Page 1 of 2 12 LastLast
Results 1 to 10 of 19
Like Tree5Likes

Thread: Battery life

  1. #1
    AVF Regular
    Join Date
    Jun 2016
    Location
    South Australia
    Posts
    701

    Battery life

    Hi AVF.

    Just wondering whether battery life is affected when using dual or single coils.
    Both builds are at the same resistance. One is a dual coil, the other a single, both built to 0.3 ohms.
    Would the battery life/consumption be the same for both as the resistance is the same?
    Thank you in advance.

  2. #2
    AVF Regular
    Join Date
    Apr 2013
    Location
    Toowoomba (West)
    Posts
    7,897
    Quote Originally Posted by maxsmd View Post
    Hi AVF.

    Just wondering whether battery life is affected when using dual or single coils.
    Both builds are at the same resistance. One is a dual coil, the other a single, both built to 0.3 ohms.
    Would the battery life/consumption be the same for both as the resistance is the same?
    Thank you in advance.
    It's tied to the watts you are running. The true capacity of the battery should be measured in watt/hours (W/h). mAh is just easier for the GP to get their head around but it's misleading.

    eg, you have a three battery mod, and you are using 2000mAh batteries. Each battery would actually have a capacity of 7.5 W/h (3.75x2) giving a total capacity for the three batteries of 22.5 W/h.

    If you are running the coils at 100 watts thats 0.225 hours of runtime (22.5/100) or 13.5 minutes actual button on time.

    The batteries in a regulated mod only care about the watts you are running; the mod looks after how that is achieved depending on the resistance of the coil, or coils as the case may be.

    Subtract some run time for the inefficiency of the mod, usually around 5% or more.
    disley likes this.
    Chris: Tobacco free since 17:00 15th March 2013.

  3. #3
    AVF Regular
    Join Date
    Jun 2016
    Location
    South Australia
    Posts
    701
    Quote Originally Posted by fabricator4 View Post
    It's tied to the watts you are running. The true capacity of the battery should be measured in watt/hours (W/h). mAh is just easier for the GP to get their head around but it's misleading.

    eg, you have a three battery mod, and you are using 2000mAh batteries. Each battery would actually have a capacity of 7.5 W/h (3.75x2) giving a total capacity for the three batteries of 22.5 W/h.

    If you are running the coils at 100 watts thats 0.225 hours of runtime (22.5/100) or 13.5 minutes actual button on time.

    The batteries in a regulated mod only care about the watts you are running; the mod looks after how that is achieved depending on the resistance of the coil, or coils as the case may be.

    Subtract some run time for the inefficiency of the mod, usually around 5% or more.
    Thanks Fab.. Sorry for making you type for ages.
    Forgot to mention that i'm running it in a single battery mech.

  4. #4
    AVF Regular
    Join Date
    Oct 2016
    Location
    Backwater Japan.
    Posts
    660
    Quote Originally Posted by maxsmd View Post
    Thanks Fab.. Sorry for making you type for ages.
    Forgot to mention that i'm running it in a single battery mech.
    And you know, he's dumbed it down significantly as well...

    What it says on the label is not what you actually get, unless you run the battery in the same way it was tested at and how the manufacturer promises (!) to deliver those maH to you through their battery.

    Kind of like fuel economy ratings. Under test, the car will do what it says on the label. In normal conditions, good luck with that.

    (That said, I regularly get what Nissan says I should. I don't know how they manage that because I don't drive like a pansy...)

    Basically start with what the battery will deliver, watt/hour is the best 'real' measure for this, but keep the maH in mind because that's important too.

    Deduct 5% or more for the mod inefficiency as Fab says, but also reduce the available power (w/H) the more power/time you pull out of the battery. A mod running at 5w will give maybe 90% of the battery capacity, but a mod running at 50w might only give you 60% of the capacity. This is largely to do with a new fangled thing called 'c rate' which is basically the maH x 1000 (because it's milliamp/Hour, and we want ampere/Hour), and this is 1C. Faster charging reduces the capacity somewhat, because the power gets shoved in there hard and the battery doesn't like it. Higher discharge also upsets the battery and causes heat, which causes higher resistance, which adds more heat, etc, etc.

    In short, the harder you run the battery, the less juice it's going to give you. A battery made to run harder is going to offer up less power, but it's going to deliver more power when run hard than a higher capacity battery that's less able to deliver higher power.

    Multiple batteries reduce the overall load per battery. Basically you've got a higher c rate because the power is taken a little off each battery rather than all of it out of one battery.

    To give you an example that might help;

    Mod A has a 2000maH battery with a 20C max discharge rating. This means it's happy delivering 20(c) x 2(000maH), or 40A. 3.7nominal volts and it'll give you a maximum power of 148w. Run at 50w, you lose 5% in the mod and it'll give you maybe 70% of it's rating at that power level. 65% of it's total w/H means it'll really give you 4.8w/H from the label's 7.4w/H

    Mod B has a 3000maH battery with a 10C discharge rating. This means it'll give you 10(c) x 3(000maH), 30A. 3.7v x 30 = 111w. Run at 50w you lose 5% in the mod, but at that power level it'll only give you 50% of it's capacity. 5% in the mod, 50% in the battery means you will only get 4.9w/H from the label's 11.1w/H

    Note Mod B has a battery that on paper is 50% bigger, but only gives you 2% more button 'on' time. At 50w, Mod A will give you 5:45 of button on time, Mod B will give you 5:53 of button on time @ 50W. 8 seconds more, or a puff or two. That's it. You'll actually get more time than this because you don't run your mod constantly for 5 minutes, but chain-vaping will get closer to this time than taking a puff every couple minutes. The longer between puffs, the more recovery time the battery has which is great news for lower C rate batteries. Keep that in mind as well.

    Mod B loses more power through heat and cell inefficiency, and that battery will have a much shortened service life compared to Mod A. You might only get 300-400 cycles from Mod B, which means a new battery in a year, whereas Mod A is run less hard, isn't giving up much in actual 'button push time' and might get through 700-1000 cycles, so will last 2-3 years if you charge it once a day. Mod B being run so hard might also prematurely fail, and the chances of this are higher because it's being pushed so hard. 'Might' as in 1/1000 chance, maybe. And it might not be a 'stops working', it might be a 'Galaxy Note' type failure...

    I don't know much about these lithium batteries as I do about Nicad and NiMH, but that c rate thing is a largely lithium battery term because they do have real limits to them, and going beyond them hurts the batteries. Lithium batteries are super popular now because they pack a lot of energy into a relatively lightweight package, and give a reasonable, usable amount of power output in the bargain. Use them well and appropriately and they're great. Push them too hard and they don't work too well. Simply put, if you're pulling a lot of watts on your mod, use a battery made to give up that power (look for a higher C rate). If you want a modest number of watts and more button time, look for an appropriate and more modest c rating with more capacity (maH).

    Once you get your head around the relationship between capacity, watt/H and c rate, these batteries don't hold many secrets from you.

    And also know this is simplified and there's even more to it that I've written and my numbers are not to be taken as truth, only examples of how these things work.

    Also make sure you buy good, genuine and reliable batteries because if it's a knock off or cheapo junk, none of the above applies.

    Stu.
    chewbacca likes this.

  5. #5
    AVF Regular
    Join Date
    Jun 2016
    Location
    South Australia
    Posts
    701
    Quote Originally Posted by Schtoo View Post
    And you know, he's dumbed it down significantly as well...

    What it says on the label is not what you actually get, unless you run the battery in the same way it was tested at and how the manufacturer promises (!) to deliver those maH to you through their battery.

    Kind of like fuel economy ratings. Under test, the car will do what it says on the label. In normal conditions, good luck with that.

    (That said, I regularly get what Nissan says I should. I don't know how they manage that because I don't drive like a pansy...)

    Basically start with what the battery will deliver, watt/hour is the best 'real' measure for this, but keep the maH in mind because that's important too.

    Deduct 5% or more for the mod inefficiency as Fab says, but also reduce the available power (w/H) the more power/time you pull out of the battery. A mod running at 5w will give maybe 90% of the battery capacity, but a mod running at 50w might only give you 60% of the capacity. This is largely to do with a new fangled thing called 'c rate' which is basically the maH x 1000 (because it's milliamp/Hour, and we want ampere/Hour), and this is 1C. Faster charging reduces the capacity somewhat, because the power gets shoved in there hard and the battery doesn't like it. Higher discharge also upsets the battery and causes heat, which causes higher resistance, which adds more heat, etc, etc.

    In short, the harder you run the battery, the less juice it's going to give you. A battery made to run harder is going to offer up less power, but it's going to deliver more power when run hard than a higher capacity battery that's less able to deliver higher power.

    Multiple batteries reduce the overall load per battery. Basically you've got a higher c rate because the power is taken a little off each battery rather than all of it out of one battery.

    To give you an example that might help;

    Mod A has a 2000maH battery with a 20C max discharge rating. This means it's happy delivering 20(c) x 2(000maH), or 40A. 3.7nominal volts and it'll give you a maximum power of 148w. Run at 50w, you lose 5% in the mod and it'll give you maybe 70% of it's rating at that power level. 65% of it's total w/H means it'll really give you 4.8w/H from the label's 7.4w/H

    Mod B has a 3000maH battery with a 10C discharge rating. This means it'll give you 10(c) x 3(000maH), 30A. 3.7v x 30 = 111w. Run at 50w you lose 5% in the mod, but at that power level it'll only give you 50% of it's capacity. 5% in the mod, 50% in the battery means you will only get 4.9w/H from the label's 11.1w/H

    Note Mod B has a battery that on paper is 50% bigger, but only gives you 2% more button 'on' time. At 50w, Mod A will give you 5:45 of button on time, Mod B will give you 5:53 of button on time @ 50W. 8 seconds more, or a puff or two. That's it. You'll actually get more time than this because you don't run your mod constantly for 5 minutes, but chain-vaping will get closer to this time than taking a puff every couple minutes. The longer between puffs, the more recovery time the battery has which is great news for lower C rate batteries. Keep that in mind as well.

    Mod B loses more power through heat and cell inefficiency, and that battery will have a much shortened service life compared to Mod A. You might only get 300-400 cycles from Mod B, which means a new battery in a year, whereas Mod A is run less hard, isn't giving up much in actual 'button push time' and might get through 700-1000 cycles, so will last 2-3 years if you charge it once a day. Mod B being run so hard might also prematurely fail, and the chances of this are higher because it's being pushed so hard. 'Might' as in 1/1000 chance, maybe. And it might not be a 'stops working', it might be a 'Galaxy Note' type failure...

    I don't know much about these lithium batteries as I do about Nicad and NiMH, but that c rate thing is a largely lithium battery term because they do have real limits to them, and going beyond them hurts the batteries. Lithium batteries are super popular now because they pack a lot of energy into a relatively lightweight package, and give a reasonable, usable amount of power output in the bargain. Use them well and appropriately and they're great. Push them too hard and they don't work too well. Simply put, if you're pulling a lot of watts on your mod, use a battery made to give up that power (look for a higher C rate). If you want a modest number of watts and more button time, look for an appropriate and more modest c rating with more capacity (maH).

    Once you get your head around the relationship between capacity, watt/H and c rate, these batteries don't hold many secrets from you.

    And also know this is simplified and there's even more to it that I've written and my numbers are not to be taken as truth, only examples of how these things work.

    Also make sure you buy good, genuine and reliable batteries because if it's a knock off or cheapo junk, none of the above applies.

    Stu.
    Thanks for the very detailed information on battery ratings.
    So based on this, regardless of whether its a single or dual coil build, as long as the resistance is the same, the amp draw and wattage should be the same, therefore battery drain will be the same?

  6. #6
    AVF Regular
    Join Date
    Oct 2016
    Location
    Backwater Japan.
    Posts
    660
    If the only variable in the equation is the coil and it's resistance, and that's the same, then yes the drain will be the same.

    A full on engineer type could argue the drain will be ever so slightly different, but practically, no change.

    Ohms law is V(olts)= I(current)xR(resistance), and as these things are purely resistive loads, this is all you need to work out all aspects of what's going on.

    The most basic example you could use is a single cell and a 0.5ohm coil, how much current flow?

    3.7v/0.5 = 7.4A.

    To find the watts of power, V x I, 3.7 x 7.4 = 27.3w.

    Any changes you deliberately make to any of these numbers by whatever method you have available will change the other numbers according to ohms law.

    So a single 0.5 ohm coil is no different, electrically speaking, than 500 coils with a total resistance of 0.5ohms. So long as you stick to measuring your resistance across a completed and ready to use coil or set of coils, you've got all you need to know.

    (Parallel and series resistance is a can of worms you don't need to open, so long as you only measure coil packs ready to use that are physically identical or close to it. Using a pair of coils that are significantly different in overall length will give you unexpected results, so avoid it if possible.)

    Looking at my regulated mod now, 0.4ohm coil, set for 40w. What voltage does the screen tell me? 4.00v. These types of mod boxes are able to change voltage to suit a particular wattage output. They can't change the resistance, but they can step up the voltage which also increases the current flow, increasing the power output to the coil.

    You can go down this rabbit hole and argue for an against all manner of things that will affect battery life, but simply put if you use more power the battery is going to go flat faster but the relationship of power to battery life is not linear. Higher power burns up battery faster.

    Stu.

  7. #7
    AVF Regular
    Join Date
    Jun 2016
    Location
    South Australia
    Posts
    701
    Thank you Schtoo for taking the time to explain all this to me.
    Much appreciated.

  8. #8
    Super Moderator
    Join Date
    Jan 2012
    Location
    Whyalla, SA
    Posts
    13,095
    Quote Originally Posted by Schtoo View Post
    If the only variable in the equation is the coil and it's resistance, and that's the same, then yes the drain will be the same ...
    Not quite, the dual coils will take longer to get up to vaporising temperature (because there is more metal to heat) and you'll use battery life to do that.
    Ignore the Super-moderator tag in my profile, I have resigned from that position but admin have not updated my profile as yet

  9. #9
    AVF Regular
    Join Date
    Jun 2016
    Location
    South Australia
    Posts
    701
    Quote Originally Posted by gtadmin View Post
    Not quite, the dual coils will take longer to get up to vaporising temperature (because there is more metal to heat) and you'll use battery life to do that.
    So with all factors equal... (e.g. mod inefficiencies, battery inefficiencies, resistance etc) except one being a dual coil another being a single...
    A dual coil will drain a battery quicker than a single coil?

  10. #10
    Super Moderator
    Join Date
    Jan 2012
    Location
    Whyalla, SA
    Posts
    13,095
    Yes. I don't know by how much however, as I don't run dual coils or 0.3 ohm coils. It may be minimal though, as once the coil/s has been heated, it takes less energy to reheat.
    Ignore the Super-moderator tag in my profile, I have resigned from that position but admin have not updated my profile as yet

 

 
Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Powered by vBulletin® Version 4.2.4
Copyright © 2019 vBulletin Solutions, Inc. All rights reserved.
Search Engine Friendly URLs by vBSEO 3.6.0
All times are GMT +11. The time now is 12:50 AM.