puff counters on each mod confirmed this.


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DougP said:
Then I'm going crazy to...

Took a tank and placed it on my dual battery mod and vaped until mod said low battery and stopped firing. Then swopped the tank to my single battery mod running same ohms and wattage and vaped it till mod said low battery and stopped firing.

I can conclusively say the battery life lasted almost double on the dual battery mod and also the puff counters on each mod confirmed this.


Sent from my LYA-L09 using Tapatalk
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Yeah, it was explained to me once that in series the mAh isn't doubled but the calculation of how wattage uses up the mAh between series and parallel is different and the end result you get the same Watt hour which is what determines vape time!
 
Consider:
A single cell is fully charged at 4.2V. At 3.2V it is fully discharged - that's a voltage drop of 1V.

If we have two cells in series: Fully charged they are at 8.4V and discharged at 6.4V - That's a drop of 2V. It stands to reason that this drop will take twice as long to happen.

In parallel: The voltage is at 4.2V (charged) and 3.2V (discharged), but the current drawn from each cell is halved, so again, twice the time to discharge to 3.2V.

This simplification assumes the same load (coil) and ignores internal resistance so series and parallel circuits won't last exactly the same time, but it will be close.
 
Lets have a look at the circuit below, and assume that the Pulse Width Modulation Circuitry has no losses, and plug in some typical values;

Lets also assume that we are using a 0.5 Ohm heating coil running at say 15 Watts.

This would mean that the current flowing through this coil is equal to the square root of coil power divided by the coil Resistance, (see Formula Wheel Below), or 5.477 Amps.

It also means that the voltage across the coils would be 5.477 Amps / 0.5 Ohms, or 2.738 Volts.

The Pulse Width circuitry would be controlling the voltage, and the current displayed in the ammeter to the left of the circuit, would be identical to the one on the right, as this is a series circuit.

The Voltage displayed on the Voltmeter connected to the battery(ies) however would be displaying a different reading to the voltmeter across the heating coils, as the Pulse Width Modulation Circuitry would be controlling the coil voltage.

As Battery "life" is determined in Amp hours, (ie. how many amps can flow in one hour), and as this is a series circuit, it makes NO DIFFERENCE whether there is one or even 500 batteries connected to it, as the voltage seen by the heating coils would always be constant, and the current flowing through ALL batteries would be the sameMod Circuit.png FormulaWheelElectronics.png
 
Puff the Magic Dragon said:
Watch Mooch's video on series and parallel batteries.

The regulated bit starts from the 10th min but it's worth starting from the beginning.



I prefer using dual battery regulated mods for the battery life. As Mooch explains the two batteries will give you double the life in theory. He explains why this is not always the case.
Click to expand...


I like MOST of what this guy says, however there is a contradiction ...
Battery life is measured in Amp/hours, so a parallel battery mod would increase the life, and a series battery mod, would be the same as a single cell mod PROVIDED the voltage across the coil(s) is lower than the voltage of a single cell ... Which he admits, (check the ringed elements below);

cpacity.png cpacity2.png
 
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