Just trying to understand this better. From what I have been told and what I have understood. Dual 18650's does not mean it doubles your battery life. It just doubles the voltage from 3.7 to 7+ volts? so if I have a regulated mod that is powered by two 2000mah batteries, it is only read as 2000mah and not 4000mah as one might assume.
Comparison: Battery life of dual vs single 18650 regulated mods for Newbies
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Your assumption is correct... you might maintain a usable charge a tiny percentage longer with a dual -vs- single battery unit. But no where near double and not worth the added expense.
It depends on the configuration of the two 18650 batteries.
Parallel - Double the amp limit and mAh capacity, voltage remains the same.
eg. two Sony VTC4 - 60 amps, 4200 mAh, 4.2 volts fully charged.
Series - Double the voltage, the other two values remain the same.
eg. two Sony VTC4 - 30 amps, 2100 mAh, 8.4 volts fully charged.
Parallel - Double the amp limit and mAh capacity, voltage remains the same.
eg. two Sony VTC4 - 60 amps, 4200 mAh, 4.2 volts fully charged.
Series - Double the voltage, the other two values remain the same.
eg. two Sony VTC4 - 30 amps, 2100 mAh, 8.4 volts fully charged.
but it doesn't matter as the watt hours remain the same regardless what setup.
In series
Wh = 2000mah x 8.4/1000. = 16.8 Wh
In parallel
Wh = 4000mah x 4.2/1000 = 16.8 Wh
In series
Wh = 2000mah x 8.4/1000. = 16.8 Wh
In parallel
Wh = 4000mah x 4.2/1000 = 16.8 Wh
WRONG!!!
The equation is Wh = mAh × V / 1000
In series
Wh = 2000mah x 8.4/1000. = 16.8 Wh
In parallel
Wh = 4000mah x 4.2/1000 = 16.8 Wh
Both mods deliver the same watt hour. One does it at double voltage and half the mah, the other does it at half voltage with double the mah, but the end result is the same watt hours on both mods.
There is a difference on how the power is delivered, but there is ZERO difference on actual battery life.
This is why the DNA200 lipos batteries only have 900mah but outlast 2100mah 18650s. The voltage is 11.5V on the lipos, so they have more total watt hours despite having less than half the mah.
The equation is Wh = mAh × V / 1000
In series
Wh = 2000mah x 8.4/1000. = 16.8 Wh
In parallel
Wh = 4000mah x 4.2/1000 = 16.8 Wh
Both mods deliver the same watt hour. One does it at double voltage and half the mah, the other does it at half voltage with double the mah, but the end result is the same watt hours on both mods.
There is a difference on how the power is delivered, but there is ZERO difference on actual battery life.
This is why the DNA200 lipos batteries only have 900mah but outlast 2100mah 18650s. The voltage is 11.5V on the lipos, so they have more total watt hours despite having less than half the mah.
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I got an evic vtc mini, a single cell mod, and a cuboid,, a dual cell mod, at about the same time. Both are made by the same company and the boards have similar features including a puff timer. I did a direct comprison. with the same brand new batteries and used the same rda with the same build and identical settings. The cuboid gave me about the same puff time as the mini. The ony reason I got the cuboid was hoping for more endurance. I didn't get that. The cuboid might be fine if you need high watts but I didn't get the endurance I was looking for. The mini is capable of getting me through almost a full day with no recharging. When I want a cushion I take a spare battery (stored in a silicone sleeve for safety of course). Recently there is a dual cell mod wired in paralell that should give more endurance. I believe eLeaf is making it. I'm not getting that one for now. The mini is getting the job done.
Depends on your tolerance of risk! As a general rule of thumb and for no reason other than my own feeling of safety, i never like to exceed about 75% of a battery's rated CDR.
So 15A in this instance, which means i can power a coil of 0.28Ω safely. (R=V/I)
T
So 15A in this instance, which means i can power a coil of 0.28Ω safely. (R=V/I)
T
I use that battery. My goal is to have a good vape, not see how far I can push a battery before it fails. According to my calculator my 1.25 ohm stainless coil at 30 max watts and 400 degrees max temp is asking for no more than 5 amps. My goal is to see how little power I can use instead of how much I can get away with. When I see mech mods or big clouds these days I think, why isn't that guy wearing safety goggles and a football style mouth guard?
Then you don't know that much about subohm vaping.
I can blow huge clouds with my subtank mini running Ni200 coils at 24 watts. I'm running 20A batteries and drawing a maximum load of just 9.8A. Less than 50% of what the battery is capable of delivering.
Huge clouds does NOT require unsafe vaping practices.
which brings to the topic of how do we know what wattages to run our sub ohm tank at? people always say start low and bring it up to where it satisfies your taste.
do low resistance coils need more wattage and vice versa?
for example if i want to vape at 0.3 ohm, what wattage should i start at?
do low resistance coils need more wattage and vice versa?
for example if i want to vape at 0.3 ohm, what wattage should i start at?
On a regulated mod, what counts is the set watts on the machine. A mod set for 10 watts delivers 10 watts/seconds of power (ignoring efficiency losses) for each second the fire button is pressed. There 3600 watt/seconds in a watt/hour, so a 1 second button push uses .00278 watt/hours; or looked at from the other direction, a mod set for 10 watts will flatten a 1 watt/hour capacity battery in 360 seconds (6 minutes total button on time). If you have 2 x 1 watt/hour batteries, it takes 640 seconds or 12 minutes button time to flatten both of them. This is true regardless of the coil value or the voltage the mod applies to that coil. What counts is the watts setting.
Batteries are rated in mAh for capacity, rather than watt hours. That can be useful, as it tells you what kind of current the battery can support for how long, but it doesn't tell you much about how much power the battery stores in absolute terms. There are a lot of complex technical reasons why this is done, and I won't get deeply into them here, but for one thing, it isn't easy-- actually, it's impossible-- to calculate exactly how many watt/seconds or watt/hours a battery will hold. The closest you can get is a first order approximation; with some battery chemistries, the closest is a second order approximation. That's because how much power you can cram into a battery, and then get that power back out, is dependent on a lot of variables, like temperature, voltage sag under load, I^2R losses during discharge and others, that can do different things at different times. Further, the chemical processes that store and release the electrons are a lot slower than just shooting the electrons down a wire. You can run a battery "flat" with a high current discharge, so it won't make any more power, then let it rest a bit, so it cools down and the internal chemicals have a chance to rebalance their electron distribution, and then get more current out of it. A rough and ready estimate-- if not a particularly accurate one-- of how many watt/hours a battery holds can be found by: (battery mAh) x (battery nominal voltage; usually 3.7) / 1000. This is because amps x volts = watts. Therefore, a 2500 mAh battery holds approximately (2500) x (3.7) = 9250 milliwatt/hours (mWh) or, divide by 1000, 9.25 watt/hours. I stress that's an approximation, and not a particularly accurate one.
On a mechanical mod, things are different. This is because applied watts vary with voltage given the same coil. It's not like setting a regulated to 10 watts and then getting 10 watts out of it. But on a regulated, if you set the watts and leave them in one place, then you get twice the life from two identical batteries than from one because you have twice the power storage.
Batteries are rated in mAh for capacity, rather than watt hours. That can be useful, as it tells you what kind of current the battery can support for how long, but it doesn't tell you much about how much power the battery stores in absolute terms. There are a lot of complex technical reasons why this is done, and I won't get deeply into them here, but for one thing, it isn't easy-- actually, it's impossible-- to calculate exactly how many watt/seconds or watt/hours a battery will hold. The closest you can get is a first order approximation; with some battery chemistries, the closest is a second order approximation. That's because how much power you can cram into a battery, and then get that power back out, is dependent on a lot of variables, like temperature, voltage sag under load, I^2R losses during discharge and others, that can do different things at different times. Further, the chemical processes that store and release the electrons are a lot slower than just shooting the electrons down a wire. You can run a battery "flat" with a high current discharge, so it won't make any more power, then let it rest a bit, so it cools down and the internal chemicals have a chance to rebalance their electron distribution, and then get more current out of it. A rough and ready estimate-- if not a particularly accurate one-- of how many watt/hours a battery holds can be found by: (battery mAh) x (battery nominal voltage; usually 3.7) / 1000. This is because amps x volts = watts. Therefore, a 2500 mAh battery holds approximately (2500) x (3.7) = 9250 milliwatt/hours (mWh) or, divide by 1000, 9.25 watt/hours. I stress that's an approximation, and not a particularly accurate one.
On a mechanical mod, things are different. This is because applied watts vary with voltage given the same coil. It's not like setting a regulated to 10 watts and then getting 10 watts out of it. But on a regulated, if you set the watts and leave them in one place, then you get twice the life from two identical batteries than from one because you have twice the power storage.
I grant your point. Big clouds can be made with moderate power. I follow ecig news. Recently there are too many well documented reports of people hurting themselve with ecig related stuff. All of them are at fault but thats not good enough. The ethic around here should be what's the least amount of power that gets the job done instead of how much power can I get away with.
Now, I'm just confused.
Why wouldn't a regulated dual 18650 last substantially more than a regulated single 18650 mod given everything in the setup is the same?
No where near double? Do you understand there are two types of mods? Series and Parallel mods.....ring a bell?
Series mods use the mAh of one battery but adds the voltage of both batteries.
EX: Samsung 25R 18650 4.2V 2500mAh times 2 gives you in a dual mod only 2500mAh battery but 8.4V
Parallel mods usues mAh from both batteries and voltage of one battery.
EX: Samsung 25R 18650 4.2V 2500mAh times 2 gives you 5000mAh battery but 4.2V
I'm-.. Wh-.. Maybe I'm missing something? Why are you guys talking about regulated mods as if they have static voltages? That's never the case, hence.. "Regulated" mod.
If you usually use 1 battery at 4.2V (regulated) and it lasts 15 minutes of actual "vape time" (time wherein you're pressing down the button) and then you switch to a dual-battery mod (regulated), set at 4.2V also with same coil configuration, it will last 30 minutes of "vape time."
If you're using your series dual-battery mod at double the voltage of your single-battery mod then yeah, you'll see half the vape time, but like.. Why would you double the voltage?
If you usually use 1 battery at 4.2V (regulated) and it lasts 15 minutes of actual "vape time" (time wherein you're pressing down the button) and then you switch to a dual-battery mod (regulated), set at 4.2V also with same coil configuration, it will last 30 minutes of "vape time."
If you're using your series dual-battery mod at double the voltage of your single-battery mod then yeah, you'll see half the vape time, but like.. Why would you double the voltage?
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